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Podgoršak A, Flürenbrock F, Trimmel NE, Korn L, Oertel MF, Stieglitz L, Fernandes Dias S, Hierweger MM, Zeilinger M, Weisskopf M, Schmid Daners M. Toward the "Perfect" Shunt: Historical Vignette, Current Efforts, and Future Directions. Adv Tech Stand Neurosurg 2024; 50:1-30. [PMID: 38592526 DOI: 10.1007/978-3-031-53578-9_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
As a concept, drainage of excess fluid volume in the cranium has been around for more than 1000 years. Starting with the original decompression-trepanation of Abulcasis to modern programmable shunt systems, to other nonshunt-based treatments such as endoscopic third ventriculostomy and choroid plexus cauterization, we have come far as a field. However, there are still fundamental limitations that shunts have yet to overcome: namely posture-induced over- and underdrainage, the continual need for valve opening pressure especially in pediatric cases, and the failure to reinstall physiologic intracranial pressure dynamics. However, there are groups worldwide, in the clinic, in industry, and in academia, that are trying to ameliorate the current state of the technology within hydrocephalus treatment. This chapter aims to provide a historical overview of hydrocephalus, current challenges in shunt design, what members of the community have done and continue to do to address these challenges, and finally, a definition of the "perfect" shunt is provided and how the authors are working toward it.
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Affiliation(s)
- Anthony Podgoršak
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Fabian Flürenbrock
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Nina Eva Trimmel
- Center for Preclinical Development, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Leonie Korn
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Markus Florian Oertel
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Lennart Stieglitz
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sandra Fernandes Dias
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Melanie Michaela Hierweger
- Center for Preclinical Development, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Melanie Zeilinger
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Miriam Weisskopf
- Center for Preclinical Development, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Marianne Schmid Daners
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
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Qvarlander S, Dombrowski SM, Biswas D, Thyagaraj S, Loth F, Yang J, Luciano MG. Modifying the ICP pulse wave: effects on parenchymal blood flow pulsatility. J Appl Physiol (1985) 2023; 134:242-252. [PMID: 36548513 PMCID: PMC9886344 DOI: 10.1152/japplphysiol.00401.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 12/07/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Pulsation of the cerebral blood flow (CBF) produces intercranial pressure (ICP) waves. The aim of this study is to determine whether externally modifying ICP pulsatility alters parenchymal blood flow pulsatility. A cardiac-gated inflatable device was inserted in the lateral epidural space of 12 anesthetized canines (canis familiaris) and used to cause reduction, inversion, and augmentation of the ICP pulse. CBF in each hemisphere was measured using laser Doppler velocimetry. A significant increase in both mean CBF and its amplitude was observed for reduction as well as inversion of the ICP pulse, with larger changes observed for the inversion protocol. Significant increases in the mean CBF were also observed ipsilaterally for the augmentation protocol together with indications of reduced CBF amplitude contralaterally. External alteration of the ICP pulse thus caused significant changes in parenchymal blood flow pulsatility. The inverse relationship between the ICP and CBF amplitude suggests that the changes did not occur via modification of the intracranial Windkessel mechanism. Thus, the effects likely occurred in the low-pressure vessels, i.e., capillaries and/or venules, rather than the high-pressure arteries. Future MRI studies are however required to map and quantify the effects on global cerebral blood flow.NEW & NOTEWORTHY This study demonstrated that external modification of ICP pulsatility, using a cardiac-gated inflatable device implanted epidurally in canines, alters brain tissue blood flow pulsatility. Specifically, decreasing systolic ICP increased blood flow pulsatility in brain tissue. The results suggest that the altered CBF pulsatility is unlikely to depend on modification of the Windkessel effect on the feeding arterial system but was rather an effect directly on tissue and the lower pressure distal vessels.
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Affiliation(s)
- Sara Qvarlander
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, Umeå, Sweden
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland, Ohio
| | | | - Dipankar Biswas
- Department of Neurosurgery, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Suraj Thyagaraj
- Department of Biomedical Engineering, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Francis Loth
- Department of Mechanical and Industrial Engineering and Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Jun Yang
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland, Ohio
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, People's Republic of China
| | - Mark G Luciano
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland, Ohio
- Department of Neurosurgery, Johns Hopkins Medical Institutions, Baltimore, Maryland
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3
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Doron O, Zadka Y, Rosenthal G, Barnea O. Intracranial Pulsating Balloon-Based Cardiac-Gated ICP Modulation Impact on Brain Oxygenation: A Proof-of-Concept Study in a Swine Model. Neurocrit Care 2022; 37:689-696. [PMID: 35854081 DOI: 10.1007/s12028-022-01541-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 05/25/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND Brain oxygenation improvement is a sought-after goal in neurocritical care patients. Previously, we have shown that cerebral blood flow improvement by cardiac-gated intracranial pressure (ICP) modulation using an intracranial pulsating balloon is feasible in a swine model. We sought to explore specific ICP modulation protocols to assess the feasibility of influencing brain oxygenation. METHODS A previously presented electrocardiogram (ECG)-gated intracranial balloon pump in which volume, timing, and duty cycle of balloon inflation could be altered was used. Different protocols were tested in a swine model of normal and elevated ICP attained by intracranial fluid infusion with continuous monitoring of physiological parameters, and brain tissue oxygen tension (PbtO2) was measured at baseline and after device activation. RESULTS We studied five swine, subjected to two main protocols differing in their phase relative to the cardiac cycle. In reduced brain perfusion status (ICP > 20 mm Hg, PbtO2 < 15 mm Hg), the late-diastolic-early-systolic (Inflation/deflation) protocol showed consistent elevation in PbtO2 (+ 9%, p < 0.01), coupled with ICP reduction (- 12%, p < 0.01), whereas the early-systolic-late-diastolic (inflation/deflation) protocol resulted in PbtO2 reduction (- 4%, p < 0.01), coupled with ICP increase (+ 5% above baseline, p < 0.01). No significant changes in brain oxygenation or ICP were observed at normal perfusion status (ICP < 20 mm Hg, PbtO2 > 15 mm Hg). CONCLUSIONS Intracranial cardiac-gated balloon pump activation can influence cerebral oxygenation and raise PbtO2 above threshold values. This study supports the concept of late-diastolic pressure rise, coupled with early-systolic pressure drop, as a potential effector of flow augmentation leading to improve brain tissue oxygenation. Further studies are warranted to assess the translational potential of using an intracranial cardiac-gated balloon pump device to improve brain tissue oxygenation.
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Affiliation(s)
- Omer Doron
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel. .,Department of Neurosurgery, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lenox Hill Hospital, 130 77th street, New York, NY, USA.
| | - Yuliya Zadka
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Guy Rosenthal
- Department of Neurosurgery, Hadassah University Medical Center, Jerusalem, Israel
| | - Ofer Barnea
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
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4
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Li J, Zhang X, Guo J, Yu C, Yang J. Molecular Mechanisms and Risk Factors for the Pathogenesis of Hydrocephalus. Front Genet 2022; 12:777926. [PMID: 35047005 PMCID: PMC8762052 DOI: 10.3389/fgene.2021.777926] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 12/03/2021] [Indexed: 12/22/2022] Open
Abstract
Hydrocephalus is a neurological condition due to the aberrant circulation and/or obstruction of cerebrospinal fluid (CSF) flow with consequent enlargement of cerebral ventricular cavities. However, it is noticed that a lot of patients may still go through symptomatic progression despite standard shunting procedures, suggesting that hydrocephalus is far more complicated than a simple CSF circulative/obstructive disorder. Growing evidence indicates that genetic factors play a fundamental role in the pathogenesis of some hydrocephalus. Although the genetic research of hydrocephalus in humans is limited, many genetic loci of hydrocephalus have been defined in animal models. In general, the molecular abnormalities involved in the pathogenesis of hydrocephalus include brain development and ependymal cell dysfunction, apoptosis, inflammation, free radical generation, blood flow, and cerebral metabolism. Moreover, recent studies have indicated that the molecular abnormalities relevant to aberrant cerebral glymphatic drainage turn into an attractive subject in the CSF circulation disorder. Furthermore, the prevalent risk factors could facilitate the development of hydrocephalus. In this review, we elicited some possible fundamental molecular mechanisms and facilitating risk factors involved in the pathogenesis of hydrocephalus, and aimed to widen the diagnosis and therapeutic strategies for hydrocephalus management. Such knowledge could be used to improve patient care in different ways, such as early precise diagnosis and effective therapeutic regimens.
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Affiliation(s)
- Jingwen Li
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Xinjie Zhang
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin, China
| | - Jian Guo
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Chen Yu
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Jun Yang
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
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McAllister JP, Talcott MR, Isaacs AM, Zwick SH, Garcia-Bonilla M, Castaneyra-Ruiz L, Hartman AL, Dilger RN, Fleming SA, Golden RK, Morales DM, Harris CA, Limbrick DD. A novel model of acquired hydrocephalus for evaluation of neurosurgical treatments. Fluids Barriers CNS 2021; 18:49. [PMID: 34749745 PMCID: PMC8576945 DOI: 10.1186/s12987-021-00281-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 10/09/2021] [Indexed: 02/07/2023] Open
Abstract
Background Many animal models have been used to study the pathophysiology of hydrocephalus; most of these have been rodent models whose lissencephalic cerebral cortex may not respond to ventriculomegaly in the same way as gyrencephalic species and whose size is not amenable to evaluation of clinically relevant neurosurgical treatments. Fewer models of hydrocephalus in gyrencephalic species have been used; thus, we have expanded upon a porcine model of hydrocephalus in juvenile pigs and used it to explore surgical treatment methods. Methods Acquired hydrocephalus was induced in 33–41-day old pigs by percutaneous intracisternal injections of kaolin (n = 17). Controls consisted of sham saline-injected (n = 6) and intact (n = 4) animals. Magnetic resonance imaging (MRI) was employed to evaluate ventriculomegaly at 11–42 days post-kaolin and to plan the surgical implantation of ventriculoperitoneal shunts at 14–38-days post-kaolin. Behavioral and neurological status were assessed. Results Bilateral ventriculomegaly occurred post-induction in all regions of the cerebral ventricles, with prominent CSF flow voids in the third ventricle, foramina of Monro, and cerebral aqueduct. Kaolin deposits formed a solid cast in the basal cisterns but the cisterna magna was patent. In 17 untreated hydrocephalic animals. Mean total ventricular volume was 8898 ± 5917 SD mm3 at 11–43 days of age, which was significantly larger than the baseline values of 2251 ± 194 SD mm3 for 6 sham controls aged 45–55 days, (p < 0.001). Past the post-induction recovery period, untreated pigs were asymptomatic despite exhibiting mild-moderate ventriculomegaly. Three out of 4 shunted animals showed a reduction in ventricular volume after 20–30 days of treatment, however some developed ataxia and lethargy, from putative shunt malfunction. Conclusions Kaolin induction of acquired hydrocephalus in juvenile pigs produced an in vivo model that is highly translational, allowing systematic studies of the pathophysiology and clinical treatment of hydrocephalus. Supplementary Information The online version contains supplementary material available at 10.1186/s12987-021-00281-0.
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Affiliation(s)
- James P McAllister
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA. .,Department of Neurosurgery, BJC Institute of Health, 425 S. Euclid, Campus, Box 8057, St. Louis, MO, 63143, USA.
| | - Michael R Talcott
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA.,Division of Comparative Medicine, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA
| | - Albert M Isaacs
- Department of Surgery, Division of Neurosurgery, University of Calgary School of Medicine, Calgary, AB, T2N 2T9, Canada
| | - Sarah H Zwick
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA
| | - Maria Garcia-Bonilla
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA
| | - Leandro Castaneyra-Ruiz
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA
| | - Alexis L Hartman
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA
| | - Ryan N Dilger
- Department of Animal Sciences, Division of Nutritional Sciences, Neuroscience Program, University of Illinois, Champagne-Urbana, Illinois, 61801, USA.,Traverse Science, Champaign, IL, 61801, USA
| | - Stephen A Fleming
- Department of Animal Sciences, Division of Nutritional Sciences, Neuroscience Program, University of Illinois, Champagne-Urbana, Illinois, 61801, USA.,Traverse Science, Champaign, IL, 61801, USA
| | - Rebecca K Golden
- Department of Animal Sciences, Division of Nutritional Sciences, Neuroscience Program, University of Illinois, Champagne-Urbana, Illinois, 61801, USA
| | - Diego M Morales
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA
| | - Carolyn A Harris
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, MI, 48202 , USA.,Department of Neurosurgery, Wayne State University School of Medicine, Detroit, MI, 48202, USA
| | - David D Limbrick
- Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA.,Department of Pediatrics, St. Louis Children's Hospital, St. Louis, MO, 63110, USA
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6
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Zhang B, Huang Z, Song H, Kim HS, Park J. Wearable Intracranial Pressure Monitoring Sensor for Infants. BIOSENSORS 2021; 11:213. [PMID: 34210050 PMCID: PMC8301997 DOI: 10.3390/bios11070213] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/26/2021] [Accepted: 06/28/2021] [Indexed: 11/22/2022]
Abstract
Monitoring of intracranial pressure (ICP) is important for patients at risk of raised ICP, which may indicate developing diseases in brains that can lead to brain damage or even death. Monitoring ICP can be invaluable in the management of patients suffering from brain injury or hydrocephalus. To date, invasive measurements are still the standard method for monitoring ICP; however, these methods can not only cause bleeding or infection but are also very inconvenient to use, particularly for infants. Currently, none of the non-invasive methods can provide sufficient accuracy and ease of use while allowing continuous monitoring in routine clinical use at low cost. Here, we have developed a wearable, non-invasive ICP sensor that can be used like a band-aid. For the fabrication of the ICP sensor, a novel freeze casting method was developed to encapsulate the liquid metal microstructures within thin and flexible polymers. The final thickness of the ICP sensor demonstrated is 500 µm and can be further reduced. Three different designs of ICP sensors were tested under various pressure actuation conditions as well as different temperature environments, where the measured pressure changes were stable with the largest stability coefficient of variation being only CV = 0.0206. In addition, the sensor output values showed an extremely high linear correlation (R2 > 0.9990) with the applied pressures.
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Affiliation(s)
- Baoyue Zhang
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China; (B.Z.); (Z.H.); (H.S.)
| | - Ziyi Huang
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China; (B.Z.); (Z.H.); (H.S.)
| | - Huixue Song
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China; (B.Z.); (Z.H.); (H.S.)
| | - Hyun Soo Kim
- Department of Electronic Engineering, Kwangwoon University, Seoul 01897, Korea
| | - Jaewon Park
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China; (B.Z.); (Z.H.); (H.S.)
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Gallina P, Nicoletti C, Scollato A, Lolli F. The "Glymphatic-Lymphatic System Pathology" and a New Categorization of Neurodegenerative Disorders. Front Neurosci 2021; 15:669681. [PMID: 34093117 PMCID: PMC8172792 DOI: 10.3389/fnins.2021.669681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/14/2021] [Indexed: 12/20/2022] Open
Affiliation(s)
- Pasquale Gallina
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy.,Neurosurgical Unit, Careggi University Hospital, Florence, Italy
| | - Claudio Nicoletti
- Department of Experimental and Clinical Medicine, Section of Anatomy, University of Florence, Florence, Italy
| | | | - Francesco Lolli
- Department of Clinical and Experimental Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
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8
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Luciano MG, Dombrowski SM, El-Khoury S, Yang J, Thyagaraj S, Qvarlander S, Khalid S, Suk I, Manbachi A, Loth F. Epidural Oscillating Cardiac-Gated Intracranial Implant Modulates Cerebral Blood Flow. Neurosurgery 2020; 87:1299-1310. [PMID: 32533835 PMCID: PMC7666905 DOI: 10.1093/neuros/nyaa188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 03/16/2020] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND We have previously reported a method and device capable of manipulating ICP pulsatility while minimally effecting mean ICP. OBJECTIVE To test the hypothesis that different modulations of the intracranial pressure (ICP) pulse waveform will have a differential effect on cerebral blood flow (CBF). METHODS Using an epidural balloon catheter attached to a cardiac-gated oscillating pump, 13 canine subjects underwent ICP waveform manipulation comparing different sequences of oscillation in successive animals. The epidural balloon was implanted unilaterally superior to the Sylvian sulcus. Subjects underwent ICP pulse augmentation, reduction and inversion protocols, directly comparing time segments of system activation and deactivation. ICP and CBF were measured bilaterally along with systemic pressure and heart rate. CBF was measured using both thermal diffusion, and laser doppler probes. RESULTS The activation of the cardiac-gate balloon implant resulted in an ipsilateral/contralateral ICP pulse amplitude increase with augmentation (217%/202% respectively, P < .0005) and inversion (139%/120%, P < .0005). The observed changes associated with the ICP mean values were smaller, increasing with augmentation (23%/31%, P < .0001) while decreasing with inversion (7%/11%, P = .006/.0003) and reduction (4%/5%, P < .0005). CBF increase was observed for both inversion and reduction protocols (28%/7.4%, P < .0001/P = .006 and 2.4%/1.3%, P < .0001/P = .003), but not the augmentation protocol. The change in CBF was correlated with ICP pulse amplitude and systolic peak changes and not with change in mean ICP or systemic variables (heart rate, arterial blood pressure). CONCLUSION Cardiac-gated manipulation of ICP pulsatility allows the study of intracranial pulsatile dynamics and provides a potential means of altering CBF.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Amir Manbachi
- Correspondence: Mark G. Luciano, MD, PhD, Departments of Neurosurgery and Biomedical Engineering, Johns Hopkins University, 600 North Wolfe Street, Phipps 126, Baltimore, MD 20287, USA.
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9
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Doron O, Or T, Battino L, Rosenthal G, Barnea O. Cerebral blood flow augmentation using a cardiac-gated intracranial pulsating balloon pump in a swine model of elevated ICP. J Neurosurg 2020; 132:1606-1615. [PMID: 30978692 DOI: 10.3171/2019.1.jns182864] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/03/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Augmenting brain perfusion or reducing intracranial pressure (ICP) dose is the end target of many therapies in the neuro-critical care unit. Many present therapies rely on aggressive systemic interventions that may lead to untoward effects. Previous studies have used a cardiac-gated intracranial balloon pump (ICBP) to model hydrocephalus or to flatten the ICP waveform. The authors sought to sought to optimize ICBP activation parameters to improve cerebral physiological parameters in a swine model of raised ICP. METHODS The authors developed a cardiac-gated ICBP in which the volume, timing, and duty cycle (time relative to a single cardiac cycle) of balloon inflation could be altered. They studied the ICBP in a swine model of elevated ICP attained by continuous intracranial fluid infusion with continuous monitoring of systemic and cerebral physiological parameters, and defined two specific protocols of ICBP activation. RESULTS Eleven swine were studied, 3 of which were studied to define the optimal timing, volume, and duty cycle of balloon inflation. Eight swine were studied with two defined protocols at baseline and with ICP gradually raised to a mean of 30.5 mm Hg. ICBP activation caused a consistent modification of the ICP waveform. Two ICBP activation protocols were used. Balloon activation protocol A led to a consistent elevation in cerebral blood flow (8%-25% above baseline, p < 0.00001). Protocol B resulted in a modest reduction of ICP over time (8%-11%, p < 0.0001) at all ICP levels. Neither protocol significantly affected systemic physiological parameters. CONCLUSIONS The preliminary results indicate that optimized protocols of ICBP activation may have beneficial effects on cerebral physiological parameters, with minimal effect on systemic parameters. Further studies are warranted to explore whether ICBP protocols may be of clinical benefit in patients with brain injuries with increased ICP.
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Affiliation(s)
- Omer Doron
- 1Department of Neurosurgery, Hadassah-Hebrew University Medical Center, Jerusalem; and
- 2Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Tal Or
- 2Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Limor Battino
- 2Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Guy Rosenthal
- 1Department of Neurosurgery, Hadassah-Hebrew University Medical Center, Jerusalem; and
| | - Ofer Barnea
- 2Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
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10
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Khani M, Sass LR, Xing T, Keith Sharp M, Balédent O, Martin BA. Anthropomorphic Model of Intrathecal Cerebrospinal Fluid Dynamics Within the Spinal Subarachnoid Space: Spinal Cord Nerve Roots Increase Steady-Streaming. J Biomech Eng 2019; 140:2683234. [PMID: 30003260 DOI: 10.1115/1.4040401] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Indexed: 11/08/2022]
Abstract
Cerebrospinal fluid (CSF) dynamics are thought to play a vital role in central nervous system (CNS) physiology. The objective of this study was to investigate the impact of spinal cord (SC) nerve roots (NR) on CSF dynamics. A subject-specific computational fluid dynamics (CFD) model of the complete spinal subarachnoid space (SSS) with and without anatomically realistic NR and nonuniform moving dura wall deformation was constructed. This CFD model allowed detailed investigation of the impact of NR on CSF velocities that is not possible in vivo using magnetic resonance imaging (MRI) or other noninvasive imaging methods. Results showed that NR altered CSF dynamics in terms of velocity field, steady-streaming, and vortical structures. Vortices occurred in the cervical spine around NR during CSF flow reversal. The magnitude of steady-streaming CSF flow increased with NR, in particular within the cervical spine. This increase was located axially upstream and downstream of NR due to the interface of adjacent vortices that formed around NR.
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Affiliation(s)
- Mohammadreza Khani
- Neurophysiological Imaging and Modeling Laboratory, Department of Biological Engineering, University of Idaho, Moscow, ID 83844 e-mail:
| | - Lucas R Sass
- Neurophysiological Imaging and Modeling Laboratory, Department of Biological Engineering, University of Idaho, Moscow, ID 83844 e-mail:
| | - Tao Xing
- Department of Mechanical Engineering, University of Idaho, Moscow, ID 83844 e-mail:
| | - M Keith Sharp
- Biofluid Mechanics Laboratory, University of Louisville, Louisville, KY 40292 e-mail:
| | - Olivier Balédent
- Bioflow Image, CHU Nord Amiens-Picardie, Amiens 80054, France e-mail:
| | - Bryn A Martin
- Neurophysiological Imaging and Modeling Laboratory, Department of Biological Engineering, University of Idaho, Moscow, ID 83844 e-mail:
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11
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Subdural effusion protects the aging brain from harmful ventriculomegaly. Med Hypotheses 2017; 108:108-114. [PMID: 29055382 DOI: 10.1016/j.mehy.2017.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/17/2017] [Accepted: 08/06/2017] [Indexed: 11/21/2022]
Abstract
The human brain loses its volume and its function during aging. The solid part of the brain within the intracranial space, the brain parenchyma, decreases in volume with age; while the cerebrospinal fluid (CSF) volume increases. With progressive loss of brain parenchymal volume (BPV), CSF may shift from cerebral ventricles to the subdural space, forming subdural effusion (SDE), whose role in the brain aging process remains unclear. We hypothesize that damages associated with ventriculomegaly can be lessened after formation of SDE. As the BPV decreases, the enlarged ventricular surface area causes dysfunction of its lining ependymal cells, followed by damages to the periventricular tissue. The periventricular nerve fibers are stretched by the enlarged ventricles. We hypothesize that after the formation of SDE, ventriculomegaly can be stopped or even reversed. By allowing the atrophic brain to reside in a smaller fraction of the intracranial volume, damages associated with ventriculomegaly can be alleviated. If our hypothesis is correct, physicians should continue to maintain a conservative approach for uncomplicated SDE. For focal or global brain parenchymal loss caused by various pathologies, intracranial spacers can be employed to simulate the effect of SDE to protect the brain. For treatment of idiopathic normal pressure hydrocephalus, aggressive ventricular size reduction should be pursued. Finally, the protective effects of SDE have its limits. Extremely enlarged subdural volume can cause acute or chronic subdural hematoma, further damaging the brain.
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