101
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Attarpour A, Ward J, Chen JJ. Vascular origins of low-frequency oscillations in the cerebrospinal fluid signal in resting-state fMRI: Interpretation using photoplethysmography. Hum Brain Mapp 2021; 42:2606-2622. [PMID: 33638224 PMCID: PMC8090775 DOI: 10.1002/hbm.25392] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/09/2021] [Accepted: 02/16/2021] [Indexed: 12/12/2022] Open
Abstract
In vivo mapping of cerebrovascular oscillations in the 0.05–0.15 Hz remains difficult. Oscillations in the cerebrospinal fluid (CSF) represent a possible avenue for noninvasively tracking these oscillations using resting‐state functional MRI (rs‐fMRI), and have been used to correct for vascular oscillations in rs‐fMRI functional connectivity. However, the relationship between low‐frequency CSF and vascular oscillations remains unclear. In this study, we investigate this relationship using fast simultaneous rs‐fMRI and photoplethysmogram (PPG), examining the 0.1 Hz PPG signal, heart‐rate variability (HRV), pulse‐intensity ratio (PIR), and the second derivative of the PPG (SDPPG). The main findings of this study are: (a) signals in different CSF regions are not equivalent in their associations with vascular and tissue rs‐fMRI signals; (b) the PPG signal is maximally coherent with the arterial and CSF signals at the cardiac frequency, but coherent with brain tissue at ~0.2 Hz; (c) PIR is maximally coherent with the CSF signal near 0.03 Hz; and (d) PPG‐related vascular oscillations only contribute to ~15% of the CSF (and arterial) signal in rs‐fMRI. These findings caution against averaging all CSF regions when extracting physiological nuisance regressors in rs‐fMRI applications, and indicate the drivers of the CSF signal are more than simply cardiac. Our study is an initial attempt at the refinement and standardization of how the CSF signal in rs‐fMRI can be used and interpreted. It also paves the way for using rs‐fMRI in the CSF as a potential tool for tracking cerebrovascular health through, for instance, the potential relationship between PIR and the CSF signal.
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Affiliation(s)
- Ahmadreza Attarpour
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - James Ward
- Rotman Research Institute, Baycrest Health Sciences, Toronto, Ontario, Canada
| | - J Jean Chen
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Rotman Research Institute, Baycrest Health Sciences, Toronto, Ontario, Canada
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102
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Yankova G, Bogomyakova O, Tulupov A. The glymphatic system and meningeal lymphatics of the brain: new understanding of brain clearance. Rev Neurosci 2021; 32:693-705. [PMID: 33618444 DOI: 10.1515/revneuro-2020-0106] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 01/31/2021] [Indexed: 12/25/2022]
Abstract
The glymphatic system and meningeal lymphatics have recently been characterized. Glymphatic system is a glia-dependent system of perivascular channels, and it plays an important role in the removal of interstitial metabolic waste products. The meningeal lymphatics may be a key drainage route for cerebrospinal fluid into the peripheral blood, may contribute to inflammatory reaction and central nervous system (CNS) immune surveillance. Breakdowns and dysfunction of the glymphatic system and meningeal lymphatics play a crucial role in age-related brain changes, the pathogenesis of neurovascular and neurodegenerative diseases, as well as in brain injuries and tumors. This review discusses the relationship recently characterized meningeal lymphatic vessels with the glymphatic system, which provides perfusion of the CNS with cerebrospinal and interstitial fluids. The review also presents the results of human studies concerning both the presence of meningeal lymphatics and the glymphatic system. A new understanding of how aging, medications, sleep and wake cycles, genetic predisposition, and even body posture affect the brain drainage system has not only changed the idea of brain fluid circulation but has also contributed to an understanding of the pathology and mechanisms of neurodegenerative diseases.
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Affiliation(s)
- Galina Yankova
- Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk630090, Russia.,Novosibirsk State University, Novosibirsk630090,Russia
| | - Olga Bogomyakova
- International Tomography Center, Siberian Branch, Russian Academy of Sciences, Novosibirsk630090, Russia
| | - Andrey Tulupov
- Novosibirsk State University, Novosibirsk630090,Russia.,International Tomography Center, Siberian Branch, Russian Academy of Sciences, Novosibirsk630090, Russia.,Meshalkin National Medical Research Center, Ministry of Health of Russian Federation, Novosibirsk 630055, Russia
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103
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Wang Y, van Gelderen P, de Zwart JA, Campbell-Washburn AE, Duyn JH. FMRI based on transition-band balanced SSFP in comparison with EPI on a high-performance 0.55 T scanner. Magn Reson Med 2021; 85:3196-3210. [PMID: 33480108 DOI: 10.1002/mrm.28657] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/23/2020] [Accepted: 12/05/2020] [Indexed: 02/03/2023]
Abstract
PURPOSE Low-field (<1 tesla) MRI scanners allow more widespread diagnostic use for a range of cardiac, musculoskeletal, and neurological applications. However, the feasibility of performing robust fMRI at low field has yet to be fully demonstrated. To address this gap, we investigated task-based fMRI using a highly sensitive transition-band balanced steady-state free precession approach and standard EPI on a 0.55 tesla scanner equipped with modern high-performance gradient coils and a receive array. METHODS TR and flip-angle of transition-band steady-state free precession were optimized for 0.55 tesla by simulations. Static shimming was employed to compensate for concomitant field effects. Visual task-based fMRI data were acquired from 8 healthy volunteers. For comparison, standard EPI data were also acquired with TE = T 2 ∗ . Retrospective image-based correction for physiological effects (RETROICOR) was used to quantify physiological noise effects. RESULTS Activation was robustly detected using both methods in a 4-min scan time. Transition-band steady-state free precession was found to be sensitive to interference from subtle spatial and temporal (field drift, respiration) variations in the magnetic field, counteracting potential advantages of the reduced magnetic susceptibility effects compared to its utilization at high field. These adverse effects could be partially remedied with static shimming and postprocessing approaches. Standard EPI proved more robust against the sources of interference. CONCLUSION BOLD contrast is sufficiently large at 0.55 tesla for robust detection of brain activation and may be employed to broaden the spectrum of applications of low-field MRI. Standard EPI outperforms transition-band steady-state free precession in terms of signal stability.
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Affiliation(s)
- Yicun Wang
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Peter van Gelderen
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Jacco A de Zwart
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jeff H Duyn
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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104
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Proulx ST. Cerebrospinal fluid outflow: a review of the historical and contemporary evidence for arachnoid villi, perineural routes, and dural lymphatics. Cell Mol Life Sci 2021; 78:2429-2457. [PMID: 33427948 PMCID: PMC8004496 DOI: 10.1007/s00018-020-03706-5] [Citation(s) in RCA: 158] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/23/2020] [Accepted: 11/06/2020] [Indexed: 12/19/2022]
Abstract
Cerebrospinal fluid (CSF) is produced by the choroid plexuses within the ventricles of the brain and circulates through the subarachnoid space of the skull and spinal column to provide buoyancy to and maintain fluid homeostasis of the brain and spinal cord. The question of how CSF drains from the subarachnoid space has long puzzled scientists and clinicians. For many decades, it was believed that arachnoid villi or granulations, outcroppings of arachnoid tissue that project into the dural venous sinuses, served as the major outflow route. However, this concept has been increasingly challenged in recent years, as physiological and imaging evidence from several species has accumulated showing that tracers injected into the CSF can instead be found within lymphatic vessels draining from the cranium and spine. With the recent high-profile rediscovery of meningeal lymphatic vessels located in the dura mater, another debate has emerged regarding the exact anatomical pathway(s) for CSF to reach the lymphatic system, with one side favoring direct efflux to the dural lymphatic vessels within the skull and spinal column and another side advocating for pathways along exiting cranial and spinal nerves. In this review, a summary of the historical and contemporary evidence for the different outflow pathways will be presented, allowing the reader to gain further perspective on the recent advances in the field. An improved understanding of this fundamental physiological process may lead to novel therapeutic approaches for a wide range of neurological conditions, including hydrocephalus, neurodegeneration and multiple sclerosis.
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Affiliation(s)
- Steven T Proulx
- Theodor Kocher Institute, University of Bern, Bern, Switzerland.
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105
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Young BA, Adams J, Beary JM, Mardal KA, Schneider R, Kondrashova T. The myodural bridge of the American alligator ( Alligator mississippiensis) alters CSF flow. J Exp Biol 2020; 223:jeb230896. [PMID: 33077640 DOI: 10.1242/jeb.230896] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/11/2020] [Indexed: 12/19/2022]
Abstract
Disorders of the volume, pressure or circulation of the cerebrospinal fluid (CSF) lead to disease states in both newborns and adults; despite this significance, there is uncertainty regarding the basic mechanics of the CSF. The suboccipital muscles connect to the dura surrounding the spinal cord, forming a complex termed the 'myodural bridge'. This study tests the hypothesis that the myodural bridge functions to alter the CSF circulation. The suboccipital muscles of American alligators were surgically exposed and electrically stimulated simultaneously with direct recordings of CSF pressure and flow. Contraction of the suboccipital muscles significantly changed both CSF flow and pressure. By demonstrating another influence on CSF circulation and pulsatility, the present study increases our understanding of the mechanics underlying the movement of the CSF.
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Affiliation(s)
- Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | - James Adams
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | - Jonathan M Beary
- Department of Behavioral Neuroscience, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | | | - Robert Schneider
- Department of Family Medicine, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
| | - Tatyana Kondrashova
- Department of Family Medicine, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO 63501, USA
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106
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Khasawneh AH, Alexandra PC, Zajciw PA, Harris CA. A preliminary exploration of acute intracranial pressure-cerebrospinal fluid production relationships in experimental hydrocephalus. Brain Circ 2020; 6:200-207. [PMID: 33210046 PMCID: PMC7646388 DOI: 10.4103/bc.bc_42_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 09/10/2020] [Accepted: 09/13/2020] [Indexed: 11/04/2022] Open
Abstract
CONTEXT By occluding the fourth ventricle simultaneously obtaining telemetric data on intracranial pressure (ICP) and cerebrospinal fluid (CSF) production, the authors of this study investigate a variety of physiologic parameters in cases of experimental hydrocephalus. AIMS The aim of this study is to provide a new context on the disrupted homeostasis in hydrocephalus and guide toward improved treatment based on multiple physiological parameters. MATERIALS AND METHODS Hydrocephalus was induced in ten 21-day-old Sprague-Dawley rats by blocking the flow of CSF to the fourth ventricle with kaolin. Ten days post induction, when physical signs of ventriculomegaly reached Evan's ratio (ER) of ≥0.46, CSF flow and ICP were measured while manipulating body position (0°, 45°, 90°) and heart rate. RESULTS In hydrocephalic animals (ER ≥0.46), we found a near-steady average acute ICP (13.638 ± 2.331) compared to age-matched controls (ER <0.30) (13.068 ± 8.781), whose ICP fluctuated with the position. Hydrocephalic and controls exhibited an insignificant degree of parabolic shifts in CSF production when body position was changed from prone to 90° and again when moved back to the prone position, a trend more noteworthy in controls (P = 0.1322 and 0.2772). A Pearson's Correlation found CSF production and ICP to be correlated at baseline 0° posture (P = 0.05) in the control group, but not the hydrocephalic group. Weight appeared to play a role when animals were held at 90°. No significant changes in ICP or CSF flow patterns were observed when the heart rate was increased within either group. CONCLUSIONS These preliminary findings suggest that our standard assumptions of posture-dependent changes in ICP created using data from physiologic data may be inaccurate in the hydrocephalic patient, and thus describe a need to further explore these relationships.
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Affiliation(s)
- Ahmad H Khasawneh
- Department of Chemical Engineering, Wayne State University, Detroit, Michigan, USA
| | - Petroj C Alexandra
- Department of Chemical Engineering, Wayne State University, Detroit, Michigan, USA
| | - Paul A Zajciw
- Department of Chemical Engineering, Wayne State University, Detroit, Michigan, USA
| | - Carolyn A Harris
- Department of Chemical Engineering, Wayne State University, Detroit, Michigan, USA.,Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, USA.,Department of Neurosurgery, Wayne State University, Detroit, Michigan, USA
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107
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Hennig J, Kiviniemi V, Riemenschneider B, Barghoorn A, Akin B, Wang F, LeVan P. 15 Years MR-encephalography. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2020; 34:85-108. [PMID: 33079327 PMCID: PMC7910380 DOI: 10.1007/s10334-020-00891-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/02/2020] [Accepted: 09/29/2020] [Indexed: 02/07/2023]
Abstract
Objective This review article gives an account of the development of the MR-encephalography (MREG) method, which started as a mere ‘Gedankenexperiment’ in 2005 and gradually developed into a method for ultrafast measurement of physiological activities in the brain. After going through different approaches covering k-space with radial, rosette, and concentric shell trajectories we have settled on a stack-of-spiral trajectory, which allows full brain coverage with (nominal) 3 mm isotropic resolution in 100 ms. The very high acceleration factor is facilitated by the near-isotropic k-space coverage, which allows high acceleration in all three spatial dimensions. Methods The methodological section covers the basic sequence design as well as recent advances in image reconstruction including the targeted reconstruction, which allows real-time feedback applications, and—most recently—the time-domain principal component reconstruction (tPCR), which applies a principal component analysis of the acquired time domain data as a sparsifying transformation to improve reconstruction speed as well as quality. Applications Although the BOLD-response is rather slow, the high speed acquisition of MREG allows separation of BOLD-effects from cardiac and breathing related pulsatility. The increased sensitivity enables direct detection of the dynamic variability of resting state networks as well as localization of single interictal events in epilepsy patients. A separate and highly intriguing application is aimed at the investigation of the glymphatic system by assessment of the spatiotemporal patterns of cardiac and breathing related pulsatility. Discussion MREG has been developed to push the speed limits of fMRI. Compared to multiband-EPI this allows considerably faster acquisition at the cost of reduced image quality and spatial resolution.
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Affiliation(s)
- Juergen Hennig
- Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center University of Freiburg, University of Freiburg, Freiburg, Germany. .,Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Vesa Kiviniemi
- Oulu Functional NeuroImaging Group, Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
| | - Bruno Riemenschneider
- Department of Radiology, Center for Biomedical Imaging, New York University Grossman School of Medicine, New York, NY, USA
| | - Antonia Barghoorn
- Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center University of Freiburg, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Burak Akin
- Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center University of Freiburg, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Fei Wang
- Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center University of Freiburg, University of Freiburg, Freiburg, Germany.,Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Pierre LeVan
- Departments of Radiology and Paediatrics, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
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108
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Bryniarski MA, Ren T, Rizvi AR, Snyder AM, Morris ME. Targeting the Choroid Plexuses for Protein Drug Delivery. Pharmaceutics 2020; 12:pharmaceutics12100963. [PMID: 33066423 PMCID: PMC7602164 DOI: 10.3390/pharmaceutics12100963] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 10/05/2020] [Accepted: 10/10/2020] [Indexed: 12/15/2022] Open
Abstract
Delivery of therapeutic agents to the central nervous system is challenged by the barriers in place to regulate brain homeostasis. This is especially true for protein therapeutics. Targeting the barrier formed by the choroid plexuses at the interfaces of the systemic circulation and ventricular system may be a surrogate brain delivery strategy to circumvent the blood-brain barrier. Heterogenous cell populations located at the choroid plexuses provide diverse functions in regulating the exchange of material within the ventricular space. Receptor-mediated transcytosis may be a promising mechanism to deliver protein therapeutics across the tight junctions formed by choroid plexus epithelial cells. However, cerebrospinal fluid flow and other barriers formed by ependymal cells and perivascular spaces should also be considered for evaluation of protein therapeutic disposition. Various preclinical methods have been applied to delineate protein transport across the choroid plexuses, including imaging strategies, ventriculocisternal perfusions, and primary choroid plexus epithelial cell models. When used in combination with simultaneous measures of cerebrospinal fluid dynamics, they can yield important insight into pharmacokinetic properties within the brain. This review aims to provide an overview of the choroid plexuses and ventricular system to address their function as a barrier to pharmaceutical interventions and relevance for central nervous system drug delivery of protein therapeutics. Protein therapeutics targeting the ventricular system may provide new approaches in treating central nervous system diseases.
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109
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Benveniste H, Elkin R, Heerdt PM, Koundal S, Xue Y, Lee H, Wardlaw J, Tannenbaum A. The glymphatic system and its role in cerebral homeostasis. J Appl Physiol (1985) 2020; 129:1330-1340. [PMID: 33002383 DOI: 10.1152/japplphysiol.00852.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The brain's high bioenergetic state is paralleled by high metabolic waste production. Authentic lymphatic vasculature is lacking in brain parenchyma. Cerebrospinal fluid (CSF) flow has long been thought to facilitate central nervous system detoxification in place of lymphatics, but the exact processes involved in toxic waste clearance from the brain remain incompletely understood. Over the past 8 yr, novel data in animals and humans have begun to shed new light on these processes in the form of the "glymphatic system," a brain-wide perivascular transit passageway dedicated to CSF transport and interstitial fluid exchange that facilitates metabolic waste drainage from the brain. Here we will discuss glymphatic system anatomy and methods to visualize and quantify glymphatic system (GS) transport in the brain and also discuss physiological drivers of its function in normal brain and in neurodegeneration.
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Affiliation(s)
- Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
| | - Rena Elkin
- Departments of Computer Science and Applied Mathematics & Statistics, Stony Brook University, Stony Brook, New York
| | - Paul M Heerdt
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
| | - Sunil Koundal
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
| | - Yuechuan Xue
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
| | - Hedok Lee
- Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
| | - Joanna Wardlaw
- Brain Research Imaging Centre, Centre for Clinical Brain Sciences, Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
| | - Allen Tannenbaum
- Departments of Computer Science and Applied Mathematics & Statistics, Stony Brook University, Stony Brook, New York
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110
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Abstract
Adaption to changes of external environment or internal health, the body-mind connection, or autonomic nervous system must be flexible and healthy. Population health studies with wearable technology and remote monitoring will lead to paradigm shifts in how to approach the physiology of emotion. Heart rate variability as a whole health biomarker could emerge as a foundation for a process beginning with objective habits and skills of real-time modulation with focused breathing for healthier decision making and autonomic health trajectory change. Physical medicine and rehabilitation is uniquely poised to refine an autonomic rehabilitation process in an integrative manner to help individuals adapt.
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Affiliation(s)
- Raouf S Gharbo
- Department of Physical Medicine and Rehabilitation, Virginia Commonwealth University, 109 Elizabeth Meriwether, Williamsburg, VA 23185, USA.
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111
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Longatti P, Fiorindi A, Peruzzo P, Basaldella L, Susin FM. Form follows function: estimation of CSF flow in the third ventricle-aqueduct-fourth ventricle complex modeled as a diffuser/nozzle pump. J Neurosurg 2020; 133:894-901. [PMID: 31419793 DOI: 10.3171/2019.5.jns19276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 05/10/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE In the last 20 years, researchers have debated cerebrospinal fluid (CSF) dynamics theories, commonly based on the classic bulk flow perspective. New hypotheses do not consider a possible hydraulic impact of the ventricular morphology. The present study investigates, by means of a mathematical model, the eventual role played by the geometric shape of the "third ventricle-aqueduct-fourth ventricle" complex in CSF circulation under the assumption that the complex behaves like a diffuser/nozzle (DN) pump. METHODS DN pumps are quite recent devices introduced as valveless micropumps in various industrial applications given their property of driving net flow when subjected to rhythmic pulsations. A novel peculiar DN pump configuration was adopted in this study to mimic the ventricular complex, with two reservoirs (the ventricles) and one tube provided with a conical reach (the aqueduct-proximal fourth ventricle). The flow was modeled according to the classic equations of laminar flow, and the external rhythmic pulsations forcing the system were reproduced as a pulsatile pressure gradient between the chambers. Several physiological scenarios were implemented with the integration of data acquired by MRI in 10 patients with no known pathology of CSF dynamics, and a quantitative analysis of the effect of geometric and hydraulic parameters (diverging angle, sizes, frequency of pulsations) on the CSF net flow was performed. RESULTS The results showed a craniocaudal net flow in all the given values, consistent with the findings of cine MRI studies. Moreover, the net flow estimated for the analyzed cohort of patients ranged from 0.221 to 0.505 ml/min, remarkably close to the values found on phase contrast cine MRI in healthy subjects. Sensitivity analysis underlines the pivotal role of the DN configuration, as well as of the frequency of forcing pressure, which promotes a relevant net flow considering both the heart and respiration rate. CONCLUSIONS This work suggests that the geometry of the third ventricle-aqueduct-fourth ventricle complex, which resembles a diverter, appears to be functional in the generation of a net craniocaudal flow and potentially has an impact on CSF dynamics. These conclusions can be drawn by observing the analogies between the shape of the ventricles and the geometry of DN pumps and by recognizing the basis of the mathematical model of the simplified third ventricle-aqueduct-fourth ventricle complex proposed.
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Affiliation(s)
| | | | - Paolo Peruzzo
- 2Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering, University of Padova, Italy
| | - Luca Basaldella
- 1Neurosurgical Unit, Treviso Hospital, University of Padova; and
| | - Francesca Maria Susin
- 2Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering, University of Padova, Italy
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112
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Ng Kee Kwong KC, Mehta AR, Nedergaard M, Chandran S. Defining novel functions for cerebrospinal fluid in ALS pathophysiology. Acta Neuropathol Commun 2020; 8:140. [PMID: 32819425 PMCID: PMC7439665 DOI: 10.1186/s40478-020-01018-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 08/10/2020] [Indexed: 12/11/2022] Open
Abstract
Despite the considerable progress made towards understanding ALS pathophysiology, several key features of ALS remain unexplained, from its aetiology to its epidemiological aspects. The glymphatic system, which has recently been recognised as a major clearance pathway for the brain, has received considerable attention in several neurological conditions, particularly Alzheimer's disease. Its significance in ALS has, however, been little addressed. This perspective article therefore aims to assess the possibility of CSF contribution in ALS by considering various lines of evidence, including the abnormal composition of ALS-CSF, its toxicity and the evidence for impaired CSF dynamics in ALS patients. We also describe a potential role for CSF circulation in determining disease spread as well as the importance of CSF dynamics in ALS neurotherapeutics. We propose that a CSF model could potentially offer additional avenues to explore currently unexplained features of ALS, ultimately leading to new treatment options for people with ALS.
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Affiliation(s)
- Koy Chong Ng Kee Kwong
- UK Dementia Research Institute at University of Edinburgh, Edinburgh, UK
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh bioQuarter, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
- Euan MacDonald Centre for MND Research, University of Edinburgh, Edinburgh, UK
| | - Arpan R Mehta
- UK Dementia Research Institute at University of Edinburgh, Edinburgh, UK
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh bioQuarter, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
- Euan MacDonald Centre for MND Research, University of Edinburgh, Edinburgh, UK
- Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
| | - Siddharthan Chandran
- UK Dementia Research Institute at University of Edinburgh, Edinburgh, UK.
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh bioQuarter, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
- Euan MacDonald Centre for MND Research, University of Edinburgh, Edinburgh, UK.
- Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh, UK.
- Centre for Brain Development and Repair, inStem, Bangalore, India.
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113
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Kedarasetti RT, Turner KL, Echagarruga C, Gluckman BJ, Drew PJ, Costanzo F. Functional hyperemia drives fluid exchange in the paravascular space. Fluids Barriers CNS 2020; 17:52. [PMID: 32819402 PMCID: PMC7441569 DOI: 10.1186/s12987-020-00214-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 08/09/2020] [Indexed: 12/20/2022] Open
Abstract
The brain lacks a conventional lymphatic system to remove metabolic waste. It has been proposed that directional fluid movement through the arteriolar paravascular space (PVS) promotes metabolite clearance. We performed simulations to examine if arteriolar pulsations and dilations can drive directional CSF flow in the PVS and found that arteriolar wall movements do not drive directional CSF flow. We propose an alternative method of metabolite clearance from the PVS, namely fluid exchange between the PVS and the subarachnoid space (SAS). In simulations with compliant brain tissue, arteriolar pulsations did not drive appreciable fluid exchange between the PVS and the SAS. However, when the arteriole dilated, as seen during functional hyperemia, there was a marked exchange of fluid. Simulations suggest that functional hyperemia may serve to increase metabolite clearance from the PVS. We measured blood vessels and brain tissue displacement simultaneously in awake, head-fixed mice using two-photon microscopy. These measurements showed that brain deforms in response to pressure changes in PVS, consistent with our simulations. Our results show that the deformability of the brain tissue needs to be accounted for when studying fluid flow and metabolite transport.
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Affiliation(s)
- Ravi Teja Kedarasetti
- Center for Neural Engineering, The Pennsylvania State University, University Park, PA, USA
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
| | - Kevin L Turner
- Center for Neural Engineering, The Pennsylvania State University, University Park, PA, USA
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Christina Echagarruga
- Center for Neural Engineering, The Pennsylvania State University, University Park, PA, USA
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Bruce J Gluckman
- Center for Neural Engineering, The Pennsylvania State University, University Park, PA, USA
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA
- Department of Neurosurgery, The Pennsylvania State University, University Park, PA, USA
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Patrick J Drew
- Center for Neural Engineering, The Pennsylvania State University, University Park, PA, USA.
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
- Department of Neurosurgery, The Pennsylvania State University, University Park, PA, USA.
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA.
| | - Francesco Costanzo
- Center for Neural Engineering, The Pennsylvania State University, University Park, PA, USA.
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA.
- Department of Mathematics, The Pennsylvania State University, University Park, PA, USA.
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114
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Daems M, Peacock HM, Jones EAV. Fluid flow as a driver of embryonic morphogenesis. Development 2020; 147:147/15/dev185579. [PMID: 32769200 DOI: 10.1242/dev.185579] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fluid flow is a powerful morphogenic force during embryonic development. The physical forces created by flowing fluids can either create morphogen gradients or be translated by mechanosensitive cells into biological changes in gene expression. In this Primer, we describe how fluid flow is created in different systems and highlight the important mechanosensitive signalling pathways involved for sensing and transducing flow during embryogenesis. Specifically, we describe how fluid flow helps establish left-right asymmetry in the early embryo and discuss the role of flow of blood, lymph and cerebrospinal fluid in sculpting the embryonic cardiovascular and nervous system.
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Affiliation(s)
- Margo Daems
- Department of Cardiovascular Sciences, Centre for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
| | - Hanna M Peacock
- Department of Cardiovascular Sciences, Centre for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
| | - Elizabeth A V Jones
- Department of Cardiovascular Sciences, Centre for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
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115
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Sonnabend K, Brinker G, Maintz D, Bunck AC, Weiss K. Cerebrospinal fluid pulse wave velocity measurements: In vitro and in vivo evaluation of a novel multiband cine phase-contrast MRI sequence. Magn Reson Med 2020; 85:197-208. [PMID: 32783240 DOI: 10.1002/mrm.28430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/27/2020] [Accepted: 06/23/2020] [Indexed: 12/28/2022]
Abstract
PURPOSE Intracranial and intraspinal compliance are parameters of interest in the diagnosis and prediction of treatment outcome in patients with normal pressure hydrocephalus and other forms of communicating hydrocephalus. A noninvasive method to estimate the spinal cerebrospinal fluid (CSF) pulse wave velocity (PWV) as a measure of compliance was developed using a multiband cine phase-contrast MRI sequence and a foot-to-foot algorithm. METHODS We used computational simulations to estimate the accuracy of the MRI acquisition and transit-time algorithm. In vitro measurements were performed to investigate the reproducibility and accuracy of the measurements under controlled conditions. In vivo measurements in 20 healthy subjects and 2 patients with normal pressure hydrocephalus were acquired to show the technical feasibility in a clinical setting. RESULTS Simulations showed a mean deviation of the calculated CSF PWV of 3.41% ± 2.68%. In vitro results were in line with theory, showing a square-root relation between PWV and transmural pressure and a good reproducibility with SDs of repeated measurements below 5%. Mean CSF PWV over all healthy subjects was 5.83 ± 3.36 m/s. The CSF PWV measurements in the patients with normal pressure hydrocephalus were distinctly higher before CSF shunt surgery (33.80 ± 6.75 m/s and 31.31 ± 7.82 m/s), with a decrease 5 days after CSF shunt surgery (15.69 ± 3.37 m/s). CONCLUSION This study evaluates the feasibility of CSF PWV measurements using a multiband cine phase-contrast MRI sequence. In vitro and in vivo measurements showed that this method is a potential tool for the noninvasive estimation of intraspinal compliance.
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Affiliation(s)
- Kristina Sonnabend
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Gerrit Brinker
- Department of General Neurosurgery, Center for Neurosurgery, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - David Maintz
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Alexander C Bunck
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Kilian Weiss
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.,Philips GmbH, Hamburg, Germany
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116
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Jaeger E, Sonnabend K, Schaarschmidt F, Maintz D, Weiss K, Bunck AC. Compressed-sensing accelerated 4D flow MRI of cerebrospinal fluid dynamics. Fluids Barriers CNS 2020; 17:43. [PMID: 32677977 PMCID: PMC7364783 DOI: 10.1186/s12987-020-00206-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/06/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND 4D flow magnetic resonance imaging (MRI) of CSF can make an important contribution to the understanding of hydrodynamic changes in various neurological diseases but remains limited in clinical application due to long acquisition times. The aim of this study was to evaluate the accuracy of compressed SENSE accelerated MRI measurements of the spinal CSF flow. METHODS In 20 healthy subjects 4D flow MRI of the CSF in the cervical spine was acquired using compressed sensitivity encoding [CSE, a combination of compressed sensing and parallel imaging (SENSE) provided by the manufacturer] with acceleration factors between 4 and 10. A conventional scan using SENSE was used as reference. Extracted parameters were peak velocity, absolute net flow, forward flow and backward flow. Bland-Altman analysis was performed to determine the scan-rescan reproducibility and the agreement between SENSE and compressed SENSE. Additionally, a time accumulated flow error was calculated. In one additional subject flow of the spinal canal at the level of the entire spinal cord was assessed. RESULTS Averaged acquisition times were 10:21 min (SENSE), 9:31 min (CSE4), 6:25 min (CSE6), 4:53 min (CSE8) and 3:51 min (CSE10). Acquisition of the CSF flow surrounding the entire spinal cord took 14:40 min. Bland-Altman analysis showed good agreement for peak velocity, but slight overestimations for absolute net flow, forward flow and backward flow (< 1 ml/min) in CSE4-8. Results of the accumulated flow error were similar for CSE4 to CSE8. CONCLUSION A quantitative analysis of acceleration factors CSE4-10 showed that CSE with an acceleration factor up to 6 is feasible. This allows a scan time reduction of 40% and enables the acquisition and analysis of the CSF flow dynamics surrounding the entire spinal cord within a clinically acceptable scan time.
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Affiliation(s)
- Elena Jaeger
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Street 62, 50937, Cologne, Germany
| | - Kristina Sonnabend
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Street 62, 50937, Cologne, Germany.
| | - Frank Schaarschmidt
- Institute of Cell Biology and Biophysics, Biostatistics Department, Leibniz University Hannover, Hannover, Germany
| | - David Maintz
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Street 62, 50937, Cologne, Germany
| | - Kilian Weiss
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Street 62, 50937, Cologne, Germany.,Philips GmbH, Hamburg, Germany
| | - Alexander C Bunck
- Department of Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Street 62, 50937, Cologne, Germany
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117
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Kananen J, Helakari H, Korhonen V, Huotari N, Järvelä M, Raitamaa L, Raatikainen V, Rajna Z, Tuovinen T, Nedergaard M, Jacobs J, LeVan P, Ansakorpi H, Kiviniemi V. Respiratory-related brain pulsations are increased in epilepsy-a two-centre functional MRI study. Brain Commun 2020; 2:fcaa076. [PMID: 32954328 PMCID: PMC7472909 DOI: 10.1093/braincomms/fcaa076] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/29/2020] [Accepted: 05/05/2020] [Indexed: 01/03/2023] Open
Abstract
Resting-state functional MRI has shown potential for detecting changes in cerebral blood oxygen level-dependent signal in patients with epilepsy, even in the absence of epileptiform activity. Furthermore, it has been suggested that coefficient of variation mapping of fast functional MRI signal may provide a powerful tool for the identification of intrinsic brain pulsations in neurological diseases such as dementia, stroke and epilepsy. In this study, we used fast functional MRI sequence (magnetic resonance encephalography) to acquire ten whole-brain images per second. We used the functional MRI data to compare physiological brain pulsations between healthy controls (n = 102) and patients with epilepsy (n = 33) and furthermore to drug-naive seizure patients (n = 9). Analyses were performed by calculating coefficient of variation and spectral power in full band and filtered sub-bands. Brain pulsations in the respiratory-related frequency sub-band (0.11-0.51 Hz) were significantly (P < 0.05) increased in patients with epilepsy, with an increase in both signal variance and power. At the individual level, over 80% of medicated and drug-naive seizure patients exhibited areas of abnormal brain signal power that correlated well with the known clinical diagnosis, while none of the controls showed signs of abnormality with the same threshold. The differences were most apparent in the basal brain structures, respiratory centres of brain stem, midbrain and temporal lobes. Notably, full-band, very low frequency (0.01-0.1 Hz) and cardiovascular (0.8-1.76 Hz) brain pulses showed no differences between groups. This study extends and confirms our previous results of abnormal fast functional MRI signal variance in epilepsy patients. Only respiratory-related brain pulsations were clearly increased with no changes in either physiological cardiorespiratory rates or head motion between the subjects. The regional alterations in brain pulsations suggest that mechanisms driving the cerebrospinal fluid homeostasis may be altered in epilepsy. Magnetic resonance encephalography has both increased sensitivity and high specificity for detecting the increased brain pulsations, particularly in times when other tools for locating epileptogenic areas remain inconclusive.
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Affiliation(s)
- Janne Kananen
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Heta Helakari
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Vesa Korhonen
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Niko Huotari
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Matti Järvelä
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Lauri Raitamaa
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Ville Raatikainen
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Zalan Rajna
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Center for Machine Vision and Signal Analysis (CMVS), University of Oulu, Oulu 90014, Finland
| | - Timo Tuovinen
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642, USA
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Julia Jacobs
- Department of Pediatric Neurology and Muscular Disease, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg 79110, Germany
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
- Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
- Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Pierre LeVan
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
- Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
- Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
- Department of Radiology, Medical Physics, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg 79110, Germany
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Hanna Ansakorpi
- Medical Research Center (MRC), Oulu 90220, Finland
- Research Unit of Neuroscience, Neurology, University of Oulu, Oulu 90220, Finland
- Department of Neurology, Oulu University Hospital, Oulu 90029, Finland
| | - Vesa Kiviniemi
- Oulu Functional NeuroImaging (OFNI), Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90029, Finland
- Medical Imaging, Physics and Technology (MIPT), Faculty of Medicine, University of Oulu, Oulu 90220, Finland
- Medical Research Center (MRC), Oulu 90220, Finland
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Chen Y, O'Shaughnessy TJ, Kamimori GH, Horner DM, Egnoto MJ, Bagchi A. Role of Interfacial Conditions on Blast Overpressure Propagation Into the Brain. Front Neurol 2020; 11:323. [PMID: 32411085 PMCID: PMC7198757 DOI: 10.3389/fneur.2020.00323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/03/2020] [Indexed: 11/13/2022] Open
Abstract
The complex interfacial condition between the human brain and the skull has been difficult to emulate in a surrogate system. Surrogate head models have typically been built using a homogeneous viscoelastic material to represent the brain, but the effect of different interfacial conditions between the brain and the skull on pressure transduction into the brain during blast has not been studied. In the present work, three interfacial conditions were generated in physical surrogate human head models. The first surrogate consisted of a gel brain separated from the skull by a layer of saline solution similar in thickness to the cerebrospinal fluid (CSF) layer in the human head: the fluid interface head model. The second surrogate head had the entire cranial cavity filled with the gel: the fixed interface head model. The third surrogate head contained a space-filling gel brain wrapped in a thin plastic film: the stick-slip interface head model. The human head surrogates were evaluated in a series of frontal blast tests to characterize the effect of skull-brain interfacial conditions on overpressure propagation into the gel brains. The fixed and the stick-slip interface head models showed nearly equal peak brain overpressures. In contrast, the fluid interface head model had much higher in-brain peak overpressures than the other two models, thus representing the largest transmission of forces into the gel brain. Given that the elevated peak overpressures occurred only in the fluid interface head model, the presence of the saline layer is likely responsible for this increase. This phenomenon is hypothesized to be attributed to the incompressibility of the saline and/or the impedance differences between the materials. The fixed interface head model showed pronounced high frequency energy content relative to the other two models, implying that the fluid and the stick-slip conditions provided better dampening. The cumulative impulse energy entering the three brain models were similar, suggesting that the interface conditions do not affect the total energy transmission over the positive phase duration of a blast event. This study shows that the fidelity of the surrogate human head models would improve with a CSF-emulating liquid layer.
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Affiliation(s)
- YungChia Chen
- Multifunctional Materials Branch, US Naval Research Laboratory, Washington, DC, United States
| | - Thomas J O'Shaughnessy
- Multifunctional Materials Branch, US Naval Research Laboratory, Washington, DC, United States
| | - Gary H Kamimori
- Blast Induced Neurotrauma, Walter Reed Army Institute of Research, Silver Springs, MD, United States
| | | | - Michael J Egnoto
- Blast Induced Neurotrauma, Walter Reed Army Institute of Research, Silver Springs, MD, United States
| | - Amit Bagchi
- Multifunctional Materials Branch, US Naval Research Laboratory, Washington, DC, United States
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119
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Measurement of Tongue Tip Velocity from Real-Time MRI and Phase-Contrast Cine-MRI in Consonant Production. J Imaging 2020; 6:jimaging6050031. [PMID: 34460733 PMCID: PMC8321019 DOI: 10.3390/jimaging6050031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 04/30/2020] [Accepted: 05/06/2020] [Indexed: 11/17/2022] Open
Abstract
We evaluate velocity of the tongue tip with magnetic resonance imaging (MRI) using two independent approaches. The first one consists in acquisition with a real-time technique in the mid-sagittal plane. Tracking of the tongue tip manually and with a computer vision method allows its trajectory to be found and the velocity to be calculated as the derivative of the coordinate. We also propose to use another approach—phase contrast MRI—which enables velocities of the moving tissues to be measured directly. We recorded the sound simultaneously with the MR acquisition which enabled us to make conclusions regarding the relation between the movements and the sound. We acquired the data from two French-speaking subjects articulating /tata/. The results of both methods are in qualitative agreement and are consistent with other reviewer techniques used for evaluation of the tongue tip velocity.
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120
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Real-Time Magnetic Resonance Imaging: Radial Gradient-Echo Sequences With Nonlinear Inverse Reconstruction. Invest Radiol 2020; 54:757-766. [PMID: 31261294 DOI: 10.1097/rli.0000000000000584] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The aim of this study is to evaluate a real-time magnetic resonance imaging (MRI) method that not only promises high spatiotemporal resolution but also practical robustness in a wide range of scientific and clinical applications. MATERIALS AND METHODS The proposed method relies on highly undersampled gradient-echo sequences with radial encoding schemes. The serial image reconstruction process solves the true mathematical task that emerges as a nonlinear inverse problem with the complex image and all coil sensitivity maps as unknowns. Extensions to model-based reconstructions for quantitative parametric mapping further increase the number of unknowns, for example, by adding parameters for phase-contrast flow or T1 relaxation. In all cases, an iterative numerical solution that minimizes a respective cost function is achieved with use of the iteratively regularized Gauss-Newton method. Convergence is supported by regularization, for example, to the preceding frame, whereas temporal fidelity is ensured by downsizing the regularization strength in comparison to the data consistency term in each iterative step. Practical implementations of highly parallelized algorithms are realized on a computer with multiple graphical processing units. It is "invisibly" integrated into a commercial 3-T MRI system to allow for conventional usage and to provide online reconstruction, display, and storage of regular DICOM image series. RESULTS Depending on the application, the proposed method offers serial imaging, that is, the recording of MRI movies, with variable spatial resolution and up to 100 frames per second (fps)-corresponding to 10 milliseconds image acquisition times. For example, movements of the temporomandibular joint during opening and closing of the mouth are visualized with use of simultaneous dual-slice movies of both joints at 2 × 10 fps (50 milliseconds per frame). Cardiac function may be studied at 30 to 50 fps (33.3 to 20 milliseconds), whereas articulation processes typically require 50 fps (20 milliseconds) or orthogonal dual-slice acquisitions at 2 × 25 fps (20 milliseconds). Methodological extensions to model-based reconstructions achieve improved quantitative mapping of flow velocities and T1 relaxation times in a variety of clinical scenarios. CONCLUSIONS Real-time gradient-echo MRI with extreme radial undersampling and nonlinear inverse reconstruction allows for direct monitoring of arbitrary physiological processes and body functions. In many cases, pertinent applications offer hitherto impossible clinical studies (eg, of high-resolution swallowing dynamics) or bear the potential to replace existing MRI procedures (eg, electrocardiogram-gated cardiac examinations). As a consequence, many novel opportunities will require a change of paradigm in MRI-based radiology. At this stage, extended clinical trials are needed.
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121
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Yamada S, Ishikawa M, Ito H, Yamamoto K, Yamaguchi M, Oshima M, Nozaki K. Cerebrospinal fluid dynamics in idiopathic normal pressure hydrocephalus on four-dimensional flow imaging. Eur Radiol 2020; 30:4454-4465. [PMID: 32246220 DOI: 10.1007/s00330-020-06825-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/27/2020] [Accepted: 03/19/2020] [Indexed: 01/18/2023]
Abstract
OBJECTIVES To evaluate complex CSF movements and shear stress in patients with idiopathic normal pressure hydrocephalus (iNPH) on four-dimensional (4D) flow MRI. METHODS Three-dimensional velocities and volumes of the reciprocating CSF movements through 12 ROIs from the foramen of Monro to the upper cervical spine were measured in 41 patients with iNPH, 23 patients with co-occurrence of iNPH and Alzheimer's disease (AD), and 9 age-matched controls, using 4D flow imaging and application. Stroke volume, reversed-flow rate, and shear stress were automatically calculated. Relationships between flow-related parameters and morphological measurements were also assessed. RESULTS Stroke volumes, reversed-flow rates, and shear stress at the cerebral aqueduct were significantly higher in patients with iNPH than in controls. Patients with pure iNPH had significantly higher shear stress at the ventral aspect of the cerebral aqueduct than those with co-occurrence of iNPH and AD. The stroke volume at the upper end of the cerebral aqueduct had the strongest association with the anteroposterior diameter of the lower end of the cerebral aqueduct (r = 0.52). The stroke volume at the foramen of Monro had significant associations with the indices specific to iNPH. The shear stress at the dorsal aspect of the cerebral aqueduct had the strongest association with the diameter of the foramen of Magendie (r = 0.52). CONCLUSIONS Stroke volumes, reversed-flow rates, and shear stress through the cerebral aqueduct on 4D flow MRI are useful parameters for iNPH diagnosis. These findings can aid in elucidating the mechanism of ventricular enlargement in iNPH. KEY POINTS • The CSF stroke volume and bimodal shear stress at the cerebral aqueduct were considerably higher in patients with iNPH. • The patients with pure iNPH had significantly higher shear stress at the ventral aspect of the cerebral aqueduct than those with co-occurrence of iNPH and AD. • The shear stress at the cerebral aqueduct was significantly associated with the diameter of the foramen of Magendie.
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Affiliation(s)
- Shigeki Yamada
- Department of Neurosurgery, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan. .,Department of Neurosurgery and Normal Pressure Hydrocephalus Center, Rakuwakai Otowa Hospital, Kyoto, Japan. .,Interfaculty Initiative in Information Studies/Institute of Industrial Science, The University of Tokyo, Tokyo, Japan.
| | - Masatsune Ishikawa
- Department of Neurosurgery and Normal Pressure Hydrocephalus Center, Rakuwakai Otowa Hospital, Kyoto, Japan.,Rakuwa Villa Ilios, Kyoto, Japan
| | - Hirotaka Ito
- Medical System Research & Development Center, FUJIFILM Corporation, Tokyo, Japan
| | - Kazuo Yamamoto
- Department of Neurosurgery and Normal Pressure Hydrocephalus Center, Rakuwakai Otowa Hospital, Kyoto, Japan
| | - Makoto Yamaguchi
- Department of Neurosurgery and Normal Pressure Hydrocephalus Center, Rakuwakai Otowa Hospital, Kyoto, Japan
| | - Marie Oshima
- Interfaculty Initiative in Information Studies/Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Kazuhiko Nozaki
- Department of Neurosurgery, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan
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Khani M, Sass LR, Sharp MK, McCabe AR, Zitella Verbick LM, Lad SP, Martin BA. In vitro and numerical simulation of blood removal from cerebrospinal fluid: comparison of lumbar drain to Neurapheresis therapy. Fluids Barriers CNS 2020; 17:23. [PMID: 32178689 PMCID: PMC7077023 DOI: 10.1186/s12987-020-00185-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 03/06/2020] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Blood removal from cerebrospinal fluid (CSF) in post-subarachnoid hemorrhage patients may reduce the risk of related secondary brain injury. We formulated a computational fluid dynamics (CFD) model to investigate the impact of a dual-lumen catheter-based CSF filtration system, called Neurapheresis™ therapy, on blood removal from CSF compared to lumbar drain. METHODS A subject-specific multiphase CFD model of CSF system-wide solute transport was constructed based on MRI measurements. The Neurapheresis catheter geometry was added to the model within the spinal subarachnoid space (SAS). Neurapheresis flow aspiration and return rate was 2.0 and 1.8 mL/min, versus 0.2 mL/min drainage for lumbar drain. Blood was modeled as a bulk fluid phase within CSF with a 10% initial tracer concentration and identical viscosity and density as CSF. Subject-specific oscillatory CSF flow was applied at the model inlet. The dura and spinal cord geometry were considered to be stationary. Spatial-temporal tracer concentration was quantified based on time-average steady-streaming velocities throughout the domain under Neurapheresis therapy and lumbar drain. To help verify CFD results, an optically clear in vitro CSF model was constructed with fluorescein used as a blood surrogate. Quantitative comparison of numerical and in vitro results was performed by linear regression of spatial-temporal tracer concentration over 24-h. RESULTS After 24-h, tracer concentration was reduced to 4.9% under Neurapheresis therapy compared to 6.5% under lumbar drain. Tracer clearance was most rapid between the catheter aspiration and return ports. Neurapheresis therapy was found to have a greater impact on steady-streaming compared to lumbar drain. Steady-streaming in the cranial SAS was ~ 50× smaller than in the spinal SAS for both cases. CFD results were strongly correlated with the in vitro spatial-temporal tracer concentration under Neurapheresis therapy (R2 = 0.89 with + 2.13% and - 1.93% tracer concentration confidence interval). CONCLUSION A subject-specific CFD model of CSF system-wide solute transport was used to investigate the impact of Neurapheresis therapy on tracer removal from CSF compared to lumbar drain over a 24-h period. Neurapheresis therapy was found to substantially increase tracer clearance compared to lumbar drain. The multiphase CFD results were verified by in vitro fluorescein tracer experiments.
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Affiliation(s)
- Mohammadreza Khani
- Department of Biological Engineering, The University of Idaho, 875 Perimeter Drive, MS 0904, Moscow, ID, 83844-0904, USA
| | - Lucas R Sass
- Department of Biological Engineering, The University of Idaho, 875 Perimeter Drive, MS 0904, Moscow, ID, 83844-0904, USA
| | - M Keith Sharp
- Department of Mechanical Engineering, University of Louisville, 332 Eastern Pkwy, Louisville, KY, 40292, USA
| | - Aaron R McCabe
- Minnetronix Neuro, Inc., 1635 Energy Park Dr, Saint Paul, MN, 55108, USA
| | | | - Shivanand P Lad
- Department of Neurosurgery, Duke University School of Medicine, 3100 Tower Blvd, Durham, NC, 27707, USA
| | - Bryn A Martin
- Department of Biological Engineering, The University of Idaho, 875 Perimeter Drive, MS 0904, Moscow, ID, 83844-0904, USA.
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Chatterjee K, Carman-Esparza CM, Munson JM. Methods to measure, model and manipulate fluid flow in brain. J Neurosci Methods 2020; 333:108541. [PMID: 31838183 PMCID: PMC7607555 DOI: 10.1016/j.jneumeth.2019.108541] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/01/2019] [Accepted: 12/04/2019] [Indexed: 01/15/2023]
Abstract
The brain consists of a complex network of cells and matrix that is cushioned and nourished by multiple types of fluids: cerebrospinal fluid, blood, and interstitial fluid. The movement of these fluids through the tissues has recently gained more attention due to implications in Alzheimer's Disease and glioblastoma. Therefore, methods to study these fluid flows are necessary and timely for the current study of neuroscience. Imaging modalities such as magnetic resonance imaging have been used clinically and pre-clinically to image flows in healthy and diseased brains. These measurements have been used to both parameterize and validate models of fluid flow both computational and in vitro. Both of these models can elucidate the changes to fluid flow that occur during disease and can assist in linking the compartments of fluid flow with one another, a difficult challenge experimentally. In vitro models, though in limited use with fluid flow, allow the examination of cellular responses to physiological flow. To determine causation, in vivo methods have been developed to manipulate flow, including both physical and pharmacological manipulations, at each point of fluid movement of origination resulting in exciting findings in the preclinical setting. With new targets, such as the brain-draining lymphatics and glymphatic system, fluid flow and tissue drainage within the brain is an exciting and growing research area. In this review, we discuss the methods that currently exist to examine and test hypotheses related to fluid flow in the brain as we attempt to determine its impact on neural function.
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Affiliation(s)
- Krishnashis Chatterjee
- Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Cora M Carman-Esparza
- Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Jennifer M Munson
- Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States.
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Perivascular spaces in the brain: anatomy, physiology and pathology. Nat Rev Neurol 2020; 16:137-153. [PMID: 32094487 DOI: 10.1038/s41582-020-0312-z] [Citation(s) in RCA: 391] [Impact Index Per Article: 97.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2020] [Indexed: 02/06/2023]
Abstract
Perivascular spaces include a variety of passageways around arterioles, capillaries and venules in the brain, along which a range of substances can move. Although perivascular spaces were first identified over 150 years ago, they have come to prominence recently owing to advances in knowledge of their roles in clearance of interstitial fluid and waste from the brain, particularly during sleep, and in the pathogenesis of small vessel disease, Alzheimer disease and other neurodegenerative and inflammatory disorders. Experimental advances have facilitated in vivo studies of perivascular space function in intact rodent models during wakefulness and sleep, and MRI in humans has enabled perivascular space morphology to be related to cognitive function, vascular risk factors, vascular and neurodegenerative brain lesions, sleep patterns and cerebral haemodynamics. Many questions about perivascular spaces remain, but what is now clear is that normal perivascular space function is important for maintaining brain health. Here, we review perivascular space anatomy, physiology and pathology, particularly as seen with MRI in humans, and consider translation from models to humans to highlight knowns, unknowns, controversies and clinical relevance.
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125
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Piotrowska A, Winter K, Carare RO, Bechmann I. Vital Functions Contribute to the Spread of Extracellular Fluids in the Brain: Comparison Between Life and Death. Front Aging Neurosci 2020; 12:15. [PMID: 32116648 PMCID: PMC7027336 DOI: 10.3389/fnagi.2020.00015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 01/16/2020] [Indexed: 12/25/2022] Open
Abstract
Vascular pulsations, contractions of vascular smooth muscle cells and breathing have been reported to foster movement and clearance of interstitial and cerebrospinal fluids from the brain. The aim of this study was to estimate the contribution of these vital functions. We compared the spread of an injected hydrophilic tracer (Fluoro-Emerald, a 10 kDa fluorescein-coupled dextran amine) in the brains of live anesthetized and sacrificed rats at 30 and 90 min after injection. To determine the overall pattern of distribution of tracers, we created 3D-reconstructions of the horizontal transections of the whole brain. Immunofluorescence staining with laminin and collagen IV was performed to determine the pattern of distribution of tracer in relation to the cerebrovascular basement membranes. We found that diffusion was widely restricted to the periventricular region in sacrificed rats with no spread to the contralateral hemisphere, while the bulk flow occurred along the vasculature and reached the surface and the contralateral hemisphere as soon as 30 min after injection in live anesthetized animals. The tracer appeared to be localized along the vascular basement membranes and along fiber tracts as reported previously. Thus, our data indicate that vital functions are essential for the remote movement of extracellular fluids within the cerebral parenchyma.
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Affiliation(s)
| | - Karsten Winter
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Roxana O Carare
- Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Leipzig, Germany
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126
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Symptomatic psychosis risk and physiological fluctuation in functional MRI data. Schizophr Res 2020; 216:339-346. [PMID: 31810761 DOI: 10.1016/j.schres.2019.11.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 10/11/2019] [Accepted: 11/19/2019] [Indexed: 01/30/2023]
Abstract
BACKGROUND Physiological brain pulsations have been shown to play a critical role in maintaining interstitial homeostasis in the glymphatic brain clearance mechanism. We investigated whether psychotic symptomatology is related to the physiological variation of the human brain using fMRI. METHODS The participants (N = 277) were from the Northern Finland Birth Cohort 1986. Psychotic symptoms were evaluated with the Positive Symptoms Scale of the Structured Interview for Prodromal Syndromes (SIPS). We used the coefficient of variation of BOLD signal (CVBOLD) as a proxy for physiological brain pulsatility. The CVBOLD-analyses were controlled for motion, age, sex, and educational level. The results were also compared with fMRI and voxel-based morphometry (VBM) meta-analyses of schizophrenia patients (data from the Brainmap database). RESULTS At the global level, participants with psychotic-like symptoms had higher CVBOLD in cerebrospinal fluid (CSF) and white matter (WM), when compared to participants with no psychotic symptoms. Voxel-wise analyses revealed that CVBOLD was increased, especially in periventricular white matter, basal ganglia, cerebellum and parts of the cortical structures. Those brain regions, which included alterations of physiological fluctuation in symptomatic psychosis risk, overlapped <6% with the regions that were found to be affected in the meta-analyses of previous fMRI and VBM studies in schizophrenia patients. Motion did not vary as a function of SIPS. CONCLUSIONS Psychotic-like symptoms were associated with elevated CVBOLD in a variety of brain regions. The CVBOLD findings may produce new information about cerebral physiological fluctuations that have been out of reach in previous fMRI and VBM studies.
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127
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Khani M, Sass LR, McCabe AR, Zitella Verbick LM, Lad SP, Sharp MK, Martin BA. Impact of Neurapheresis System on Intrathecal Cerebrospinal Fluid Dynamics: A Computational Fluid Dynamics Study. J Biomech Eng 2020; 142:021006. [PMID: 31343659 PMCID: PMC7104775 DOI: 10.1115/1.4044308] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 07/18/2019] [Indexed: 11/08/2022]
Abstract
It has been hypothesized that early and rapid filtration of blood from cerebrospinal fluid (CSF) in postsubarachnoid hemorrhage patients may reduce hospital stay and related adverse events. In this study, we formulated a subject-specific computational fluid dynamics (CFD) model to parametrically investigate the impact of a novel dual-lumen catheter-based CSF filtration system, the Neurapheresis™ system (Minnetronix Neuro, Inc., St. Paul, MN), on intrathecal CSF dynamics. The operating principle of this system is to remove CSF from one location along the spine (aspiration port), externally filter the CSF routing the retentate to a waste bag, and return permeate (uncontaminated CSF) to another location along the spine (return port). The CFD model allowed parametric simulation of how the Neurapheresis system impacts intrathecal CSF velocities and steady-steady streaming under various Neurapheresis flow settings ranging from 0.5 to 2.0 ml/min and with a constant retentate removal rate of 0.2 ml/min simulation of the Neurapheresis system were compared to a lumbar drain simulation with a typical CSF removal rate setting of 0.2 ml/min. Results showed that the Neurapheresis system at a maximum flow of 2.0 ml/min increased average steady streaming CSF velocity 2× in comparison to lumbar drain (0.190 ± 0.133 versus 0.093 ± 0.107 mm/s, respectively). This affect was localized to the region within the Neurapheresis flow loop. The mean velocities introduced by the flow loop were relatively small in comparison to normal cardiac-induced CSF velocities.
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Affiliation(s)
- Mohammadreza Khani
- Department of Biological Engineering, University of Idaho, Moscow, ID 83844
| | - Lucas R. Sass
- Department of Biological Engineering, University of Idaho, Moscow, ID 83844
| | | | | | - Shivanand P. Lad
- Department of Neurosurgery, Duke University School of Medicine, Durham, NC 27710
| | - M. Keith Sharp
- Department of Mechanical Engineering, University of Louisville, Louisville, KY 40292
| | - Bryn A. Martin
- Department of Biological Engineering, University of Idaho, Moscow, ID 83844
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128
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Saarinen A, Lieslehto J, Kiviniemi V, Tuovinen T, Veijola J, Hintsanen M. The relationship of genetic susceptibilities for psychosis with physiological fluctuation in functional MRI data. Psychiatry Res Neuroimaging 2020; 297:111031. [PMID: 32035357 DOI: 10.1016/j.pscychresns.2020.111031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 01/15/2020] [Accepted: 01/17/2020] [Indexed: 11/18/2022]
Abstract
Previously, schizophrenia is found to be related to the variability of the functional magnetic resonance imaging (fMRI) signal in the white matter. However, evidence about the relationship between genetic vulnerabilities and physiological fluctuation in the brain is lacking. We investigated whether familial risk for psychosis (FR) and polygenic risk score for schizophrenia (PRS) are linked with physiological fluctuation in fMRI data. We used data from the Oulu Brain and Mind study (n = 140-149, aged 20-24 years) that is a substudy of the Northern Finland Birth Cohort 1986. The participants underwent a resting-state fMRI scan. Coefficient of variation (CV) of blood oxygen level dependent (BOLD) signal (CVBOLD) was used as a proxy of physiological fluctuation in the brain. Familial risk was defined to be present if at least one parent had been diagnosed with psychosis previously. PRS was computed based on the results of the prior GWAS by the Schizophrenia Working Group. FR or PRS were not associated with CVBOLD in cerebrospinal fluid, white matter, or grey matter. The findings did not provide evidence for the previous suggestions that genetic vulnerabilities for schizophrenia become apparent in alterations of the variation of the BOLD signal in the brain.
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Affiliation(s)
- Aino Saarinen
- Research Unit of Psychology, University of Oulu, Finland; Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Finland; Research Unit of Clinical Neuroscience, Department of Psychiatry, University of Oulu.
| | - Johannes Lieslehto
- Section for Neurodiagnostic Applications, Department of Psychiatry, Ludwig Maximilian University, Nussbaumstrasse 7, 80336 Munich, Bavaria, Germany; Center for Life Course Health Research, University of Oulu, Finland
| | - Vesa Kiviniemi
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland; Department of Psychiatry, Oulu University Hospital, Oulu, Finland
| | - Timo Tuovinen
- Research Unit of Clinical Neuroscience, Department of Psychiatry, University of Oulu
| | - Juha Veijola
- Research Unit of Clinical Neuroscience, Department of Psychiatry, University of Oulu; Department of Psychiatry, Oulu University Hospital, Oulu, Finland; Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
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129
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Sloots JJ, Biessels GJ, Zwanenburg JJM. Cardiac and respiration-induced brain deformations in humans quantified with high-field MRI. Neuroimage 2020; 210:116581. [PMID: 31982580 DOI: 10.1016/j.neuroimage.2020.116581] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 12/23/2019] [Accepted: 01/20/2020] [Indexed: 01/20/2023] Open
Abstract
Microvascular blood volume pulsations due to the cardiac and respiratory cycles induce brain tissue deformation and, as such, are considered to drive the brain's waste clearance system. We have developed a high-field magnetic resonance imaging (MRI) technique to quantify both cardiac and respiration-induced tissue deformations, which could not be assessed noninvasively before. The technique acquires motion encoded snapshot images in which various forms of motion and confounders are entangled. First, we optimized the motion sensitivity for application in the human brain. Next, we isolated the heartbeat and respiration-related deformations, by introducing a linear model that fits the snapshot series to the recorded physiological information. As a result, we obtained maps of the physiological tissue deformation with 3mm isotropic spatial resolution. Heartbeat and respiration-induced volumetric strain were significantly different from zero in the basal ganglia (median (25-75% interquartile range): 0.85·10-3 (0.39·10-3-1.05·10-3), p = 0.0008 and -0.28·10-3 (-0.41·10-3-0.06·10-3), p = 0.047, respectively. Smaller volumetric strains were observed in the white matter of the centrum semi ovale (0.28·10-3 (0-0.59·10-3) and -0.06·10-3 (-0.17·10-3-0.20·10-3)), which was only significant for the heartbeat (p = 0.02 and p = 0.7, respectively). Furthermore, heartbeat-induced volumetric strain was about three times larger than respiration-induced volumetric strain. This technique opens a window on the driving forces of the human brain clearance system.
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130
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Eichele G, Bodenschatz E, Ditte Z, Günther AK, Kapoor S, Wang Y, Westendorf C. Cilia-driven flows in the brain third ventricle. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190154. [PMID: 31884922 DOI: 10.1098/rstb.2019.0154] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The brain ventricles are interconnected, elaborate cavities that traverse the brain. They are filled with cerebrospinal fluid (CSF) that is, to a large part, produced by the choroid plexus, a secretory epithelium that reaches into the ventricles. CSF is rich in cytokines, growth factors and extracellular vesicles that glide along the walls of ventricles, powered by bundles of motile cilia that coat the ventricular wall. We review the cellular and biochemical properties of the ventral part of the third ventricle that is surrounded by the hypothalamus. In particular, we consider the recently discovered intricate network of cilia-driven flows that characterize this ventricle and discuss the potential physiological significance of this flow for the directional transport of CSF signals to cellular targets located either within the third ventricle or in the adjacent hypothalamic brain parenchyma. Cilia-driven streams of signalling molecules offer an exciting perspective on how fluid-borne signals are dynamically transmitted in the brain. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
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Affiliation(s)
- Gregor Eichele
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Eberhard Bodenschatz
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
| | - Zuzana Ditte
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Ann-Kathrin Günther
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Shoba Kapoor
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Yong Wang
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
| | - Christian Westendorf
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
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131
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Ringers C, Olstad EW, Jurisch-Yaksi N. The role of motile cilia in the development and physiology of the nervous system. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190156. [PMID: 31884916 DOI: 10.1098/rstb.2019.0156] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Motile cilia are miniature, whip-like organelles whose beating generates a directional fluid flow. The flow generated by ciliated epithelia is a subject of great interest, as defective ciliary motility results in severe human diseases called motile ciliopathies. Despite the abundance of motile cilia in diverse organs including the nervous system, their role in organ development and homeostasis remains poorly understood. Recently, much progress has been made regarding the identity of motile ciliated cells and the role of motile-cilia-mediated flow in the development and physiology of the nervous system. In this review, we will discuss these recent advances from sensory organs, specifically the nose and the ear, to the spinal cord and brain ventricles. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
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Affiliation(s)
- Christa Ringers
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Olav Kyrres Gate 9, 7030 Trondheim, Norway
| | - Emilie W Olstad
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Olav Kyrres Gate 9, 7030 Trondheim, Norway
| | - Nathalie Jurisch-Yaksi
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Olav Kyrres Gate 9, 7030 Trondheim, Norway.,Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Olav Kyrres Gate 9, 7030 Trondheim, Norway.,Department of Neurology and Clinical Neurophysiology, St Olavs University Hospital, Edvard Griegs Gate 8, 7030 Trondheim, Norway
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132
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Benveniste H, Heerdt PM, Fontes M, Rothman DL, Volkow ND. Glymphatic System Function in Relation to Anesthesia and Sleep States. Anesth Analg 2019; 128:747-758. [PMID: 30883420 DOI: 10.1213/ane.0000000000004069] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The brain is one of the most metabolically active organs in the body. The brain's high energy demand associated with wakefulness persists during rapid eye movement sleep, and even during non-rapid eye movement sleep, cerebral oxygen consumption is only reduced by 20%. The active bioenergetic state parallels metabolic waste production at a higher rate than in other organs, and the lack of lymphatic vasculature in brain parenchyma is therefore a conundrum. A common assumption has been that with a tight blood-brain barrier restricting solute and fluid movements, a lymphatic system is superfluous in the central nervous system. Cerebrospinal fluid (CSF) flow has long been thought to facilitate central nervous system tissue "detoxification" in place of lymphatics. Nonetheless, while CSF production and transport have been studied for decades, the exact processes involved in toxic waste clearance remain poorly understood. Over the past 5 years, emerging data have begun to shed new light on these processes in the form of the "glymphatic system," a novel brain-wide perivascular transit passageway dedicated to CSF transport and metabolic waste drainage from the brain. Here, we review the key anatomical components and operational drivers of the brain's glymphatic system, with a focus on its unique functional dependence on the state of arousal and anesthetic regimens. We also discuss evidence for why clinical exploration of this novel system may in the future provide valuable insight into new strategies for preventing delirium and cognitive dysfunction in perioperative and critical care settings.
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Affiliation(s)
| | | | | | - Douglas L Rothman
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut
| | - Nora D Volkow
- Laboratory for Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland
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133
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Intracranial pressure in the American Alligator (Alligator mississippiensis): reptilian meninges and orthostatic gradients. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 206:45-54. [PMID: 31807848 DOI: 10.1007/s00359-019-01386-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 11/16/2019] [Accepted: 11/26/2019] [Indexed: 10/25/2022]
Abstract
The cranial meninges of reptiles differ from the more widely studied mammalian pattern in that the intraventricular and subarachnoid spaces are, at least partially, isolated. This study was undertaken to investigate the bulk flow of cerebrospinal fluid, and the resulting changes in intracranial pressure, in a common reptilian species. Intracranial pressure was measured using ocular ultrasonography and by surgically implanting pressure cannulae into the cranial subarachnoid space. The system was then challenged by: rotating the animal to create orthostatic gradients, perturbation of the vascular system, administration of epinephrine, and cephalic cutaneous heating. Pressure changes determined from the implanted catheters and through quantification of the optic nerve sheath were highly correlated and showed a significant linear relationship with orthostatic gradients. The catheter pressure responses were phasic, with an initial rapid response followed by a much slower response; each phase accounted for roughly half of the total pressure change. No significant relationship was found between intracranial pressure and either heart rate or blood flow. The focal application of heat and the administration of epinephrine both increased intracranial pressure, the latter influence being particularly pronounced.
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134
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Ma Q, Decker Y, Müller A, Ineichen BV, Proulx ST. Clearance of cerebrospinal fluid from the sacral spine through lymphatic vessels. J Exp Med 2019; 216:2492-2502. [PMID: 31455602 PMCID: PMC6829589 DOI: 10.1084/jem.20190351] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 05/16/2019] [Accepted: 07/23/2019] [Indexed: 01/12/2023] Open
Abstract
The pathways of circulation and clearance of cerebrospinal fluid (CSF) in the spine have yet to be elucidated. We have recently shown with dynamic in vivo imaging that routes of outflow of CSF in mice occur along cranial nerves to extracranial lymphatic vessels. Here, we use near-infrared and magnetic resonance imaging to demonstrate the flow of CSF tracers within the spinal column and reveal the major spinal pathways for outflow to lymphatic vessels in mice. We found that after intraventricular injection, a spread of CSF tracers occurs within both the central canal and the spinal subarachnoid space toward the caudal end of the spine. Outflow of CSF tracers from the spinal subarachnoid space occurred predominantly from intravertebral regions of the sacral spine to lymphatic vessels, leading to sacral and iliac LNs. Clearance of CSF from the spine to lymphatic vessels may have significance for many conditions, including multiple sclerosis and spinal cord injury.
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Affiliation(s)
- Qiaoli Ma
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Yann Decker
- Department of Neurology, University of the Saarland, Homburg, Germany
| | - Andreas Müller
- Clinic for Diagnostic and Interventional Radiology, University of the Saarland, Homburg, Germany
| | | | - Steven T Proulx
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
- Theodor Kocher Institute, University of Bern, Bern, Switzerland
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135
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Winklewski PJ, Wolf J, Gruszecki M, Wszedybyl-Winklewska M, Narkiewicz K. Current understanding of the effects of inspiratory resistance on the interactions between systemic blood pressure, cerebral perfusion, intracranial pressure, and cerebrospinal fluid dynamics. J Appl Physiol (1985) 2019; 127:1206-1214. [DOI: 10.1152/japplphysiol.00058.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Negative intrathoracic pressure (nITP) is generated by the respiratory muscles during inspiration to overcome inspiratory resistance, thus enabling lung ventilation. Recently developed noninvasive techniques have made it possible to assess the effects of nITP in real time in several physiological aspects such as systemic blood pressure (BP), intracranial pressure (ICP), and cerebral blood flow (CBF). It has been shown that nITP from 0 to −20 cmH2O elevates BP and diminishes ICP, which facilitates brain perfusion. The effects of nITP from −20 to −40 cmH2O on BP, ICP, and CBF remain largely unrecognized, yet even nITP at −40 cmH2O may facilitate CBF by diminishing ICP. Importantly, nITP from −20 to −40 cmH2O has been documented in adults in commonly encountered obstructive sleep apnea, which justifies research in this area. Recent revelations about interactions between ICP and BP have opened up new fields of research in physiological regulation and the pathophysiology of common diseases, such as hypertension, brain injury, and respiratory disorders. A better understanding of these interactions may translate directly into new therapies in various fields of clinical medicine.
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Affiliation(s)
- Pawel J. Winklewski
- Department of Human Physiology, Medical University of Gdansk, Gdansk, Poland
- Department of Clinical Anatomy and Physiology, Pomeranian University of Slupsk, Slupsk, Poland
| | - Jacek Wolf
- Department of Hypertension and Diabetology, Medical University of Gdansk, Gdansk, Poland
| | - Marcin Gruszecki
- Department of Radiology Informatics and Statistics, Medical University of Gdansk, Gdansk, Poland
| | | | - Krzysztof Narkiewicz
- Department of Hypertension and Diabetology, Medical University of Gdansk, Gdansk, Poland
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136
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Fultz NE, Bonmassar G, Setsompop K, Stickgold RA, Rosen BR, Polimeni JR, Lewis LD. Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep. Science 2019; 366:628-631. [PMID: 31672896 PMCID: PMC7309589 DOI: 10.1126/science.aax5440] [Citation(s) in RCA: 491] [Impact Index Per Article: 98.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 09/18/2019] [Indexed: 12/14/2022]
Abstract
Sleep is essential for both cognition and maintenance of healthy brain function. Slow waves in neural activity contribute to memory consolidation, whereas cerebrospinal fluid (CSF) clears metabolic waste products from the brain. Whether these two processes are related is not known. We used accelerated neuroimaging to measure physiological and neural dynamics in the human brain. We discovered a coherent pattern of oscillating electrophysiological, hemodynamic, and CSF dynamics that appears during non-rapid eye movement sleep. Neural slow waves are followed by hemodynamic oscillations, which in turn are coupled to CSF flow. These results demonstrate that the sleeping brain exhibits waves of CSF flow on a macroscopic scale, and these CSF dynamics are interlinked with neural and hemodynamic rhythms.
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Affiliation(s)
- Nina E Fultz
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
| | - Kawin Setsompop
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
| | - Robert A Stickgold
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115, USA
| | - Bruce R Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jonathan R Polimeni
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
| | - Laura D Lewis
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02129, USA
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137
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Thomas JH. Fluid dynamics of cerebrospinal fluid flow in perivascular spaces. J R Soc Interface 2019; 16:20190572. [PMID: 31640500 PMCID: PMC6833335 DOI: 10.1098/rsif.2019.0572] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/02/2019] [Indexed: 01/13/2023] Open
Abstract
The flow of cerebrospinal fluid along perivascular spaces (PVSs) is an important part of the brain's system for delivering nutrients and eliminating metabolic waste products (such as amyloid-β); it also offers a pathway for the delivery of therapeutic drugs to the brain parenchyma. Recent experimental results have resolved several important questions about this flow, setting the stage for advances in our understanding of its fluid dynamics. This review summarizes the new experimental evidence and provides a critical evaluation of previous fluid-dynamic models of flows in PVSs. The review also discusses some basic fluid-dynamic concepts relevant to these flows, including the combined effects of diffusion and advection in clearing solutes from the brain.
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Affiliation(s)
- John H. Thomas
- Department of Mechanical Engineering, University of Rochester, Rochester, NY 14627, USA
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138
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Raz E, Dehkharghani S, Shapiro M, Nossek E, Jain R, Zhang C, Ishida K, Tanweer O, Peschillo S, Nelson PK. Possible Empirical Evidence of Glymphatic System on Computed Tomography After Endovascular Perforations. World Neurosurg 2019; 134:e400-e404. [PMID: 31655242 DOI: 10.1016/j.wneu.2019.10.089] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/13/2019] [Accepted: 10/14/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND The glial-lymphatic pathway is a fluid-clearance pathway consisting of a para-arterial route for the flow of cerebrospinal fluid along perivascular spaces and subsequently toward the brain interstitium. In this case series, we aim to investigate an empirical demonstration of glymphatic clearance of extravasated iodine following perforation incurred during endovascular therapy on serial computed tomography. METHODS Six consecutive cases of endovascular perforation during thrombectomy performed between 2005 and 2018 were retrospectively collected by searching our internal database of total 446 thrombectomies. Two cases were excluded because care was withdrawn shortly following the procedure and no follow-up imaging was available. One case was excluded because a ventricular drain was placed. Three cases were hence included in this analysis. RESULTS All 3 cases demonstrated progressive absorption of contrast by the brain parenchyma with eventual contrast disappearance. CONCLUSIONS We described a likely in vivo computed tomography correlate of the glymphatic system in a cohort of patients who sustained intraprocedural extravasation during thrombectomy for acute ischemic stroke.
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Affiliation(s)
- Eytan Raz
- Department of Radiology, NYU Langone Health, New York, New York, USA.
| | | | - Maksim Shapiro
- Department of Radiology, NYU Langone Health, New York, New York, USA
| | - Erez Nossek
- Department of Neurosurgery, NYU Langone Health, New York, New York, USA
| | - Rajan Jain
- Department of Radiology, NYU Langone Health, New York, New York, USA; Department of Neurosurgery, NYU Langone Health, New York, New York, USA
| | - Cen Zhang
- Department of Neurology, NYU Langone Health, New York, New York, USA
| | - Koto Ishida
- Department of Neurology, NYU Langone Health, New York, New York, USA
| | - Omar Tanweer
- Department of Neurosurgery, NYU Langone Health, New York, New York, USA
| | - Simone Peschillo
- Department of Neurosurgery, University of Catania, Catania, Sicily, Italy
| | - Peter Kim Nelson
- Department of Radiology, NYU Langone Health, New York, New York, USA; Department of Neurosurgery, NYU Langone Health, New York, New York, USA
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139
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Stine CA, Munson JM. Convection-Enhanced Delivery: Connection to and Impact of Interstitial Fluid Flow. Front Oncol 2019; 9:966. [PMID: 31632905 PMCID: PMC6783516 DOI: 10.3389/fonc.2019.00966] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 09/11/2019] [Indexed: 01/08/2023] Open
Abstract
Convection-enhanced delivery (CED) is a method used to increase transport of therapeutics in and around brain tumors. CED works through locally applying a pressure differential to drive fluid flow throughout the tumor, such that convective forces dominate over diffusive transport. This allows therapies to bypass the blood brain barrier that would otherwise be too large or solely rely on passive diffusion. However, this also drives fluid flow out through the tumor bulk into surrounding brain parenchyma, which results in increased interstitial fluid (IF) flow, or fluid flow within extracellular spaces in the tissue. IF flow has been associated with altered transport of molecules, extracellular matrix rearrangement, and triggering of cellular motility through a number of mechanisms. Thus, the results of a simple method to increase drug delivery may have unintended consequences on tissue morphology. Clinically, prediction of dispersal of agents via CED is important to catheter design, placement, and implementation to optimize contact of tumor cells with therapeutic agent. Prediction software can aid in this problem, yet we wonder if there is a better way to predict therapeutic distribution based simply on IF flow pathways as determined from pre-intervention imaging. Overall, CED based therapy has seen limited success and we posit that integration and appreciation of altered IF flow may enhance outcomes. Thus, in this manuscript we both review the current state of the art in CED and IF flow mechanistic understanding and relate these two elements to each other in a clinical context.
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Affiliation(s)
| | - Jennifer M. Munson
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
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140
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Noble DJ, Hochman S. Hypothesis: Pulmonary Afferent Activity Patterns During Slow, Deep Breathing Contribute to the Neural Induction of Physiological Relaxation. Front Physiol 2019; 10:1176. [PMID: 31572221 PMCID: PMC6753868 DOI: 10.3389/fphys.2019.01176] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 08/30/2019] [Indexed: 12/26/2022] Open
Abstract
Control of respiration provides a powerful voluntary portal to entrain and modulate central autonomic networks. Slowing and deepening breathing as a relaxation technique has shown promise in a variety of cardiorespiratory and stress-related disorders, but few studies have investigated the physiological mechanisms conferring its benefits. Recent evidence suggests that breathing at a frequency near 0.1 Hz (6 breaths per minute) promotes behavioral relaxation and baroreflex resonance effects that maximize heart rate variability. Breathing around this frequency appears to elicit resonant and coherent features in neuro-mechanical interactions that optimize physiological function. Here we explore the neurophysiology of slow, deep breathing and propose that coincident features of respiratory and baroreceptor afferent activity cycling at 0.1 Hz entrain central autonomic networks. An important role is assigned to the preferential recruitment of slowly-adapting pulmonary afferents (SARs) during prolonged inhalations. These afferents project to discrete areas in the brainstem within the nucleus of the solitary tract (NTS) and initiate inhibitory actions on downstream targets. Conversely, deep exhalations terminate SAR activity and activate arterial baroreceptors via increases in blood pressure to stimulate, through NTS projections, parasympathetic outflow to the heart. Reciprocal SAR and baroreceptor afferent-evoked actions combine to enhance sympathetic activity during inhalation and parasympathetic activity during exhalation, respectively. This leads to pronounced heart rate variability in phase with the respiratory cycle (respiratory sinus arrhythmia) and improved ventilation-perfusion matching. NTS relay neurons project extensively to areas of the central autonomic network to encode important features of the breathing pattern that may modulate anxiety, arousal, and attention. In our model, pronounced respiratory rhythms during slow, deep breathing also support expression of slow cortical rhythms to induce a functional state of alert relaxation, and, via nasal respiration-based actions on olfactory signaling, recruit hippocampal pathways to boost memory consolidation. Collectively, we assert that the neurophysiological processes recruited during slow, deep breathing enhance the cognitive and behavioral therapeutic outcomes obtained through various mind-body practices. Future studies are required to better understand the physio-behavioral processes involved, including in animal models that control for confounding factors such as expectancy biases.
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Affiliation(s)
- Donald J. Noble
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
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141
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Lee WJ, Jung KH, Ryu YJ, Kim JM, Lee ST, Chu K, Kim M, Lee SK, Roh JK. Association of Cardiac Hemodynamic Factors With Severity of White Matter Hyperintensities in Chronic Valvular Heart Disease. JAMA Neurol 2019; 75:80-87. [PMID: 29114731 DOI: 10.1001/jamaneurol.2017.2853] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Importance The cerebral white matter hyperintensity (WMH) is frequently noted in patients with chronic heart disease. Long-term alteration of cardiac hemodynamics might have an influence on the mechanism of cerebral WMH. Objective To investigate the association between chronically altered cardiac hemodynamics and severity of cerebral WMH in patients with chronic valvular heart disease. Design, Setting, and Participants This cross-sectional analysis identified 303 consecutive patients at a tertiary referral center between 2008 and 2016 who were 50 years or older, and diagnosed with severe chronic valvular heart disease and underwent cardiac catherization, echocardiography, and received brain magnetic resonance imaging. Among these patients, 71 with other demonstrated cardiac disease, central nervous system disease, and/or without sufficient catheterization data were excluded, and the remaining 232 patients were included in further analyses. Exposures The site and mechanism of valve diseases, as well as clinical and medication profiles, were reviewed. Cardiac catheterization parameters such as right atrial (RA) mean pressure, right ventricular pressure, and aortic mean pressure were obtained. Comprehensive echocardiographic hemodynamic markers such as left ventricular (LV) ejection fraction, LV mass index, LV end diastolic volume, cardiac index, and E/e' ratio were also obtained. Main Outcomes and Measures White matter hyperintensity volume was quantitatively evaluated using volumetric analysis. Results This study included 232 patients (103 men [44.4%] and 129 women [55.6%]; mean [SD] (range) age, 65.6 [8.8] (51-88) years) in the final analysis. The mean (SD) WMH volume was 5.93 (7.14) mL (median [interquartile range], 4.33 [1.33-8.62] mL), and mean (SD) RA pressure was 10.0 (4.7) mm Hg. From the catheterization data, 147 patients (63.4%) were classified as having a disease involving the mitral valve; 93 (40.1%), aortic valve; 37 (15.9%), tricuspid valve; and 4 (1.7%), pulmonary valve. In multivariate linear regression analysis, adjusting the type and mechanism of valve disease and clinical, echocardiographic, and/or other catheterization parameters, WMH volume was linearly associated with mean RA pressure (B coefficient, 0.702; 95% CI, 0.373-1.031; P = .001), along with age (B coefficient, 0.145; 95% CI, 0.029-0.261; P = .01) and mean aortic pressure (B coefficient, 0.112; 95% CI, 0.034-0.190; P = .005). Conclusions and Relevance Mean RA pressure was independently associated with the WMH volume in chronic valvular heart disease. Chronically altered RA hemodynamics might have a distinct influence on the pathomechanism underlying the development of WMH.
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Affiliation(s)
- Woo-Jin Lee
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
| | - Keun-Hwa Jung
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.,Program in Neuroscience, Neuroscience Research Institute of SNUMRC, College of Medicine, Seoul National University, Seoul, South Korea
| | - Young Jin Ryu
- Department of Radiology, Seoul National University Hospital, Seoul, South Korea
| | - Jeong-Min Kim
- Department of Neurology, Chung-Ang University Hospital, Seoul, South Korea
| | - Soon-Tae Lee
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.,Program in Neuroscience, Neuroscience Research Institute of SNUMRC, College of Medicine, Seoul National University, Seoul, South Korea
| | - Kon Chu
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.,Program in Neuroscience, Neuroscience Research Institute of SNUMRC, College of Medicine, Seoul National University, Seoul, South Korea
| | - Manho Kim
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.,Program in Neuroscience, Neuroscience Research Institute of SNUMRC, College of Medicine, Seoul National University, Seoul, South Korea.,Protein Metabolism Research Center, Seoul National University College of Medicine, Seoul, South Korea
| | - Sang Kun Lee
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.,Program in Neuroscience, Neuroscience Research Institute of SNUMRC, College of Medicine, Seoul National University, Seoul, South Korea
| | - Jae-Kyu Roh
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.,Department of Neurology, The Armed Forces Capital Hospital, Sungnam, South Korea
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142
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Rajna Z, Raitamaa L, Tuovinen T, Heikkila J, Kiviniemi V, Seppanen T. 3D Multi-Resolution Optical Flow Analysis of Cardiovascular Pulse Propagation in Human Brain. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:2028-2036. [PMID: 30892202 DOI: 10.1109/tmi.2019.2904762] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The brain is cleaned from waste by glymphatic clearance serving a similar purpose as the lymphatic system in the rest of the body. Impairment of the glymphatic brain clearance precedes protein accumulation and reduced cognitive function in Alzheimer's disease (AD). Cardiovascular pulsations are a primary driving force of the glymphatic brain clearance. We developed a method to quantify cardiovascular pulse propagation in the human brain with magnetic resonance encephalography (MREG). We extended a standard optical flow estimation method to three spatial dimensions, with a multi-resolution processing scheme. We added application-specific criteria for discarding inaccurate results. With the proposed method, it is now possible to estimate the propagation of cardiovascular pulse wavefronts from the whole brain MREG data sampled at 10 Hz. The results show that on average the cardiovascular pulse propagates from major arteries via cerebral spinal fluid spaces into all tissue compartments in the brain. We present an example, that cardiovascular pulsations are significantly altered in AD: coefficient of variation and sample entropy of the pulse propagation speed in the lateral ventricles change in AD. These changes are in line with the theory of glymphatic clearance impairment in AD. The proposed non-invasive method can assess a performance indicator related to the glymphatic clearance in the human brain.
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143
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Trumbore CN. Shear-Induced Amyloid Formation in the Brain: III. The Roles of Shear Energy and Seeding in a Proposed Shear Model. J Alzheimers Dis 2019; 65:47-70. [PMID: 30040710 PMCID: PMC6087447 DOI: 10.3233/jad-171003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
If cerebrospinal and interstitial fluids move through very narrow brain flow channels, these restrictive surroundings generate varying levels of fluid shear and different shear rates, and dissolved amyloid monomers absorb different shear energies. It is proposed that dissolved amyloid-β protein (Aβ) and other amyloid monomers undergo shear-induced conformational changes that ultimately lead to amyloid monomer aggregation even at very low brain flow and shear rates. Soluble Aβ oligomers taken from diseased brains initiate in vivo amyloid formation in non-diseased brains. The brain environment is apparently responsible for this result. A mechanism involving extensional shear is proposed for the formation of a seed Aβ monomer molecule that ultimately promotes templated conformational change of other Aβ molecules. Under non-quiescent, non-equilibrium conditions, gentle extensional shear within the brain parenchyma, and perhaps even during laboratory preparation of Aβ samples, may be sufficient to cause subtle conformational changes in these monomers. These result from brain processes that significantly lower the high activation energy predicted for the quiescent Aβ dimerization process. It is further suggested that changes in brain location and changes brought about by aging expose Aβ molecules to different shear rates, total shear, and types of shear, resulting in different conformational changes in these molecules. The consequences of such changes caused by variable shear energy are proposed to underlie formation of amyloid strains causing different amyloid diseases. Amyloid researchers are urged to undertake studies with amyloids, anti-amyloid drugs, and antibodies while all of these are under shear conditions similar to those in the brain.
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Affiliation(s)
- Conrad N Trumbore
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
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144
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Jain S, Malinowski M, Chopra P, Varshney V, Deer TR. Intrathecal drug delivery for pain management: recent advances and future developments. Expert Opin Drug Deliv 2019; 16:815-822. [PMID: 31305165 DOI: 10.1080/17425247.2019.1642870] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Introduction: Chronic pain conditions of malignant and non-malignant etiology afflict a large group of the population and pose a vast economic burden on society. Intrathecal drug therapy is a viable treatment option in such patients who have failed conservative medical measures and less invasive pain management procedures. However, the clinical growth of intrathecal therapy in managing intractable chronic pain conditions continues to face many challenges and is likely underutilized secondary to its high-complexity and lack of understanding. Areas covered: This review will briefly discuss the history of intrathecal drug delivery systems (IDDS), cerebrospinal fluid (CSF) flow dynamics, types of IDDS, indications and patient profile suitable for this therapy, and risks and complications related to IDDS. We will also discuss challenges faced by physicians utilizing this therapy and the future changes that are needed for making this treatment modality more efficacious. Expert opinion: IDDS offer an effective therapy for pain control in patients suffering from chronic intractable pain conditions. These devices provide a safer alternative to oral opioid medications with reduced systemic side effects. Adherence to best practices and continued clinical and basic science research is important to ensure continuing success of this therapy.
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Affiliation(s)
- Sameer Jain
- a Pain Treatment Centers of America , Little Rock , AR , USA
| | - Mark Malinowski
- b Ohio University - HCOM , OH , USA.,c Adena Spine Center , Chillicothe , OH , USA
| | - Pooja Chopra
- d Department of Physical Medicine and Rehabilitation, University of Kentucky , Lexington , KY , USA
| | - Vishal Varshney
- e Division of Pain Medicine, Department of Anesthesiology, University of Calgary , Calgary , AB , Canada
| | - Timothy R Deer
- f Spine and Nerve Center of the Virginias , Charleston , WV , USA
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145
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Vinje V, Ringstad G, Lindstrøm EK, Valnes LM, Rognes ME, Eide PK, Mardal KA. Respiratory influence on cerebrospinal fluid flow - a computational study based on long-term intracranial pressure measurements. Sci Rep 2019; 9:9732. [PMID: 31278278 PMCID: PMC6611841 DOI: 10.1038/s41598-019-46055-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 06/17/2019] [Indexed: 11/27/2022] Open
Abstract
Current theories suggest that waste solutes are cleared from the brain via cerebrospinal fluid (CSF) flow, driven by pressure pulsations of possibly both cardiac and respiratory origin. In this study, we explored the importance of respiratory versus cardiac pressure gradients for CSF flow within one of the main conduits of the brain, the cerebral aqueduct. We obtained overnight intracranial pressure measurements from two different locations in 10 idiopathic normal pressure hydrocephalus (iNPH) patients. The resulting pressure gradients were analyzed with respect to cardiac and respiratory frequencies and amplitudes (182,000 cardiac and 48,000 respiratory cycles). Pressure gradients were used to compute CSF flow in simplified and patient-specific models of the aqueduct. The average ratio between cardiac over respiratory flow volume was 0.21 ± 0.09, even though the corresponding ratio between the pressure gradient amplitudes was 2.85 ± 1.06. The cardiac cycle was 0.25 ± 0.04 times the length of the respiratory cycle, allowing the respiratory pressure gradient to build considerable momentum despite its small magnitude. No significant differences in pressure gradient pulsations were found in the sleeping versus awake state. Pressure gradients underlying CSF flow in the cerebral aqueduct are dominated by cardiac pulsations, but induce CSF flow volumes dominated by respiration.
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Affiliation(s)
- Vegard Vinje
- Department of Scientific Computing and Numerical Analysis, Simula Research Laboratory, 1325, Lysaker, Norway.
| | - Geir Ringstad
- Department of Radiology and Nuclear Medicine, Oslo University Hospital - Rikshospitalet, 0372, Oslo, Norway
| | | | | | - Marie E Rognes
- Department of Scientific Computing and Numerical Analysis, Simula Research Laboratory, 1325, Lysaker, Norway
| | - Per Kristian Eide
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 0315, Oslo, Norway.,Department of Neurosurgery, Oslo University Hospital - Rikshospitalet, 0372, Oslo, Norway
| | - Kent-Andre Mardal
- Department of Scientific Computing and Numerical Analysis, Simula Research Laboratory, 1325, Lysaker, Norway.,Department of Mathematics, University of Oslo, 0315, Oslo, Norway
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146
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Rasmussen MK, Mestre H, Nedergaard M. The glymphatic pathway in neurological disorders. Lancet Neurol 2019; 17:1016-1024. [PMID: 30353860 DOI: 10.1016/s1474-4422(18)30318-1] [Citation(s) in RCA: 769] [Impact Index Per Article: 153.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/14/2018] [Accepted: 08/20/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND The glymphatic (glial-lymphatic) pathway is a fluid-clearance pathway identified in the rodent brain in 2012. This pathway subserves the flow of CSF into the brain along arterial perivascular spaces and subsequently into the brain interstitium, facilitated by aquaporin 4 (AQP4) water channels. The pathway then directs flow towards the venous perivascular and perineuronal spaces, ultimately clearing solutes from the neuropil into meningeal and cervical lymphatic drainage vessels. In rodents, the glymphatic pathway is predominantly active during sleep, when the clearance of harmful metabolites such as amyloid β (Aβ) increases two-fold relative to the waking state. Glymphatic dysfunction, probably related to perturbed AQP4 expression, has been shown in animal models of traumatic brain injury, Alzheimer's disease, and stroke. The recent characterisations of the glymphatic and meningeal lymphatic systems in rodents and in humans call for revaluation of the anatomical routes for CSF-interstitial fluid flow and the physiological role that these pathways play in CNS health. RECENT DEVELOPMENTS Several features of the glymphatic and meningeal lymphatic systems have been shown to be present in humans. MRI scans with intrathecally administered contrast agent show that CSF flows along pathways that closely resemble the glymphatic system outlined in rodents. Furthermore, PET studies have revealed that Aβ accumulates in the healthy brain after a single night of sleep deprivation, suggesting that the human glymphatic pathway might also be primarily active during sleep. Other PET studies have shown that CSF clearance of Aβ and tau tracers is reduced in patients with Alzheimer's disease compared with healthy controls. The observed reduction in CSF clearance was associated with increasing grey-matter concentrations of Aβ in the human brain, consistent with findings in mice showing that decreased glymphatic function leads to Aβ accumulation. Altered AQP4 expression is also evident in brain tissue from patients with Alzheimer's disease or normal pressure hydrocephalus; glymphatic MRI scans of patients with normal pressure hydrocephalus show reduced CSF tracer entry and clearance. WHERE NEXT?: Research is needed to confirm whether specific factors driving glymphatic flow in rodents also apply to humans. Longitudinal imaging studies evaluating human CSF dynamics will determine whether a causal link exists between reduced brain solute clearance and the development of neurodegenerative diseases. Assessment of glymphatic function after stroke or traumatic brain injury could identify whether this function correlates with neurological recovery. New insights into how behaviour and genetics modify glymphatic function, and how this function decompensates in disease, should lead to the development of new preventive and diagnostic tools and novel therapeutic targets.
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Affiliation(s)
- Martin Kaag Rasmussen
- Centre for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Humberto Mestre
- Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, USA; Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, USA
| | - Maiken Nedergaard
- Centre for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, USA; Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, USA.
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147
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Bock HC, Dreha-Kulaczewski SF, Alaid A, Gärtner J, Ludwig HC. Upward movement of cerebrospinal fluid in obstructive hydrocephalus-revision of an old concept. Childs Nerv Syst 2019; 35:833-841. [PMID: 30919042 DOI: 10.1007/s00381-019-04119-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 03/08/2019] [Indexed: 12/26/2022]
Abstract
PURPOSE The specific pathophysiological processes in many forms of obstructive hydrocephalus (HC) are still unclear. Current concepts of cerebrospinal fluid (CSF) dynamics presume a constant downward flow from the lateral ventricles towards subarachnoid spaces, which are in contrast to neurosurgical observations and findings of MRI flow studies. The aim of our study was to analyze CSF movements in patients with obstructive HC by neuroendoscopic video recordings, X-ray studies, and MRI. METHODS One hundred seventeen pediatric patients with obstructive HC who underwent neuroendoscopy in our center were included. Video recordings were analyzed in 85 patients. Contrast-enhanced X-rays were conducted during surgery prior to intervention in 75 patients, and flow void signals on pre-operative MRI could be evaluated in 110 patients. RESULTS In 83.5% of the video recordings, CSF moved upwards synchronous to inspiration superimposed by cardiac pulsation. Application of contrast medium revealed a flow delay in 52% of the X-ray studies prior to neurosurgery, indicating hindered CSF circulation. The appearances and shapes of flow void signals in 88.2% of the pre-operative MRI studies suggested valve-like mechanisms and entrapment of CSF. CONCLUSIONS Neuroendoscopic observations in patients with obstructive HC revealed upward CSF movements and the corresponding MRI signs of trapped CSF in brain cavities. These observations are in contrast to the current pathophysiological concept of obstructive HC. However, recent real-time flow MRI studies demonstrated upward movement of CSF, hence support our clinical findings. The knowledge of cranial-directed CSF flow expands our understanding of pathophysiological mechanisms in HC and is the key to effective treatment.
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Affiliation(s)
- Hans C Bock
- Department of Neurosurgery, Section Pediatric Neurosurgery, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Steffi F Dreha-Kulaczewski
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Neurology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Awad Alaid
- Department of Neurosurgery, Section Pediatric Neurosurgery, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Jutta Gärtner
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Neurology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Hans C Ludwig
- Department of Neurosurgery, Section Pediatric Neurosurgery, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany.
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148
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Sakhare AR, Barisano G, Pa J. Assessing test-retest reliability of phase contrast MRI for measuring cerebrospinal fluid and cerebral blood flow dynamics. Magn Reson Med 2019; 82:658-670. [PMID: 31020721 DOI: 10.1002/mrm.27752] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 02/06/2023]
Abstract
PURPOSE Pathological states occur when cerebrospinal fluid (CSF) and cerebral blood flow (CBF) dynamics become dysregulated in the brain. Phase-contrast MRI (PC-MRI) is a noninvasive imaging technique that enables quantitative measurements of CSF and CBF flow. While studies have validated PC-MRI as an imaging technique for flow, few studies have evaluated its reliability for CSF and CBF flow parameters commonly associated with neurological disease. The purpose of this study was to evaluate test-retest reliability at the cerebral aqueduct (CA) and C2-C3 area using PC-MRI to assess the feasibility of investigating CSF and CBF flow dynamics. METHODS This study was performed on 27 cognitively normal young adults (ages 20-35 years). Flow data was acquired on a 3T Siemens Prisma using a 2D cine-PC pulse sequence. Three consecutive flow measurements were acquired at the CA and C2-C3 area. Intraclass correlation coefficient (ICC) and coefficient of variance (CV) were used to evaluate intrarater, inter-rater, and test-retest reliability. RESULTS Among the 26 flow parameters analyzed, 22 had excellent reliability (ICC > 0.80), including measurements of CSF stroke volume, flush peak, and fill peak, and 4 parameters had good reliability (ICC 0.60-0.79). 16 flow parameters had a mean CV ≤ 10%, 7 had a CV ≤ 15%, and 3 had a CV ≤ 30%. All CSF and CBF flow measurements had excellent inter-rater and intrarater reliability (ICC > 0.80). CONCLUSION This study shows that CSF and CBF flow can be reliably measured at the CA and C2-C3 area using PC-MRI, making it a promising tool for studying flow dynamics in the central nervous system.
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Affiliation(s)
- Ashwin R Sakhare
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California.,Department of Neurology, Laboratory of Neuro Imaging, Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, California
| | - Giuseppe Barisano
- Department of Neurology, Laboratory of Neuro Imaging, Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, California.,Neuroscience Graduate Program, University of Southern California, Los Angeles, California
| | - Judy Pa
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California.,Department of Neurology, Laboratory of Neuro Imaging, Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, California.,Neuroscience Graduate Program, University of Southern California, Los Angeles, California
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149
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Nuckowska MK, Gruszecki M, Kot J, Wolf J, Guminski W, Frydrychowski AF, Wtorek J, Narkiewicz K, Winklewski PJ. Impact of slow breathing on the blood pressure and subarachnoid space width oscillations in humans. Sci Rep 2019; 9:6232. [PMID: 30996273 PMCID: PMC6470142 DOI: 10.1038/s41598-019-42552-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/29/2019] [Indexed: 02/08/2023] Open
Abstract
The aim of the study was to assess cardiac and respiratory blood pressure (BP) and subarachnoid space (SAS) width oscillations during the resting state for slow and fast breathing and breathing against inspiratory resistance. Experiments were performed on a group of 20 healthy volunteers (8 males and 12 females; age 25.3 ± 7.9 years; BMI = 22.1 ± 3.2 kg/m2). BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography. SAS signals were recorded using an SAS monitor. Oxyhaemoglobin saturation (SaO2) and end-tidal CO2 (EtCO2) were measured using a medical monitoring system. Procedure 1 consisted of breathing spontaneously and at controlled rates of 6 breaths/minute and 6 breaths/minute with inspiratory resistance for 10 minutes. Procedure 2 consisted of breathing spontaneously and at controlled rates of 6, 12 and 18 breaths/minute for 5 minutes. Wavelet analysis with the Morlet mother wavelet was applied for delineation of BP and SAS signals cardiac and respiratory components. Slow breathing diminishes amplitude of cardiac BP and SAS oscillations. The overall increase in BP and SAS oscillations during slow breathing is driven by the respiratory component. Drop in cardiac component of BP amplitude evoked by slow-breathing may be perceived as a cardiovascular protective mechanism to avoid target organ damage. Further studies are warranted to assess long-term effects of slow breathing.
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Affiliation(s)
- Magdalena K Nuckowska
- Department of Human Physiology, Faculty of Health Sciences, Medical University of Gdansk, Gdansk, Poland
| | - Marcin Gruszecki
- Department of Radiology Informatics and Statistics, Faculty of Health Sciences, Medical University of Gdansk, Gdansk, Poland
| | - Jacek Kot
- National Centre for Hyperbaric Medicine, Institute of Maritime and Tropical Medicine, Faculty of Health Sciences, Medical University of Gdansk, Gdynia, Poland
| | - Jacek Wolf
- Department of Hypertension and Diabetology, Faculty of Medicine, Medical University of Gdansk, Gdansk, Poland
| | - Wojciech Guminski
- Department of Computer Communications, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, Gdansk, Poland
| | | | - Jerzy Wtorek
- Department of Biomedical Engineering, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, Gdansk, Poland
| | - Krzysztof Narkiewicz
- Department of Hypertension and Diabetology, Faculty of Medicine, Medical University of Gdansk, Gdansk, Poland
| | - Pawel J Winklewski
- Department of Human Physiology, Faculty of Health Sciences, Medical University of Gdansk, Gdansk, Poland.
- Department of Clinical Anatomy and Physiology, Faculty of Health Sciences, Pomeranian University of Slupsk, Slupsk, Poland.
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150
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Boschert AL, Elmenhorst D, Gauger P, Li Z, Garcia-Gutierrez MT, Gerlach D, Johannes B, Zange J, Bauer A, Rittweger J. Sleep Is Compromised in -12° Head Down Tilt Position. Front Physiol 2019; 10:397. [PMID: 31040791 PMCID: PMC6477049 DOI: 10.3389/fphys.2019.00397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 03/21/2019] [Indexed: 11/23/2022] Open
Abstract
Recent studies are elucidating the interrelation between sleep, cranial perfusion, and cerebrospinal fluid (CSF) circulation. Head down tilt (HDT) as a simulation of microgravity reduces cranial perfusion. Therefore, our aim was to assess whether HDT is affecting sleep (clinicaltrials.gov; identifier NCT 02976168). 11 male subjects were recruited for a cross-over designed study. Each subject participated in two campaigns each comprising 3 days and 2 nights. Intervention started on the second campaign day and consisted of maintenance of horizontal position or −12° HDT for 21 h. Ultrasound measurements were performed before, at the beginning and the end of intervention. Polysomnographic measurements were assessed in the second night which was either spent in horizontal posture or at −12° HDT. Endpoints were sleep efficiency, sleep onset latency, number of sleep state changes and arousals, percentages of N3, REM, light sleep stages and subjective sleep parameters. N3 and REM sleep reduced by 25.6 and 19.1 min, respectively (P = 0.002, g = -0.898; P = 0.035, g = -0.634) during −12° HDT. Light sleep (N1/2) increased by 33.0 min at −12° HDT (P = 0.002, g = 1.078). On a scale from 1 to 9 subjective sleep quality deteriorated by 1.3 points during −12° HDT (P = 0.047, g = -0.968). Ultrasonic measurement of the venous system showed a significant increase of the minimum (P = 0.009, P < 0.001) and maximum (P = 0.004, P = 0.002) cross-sectional area of the internal jugular vein at −12° HDT. The minimum cross-sectional area of the external jugular vein differed significantly between conditions over time (P = 0.001) whereas frontal skin tissue thickness was not significantly different between conditions (P = 0.077, P = 0.811). Data suggests venous congestion at −12° HDT. Since subjects felt comfortable with lying in −12° HDT under our experimental conditions, this posture only moderately deteriorates sleep. Obviously, the human body can almost compensate the several fold effects of gravity in HDT posture like an affected CSF circulation, airway obstruction, unusual patterns of propioception and effects on the cardiovascular system.
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Affiliation(s)
- Alessa L Boschert
- Department of Muscle and Bone Metabolism, German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - David Elmenhorst
- Forschungszentrum Jülich, Institute of Neuroscience and Medicine (INM-2), Jülich, Germany.,Division of Medical Psychology, University of Bonn, Bonn, Germany
| | - Peter Gauger
- Department of Muscle and Bone Metabolism, German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Zhili Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | | | - Darius Gerlach
- Department of Muscle and Bone Metabolism, German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Bernd Johannes
- Department of Muscle and Bone Metabolism, German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Jochen Zange
- Department of Muscle and Bone Metabolism, German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Andreas Bauer
- Forschungszentrum Jülich, Institute of Neuroscience and Medicine (INM-2), Jülich, Germany.,Neurological Department, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Jörn Rittweger
- Department of Muscle and Bone Metabolism, German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany.,Department of Pediatrics and Adolescent Medicine, University of Cologne, Cologne, Germany
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