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Owashi KP, Capel C, Balédent O. Cerebral arterial flow dynamics during systole and diastole phases in young and older healthy adults. Fluids Barriers CNS 2023; 20:65. [PMID: 37705096 PMCID: PMC10500860 DOI: 10.1186/s12987-023-00467-8] [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: 03/12/2023] [Accepted: 09/05/2023] [Indexed: 09/15/2023] Open
Abstract
BACKGROUND Since arterial flow is the leading actor in neuro-fluids flow dynamics, it might be interesting to assess whether it is meaningful to study the arterial flow waveform in more detail and whether this provides new important information. Few studies have focused on determining the influence of heart rate variation over time on the arterial flow curve. Therefore, this study aimed to evaluate cerebral arterial flow waveforms at extracranial and intracranial compartments in young and elderly healthy adults, also considering systole and diastole phases. METHODS Cine phase-contrast magnetic resonance imaging (CINE-PC MRI) was performed on twenty-eight healthy young volunteers (HYV) and twenty healthy elderly volunteers (HEV) to measure arterial blood flows at the extracranial and intracranial planes. A semi-automated protocol using MATLAB scripts was implemented to identify the main representative points in the arterial flow waveforms. Representative arterial profiles were estimated for each group. Moreover, the effects of age and sex on flow times, amplitude-related parameters, and parameters related to systole and diastole phases were evaluated at the extracranial and intracranial compartments. Student's t-test or Wilcoxon's test (depending on the normality of the distribution) was used to detect significant differences. RESULTS In HYVs, significant differences were observed between extracranial and intracranial levels in parameters related to the AP1 amplitude. Besides the detected differences in pulsatility index (extracranial: 0.92 ± 0.20 vs. 1.28 ± 0.33; intracranial: 0.79 ± 0.15 vs. 1.14 ± 0.18, p < .001) and average flow (715 ± 136 vs. 607 ± 125 ml/min, p = .008) between HYV and HEV, differences in the amplitude value of the arterial flow profile feature points were also noted. Contrary to systole duration (HYV: 360 ± 29 ms; HEV: 364 ± 47 ms), diastole duration presented higher inter-individual variability in both populations (HYV: 472 ± 145 ms; HEV: 456 ± 106 ms). Our results also showed that, with age, it is mainly the diastolic phase that changes. Although no significant differences in duration were observed between the two populations, the mean flow value in the diastolic phase was significantly lower in HEV (extracranial: 628 ± 128 vs. 457 ± 111 ml/min; intracranial: 599 ± 121 vs. 473 ± 100 ml/min, p < .001). No significant differences were observed in the arterial flow parameters evaluated between females and males in either HYV or HEV. CONCLUSION Our study provides a novel contribution on the influence of the cardiac cycle phases on cerebral arterial flow. The main contribution in this study concerns the identification of age-related alterations in cerebral blood flow, which occur mainly during the diastolic phase. Specifically, we observed that mean flow significantly decreases with age during diastole, whereas mean flow during systole is consistent.
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Affiliation(s)
| | - Cyrille Capel
- CHIMERE UR 7516, Jules Verne University of Picardy, Amiens, France
- Neurosurgery Department, Amiens Picardy University Medical Center, Amiens, France
| | - Olivier Balédent
- CHIMERE UR 7516, Jules Verne University of Picardy, Amiens, France
- Medical Image Processing Department, Amiens Picardy University Medical Center, Amiens, France
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Thibeault CM, Dorn AY, Radhakrishnan S, Hamilton RB. Longitudinal assessment of hemodynamic alterations after mild traumatic brain injury in adolescents: Selected case study review. JOURNAL OF CONCUSSION 2022. [DOI: 10.1177/20597002211065855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Alterations in the neurovasculature after traumatic brain injury (TBI) represents a significant sequelae. However, despite theoretical and empirical evidence supporting the near-ubiquity of vascular injury, its pathophysiology remains elusive. Although this has been shown for all grades of TBI, the vascular changes after injuries with the broad mild traumatic brain injuries (mTBI) classification, remain particularly difficult to describe. Our group has previously demonstrated hemodynamic alterations in mTBI by utilizing transcranial Doppler ultrasound and cerebrovascular reactivity in a cross-sectional study. That work identified a phasic progression of deviations over varying days post-injury. These phases were then characterized by a set of inverse models that provided a hypothetical process of hemodynamic dysfunction after mTBI. This model set provides a framework with the potential for guiding clinical treatment over the course of recovery. However, it is still unclear if individual patients will progress through the phases of dysfunction similar to that found at the population level. The work presented here explores six individual patients with high-density data collected during their post-injury recovery. Breath-hold index (BHI) was found to be the most robust feature related to mTBI longitudinally. All six subjects exhibited BHI recovery curves that followed the population model's progression. The changes in pulsatile features lacked the universality of BHI, but were present in subjects with higher self-reported symptom scores and longer periods of recovery. This work suggests neurovascular dysfunction after an mTBI may be a robust phenomenon. Additionally, the capabilities of TCD in capturing these changes highlights its potential for aiding clinicians in monitoring patient's recovery post mTBI.
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3
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Dias SF, Jehli E, Haas-Lude K, Bevot A, Okechi H, Zipfel J, Schuhmann MU. Ventriculomegaly in children: nocturnal ICP dynamics identify pressure-compensated but active paediatric hydrocephalus. Childs Nerv Syst 2021; 37:1883-1893. [PMID: 33884480 DOI: 10.1007/s00381-021-05164-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 04/12/2021] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Paediatric ventriculomegaly without obvious signs or symptoms of raised intracranial pressure (ICP) is often interpreted as resulting from either relative brain atrophy, arrested "benign" hydrocephalus, or "successful" endoscopic third ventriculostomy (ETV). We hypothesise that the typical ICP "signature" found in symptomatic hydrocephalus can be present in asymptomatic or oligosymptomatic children, indicating pressure-compensated, but active hydrocephalus. METHODS A total of 37 children fulfilling the mentioned criteria underwent computerised ICP overnight monitoring (ONM). Fifteen children had previous hydrocephalus treatment. ICP was analysed for nocturnal dynamics of ICP, ICP amplitudes (AMP), magnitude of slow waves (SLOW), and ICP/AMP correlation index RAP. Depending on the ONM results, children were either treated or observed. The ventricular width was determined at the time of ONM and at 1-year follow-up. RESULTS The recordings of 14 children (group A) were considered normal. In the 23 children with pathologic recordings (group B), all ICP values and dependent variables (AMP, SLOW) were significantly higher, except for RAP. In group B, 12 of 15 children had received a pre-treatment and 11 of 22 without previous treatment. All group B children received treatment for hydrocephalus and showed a significant reduction of frontal-occipital horn ratio at 1 year. During follow-up, a positive neurological development was seen in 74% of children of group A and 100% of group B. CONCLUSION Ventriculomegaly in the absence of signs and symptoms of raised ICP was associated in 62% of cases to pathological ICP dynamics. In 80% of pre-treated cases, ETV or shunt failure was found. Treating children with abnormal ICP dynamics resulted in an outcome at least as favourable as in the group with normal ICP dynamics. Thus, asymptomatic ventriculomegaly in children deserves further investigation and, if associated with abnormal ICP dynamics, should be treated in order to provide a normalised intracranial physiology as basis for best possible long-term outcome.
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Affiliation(s)
- Sandra F Dias
- Section of Paediatric Neurosurgery, Department of Neurosurgery, University Hospital of Tübingen, Tübingen, Germany. .,Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland.
| | - Elisabeth Jehli
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
| | - Karin Haas-Lude
- Department of Paediatric Neurology, University Children's Hospital of Tübingen, Tübingen, Germany
| | - Andrea Bevot
- Department of Paediatric Neurology, University Children's Hospital of Tübingen, Tübingen, Germany
| | - Humphrey Okechi
- Section of Paediatric Neurosurgery, Department of Neurosurgery, University Hospital of Tübingen, Tübingen, Germany
| | - Julian Zipfel
- Section of Paediatric Neurosurgery, Department of Neurosurgery, University Hospital of Tübingen, Tübingen, Germany
| | - Martin U Schuhmann
- Section of Paediatric Neurosurgery, Department of Neurosurgery, University Hospital of Tübingen, Tübingen, Germany
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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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Liu X, Vitt JR, Hetts SW, Gudelunas K, Ho N, Ko N, Hu X. Morphological changes of intracranial pressure quantifies vasodilatory effect of verapamil to treat cerebral vasospasm. J Neurointerv Surg 2020; 12:802-808. [PMID: 31959633 DOI: 10.1136/neurintsurg-2019-015499] [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: 10/04/2019] [Revised: 12/18/2019] [Accepted: 01/05/2020] [Indexed: 11/04/2022]
Abstract
INTRODUCTION After aneurysmal subarachnoid hemorrhage (SAH), both proximal and distal cerebral vasospasm can contribute to the development of delayed cerebral ischemia. Intra-arterial (IA) vasodilators are a mainstay of treatment for distal arterial vasospasm, but no methods of assessing the efficacy of interventions in real time have been established. OBJECTIVE To introduce a new method for continuous intraprocedural assessment of endovascular treatment for cerebral vasospasm. METHODS The premise of our approach was that distal cerebral arterial changes induce a consistent pattern in the morphological changes of intracranial pressure (ICP) pulse. This premise was demonstrated using a published algorithm in previous papers. In this study, we applied the algorithm to calculate the likelihood of cerebral vasodilation (VDI) and cerebral vasoconstriction (VCI) from intraprocedural ICP signals that are synchronized with injection of the IA vasodilator, verapamil. Cerebral blood flow velocities (CBFVs) on bilateral cerebral arteries were studied before and after IA therapy. RESULTS 192 recordings of patients with SAH were reviewed, and 27 recordings had high-quality ICP waveforms. The VCI was significantly lower after the first verapamil injection (0.47±0.017) than VCI at baseline (0.49±0.020, p<0.001). A larger dose of injected verapamil resulted in a larger and longer VDI increase. CBFV of the middle cerebral artery increases across the days before the injection of verapamil and decreases after IA therapy. CONCLUSION This study provides preliminary validation of an algorithm for continuous assessment of distal cerebral arterial changes in response to IA vasodilator infusion in patients with vasospasm and aneurysmal SAH.
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Affiliation(s)
- Xiuyun Liu
- School of Physiological Nursing, UCSF, San Francisco, California, USA
| | - Jeffrey R Vitt
- School of Physiological Nursing, UCSF, San Francisco, California, USA
| | - Steven W Hetts
- Department of Radiology, UCSF, San Francisco, California, USA
| | - Koa Gudelunas
- School of Physiological Nursing, UCSF, San Francisco, California, USA
| | - Nhi Ho
- School of Physiological Nursing, UCSF, San Francisco, California, USA
| | - Nerissa Ko
- School of Physiological Nursing, UCSF, San Francisco, California, USA
| | - Xiao Hu
- School of Physiological Nursing, UCSF, San Francisco, California, USA
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Martinez-Tejada I, Arum A, Wilhjelm JE, Juhler M, Andresen M. B waves: a systematic review of terminology, characteristics, and analysis methods. Fluids Barriers CNS 2019; 16:33. [PMID: 31610775 PMCID: PMC6792201 DOI: 10.1186/s12987-019-0153-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/15/2019] [Indexed: 11/18/2022] Open
Abstract
Background Although B waves were introduced as a concept in the analysis of intracranial pressure (ICP) recordings nearly 60 years ago, there is still a lack consensus on precise definitions, terminology, amplitude, frequency or origin. Several competing terms exist, addressing either their probable physiological origin or their physical characteristics. To better understand B wave characteristics and ease their detection, a literature review was carried out. Methods A systematic review protocol including search strategy and eligibility criteria was prepared in advance. A literature search was carried out using PubMed/MEDLINE, with the following search terms: B waves + review filter, slow waves + review filter, ICP B waves, slow ICP waves, slow vasogenic waves, Lundberg B waves, MOCAIP. Results In total, 19 different terms were found, B waves being the most common. These terminologies appear to be interchangeable and seem to be used indiscriminately, with some papers using more than five different terms. Definitions and etiologies are still unclear, which makes systematic and standardized detection difficult. Conclusions Two future lines of action are available for automating macro-pattern identification in ICP signals: achieving strict agreement on morphological characteristics of “traditional” B waveforms, or starting a new with a fresh computerized approach for recognition of new clinically relevant patterns.
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Affiliation(s)
- Isabel Martinez-Tejada
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark. .,Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark.
| | - Alexander Arum
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Jens E Wilhjelm
- Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Marianne Juhler
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Morten Andresen
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
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7
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Long J, Lin H, Cao G, Wang MZ, Huang XJ, Xia J, Sun Z. Relationship between intracranial pressure and phase-contrast cine MRI-derived measures of cerebrospinal fluid parameters in communicating hydrocephalus. Quant Imaging Med Surg 2019; 9:1413-1420. [PMID: 31559170 DOI: 10.21037/qims.2019.08.04] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Background To explore the correlation between intracranial pressure (ICP) and cerebrospinal fluid (CSF) parameters assessed by phase-contrast cine MRI (PC-MRI). Methods Fifteen normal people and 80 subjects with communicating hydrocephalus who underwent PC-MRI examinations from a single center were included in this cross-sectional study. In addition to recording patient's age, heart rate, blood pressure and body mass index (BMI), ICP and CSF hemodynamic parameters, such as flow velocity and aqueduct diameter, were measured for correlation analysis. Results The mean ICP and CSF aqueduct diameter in hydrocephalus patients were 151.05 mmH2O and 2.877 mm, respectively, and the maximum (6.938 cm/s) and mean (0.845 cm/s) CSF flow velocities were significantly higher in these patients compared with the controls (P<0.05). After adjusting for age, heart rate, blood pressure, and BMI, there was no significant relationship between peak velocity and ICP (P>0.05). Furthermore, a nonlinear relationship was observed between the ICP and the average velocity of CSF, and the ICP and aqueduct diameter. The ICP increased with the average velocity above 1.628 cm/s (P≤0.01), and the aqueduct diameter increased more than 3.6 mm (P<0.001). Conclusions This study found significant correlations between ICP and average velocity and aqueduct diameter. These findings can be useful in assisting clinicians in predicting ICP more effectively, thus improving patient management.
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Affiliation(s)
- Jia Long
- Department of Radiology, The First Affiliated Hospital of Shenzhen University/Shenzhen Second People's Hospital, Shenzhen University Health Science Center, Shenzhen 518035, China
| | - Hai Lin
- Department of Neurosurgery, The First Affiliated Hospital of Shenzhen University/Shenzhen Second People's Hospital, Shenzhen University Health Science Center, Shenzhen 518035, China
| | - Gan Cao
- Department of Radiology, Shenzhen Second People's Hospital, Clinical Medicine College of Anhui Medical University, Shenzhen 518000, China
| | - Meng-Zhu Wang
- MR Scientific Marketing, Siemens Healthineers, Guangzhou 510145, China
| | - Xian-Jian Huang
- Department of Neurosurgery, The First Affiliated Hospital of Shenzhen University/Shenzhen Second People's Hospital, Shenzhen University Health Science Center, Shenzhen 518035, China
| | - Jun Xia
- Department of Radiology, The First Affiliated Hospital of Shenzhen University/Shenzhen Second People's Hospital, Shenzhen University Health Science Center, Shenzhen 518035, China
| | - Zhonghua Sun
- Discipline of Medical Radiation Sciences, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
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Thibeault CM, Thorpe S, Canac N, Wilk SJ, Hamilton RB. Sex-Based Differences in Transcranial Doppler Ultrasound and Self-Reported Symptoms After Mild Traumatic Brain Injury. Front Neurol 2019; 10:590. [PMID: 31244755 PMCID: PMC6579811 DOI: 10.3389/fneur.2019.00590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/20/2019] [Indexed: 11/26/2022] Open
Abstract
The possibility of sex-related differences in mild traumatic brain injury (mTBI) severity and recovery remains a controversial subject. With some studies showing that female subjects suffer a longer period of symptom recovery, while others have failed to demonstrate differences. In this study, we explored the sex-related effects of mTBI on self-reported symptoms and transcranial Doppler ultrasound (TCD) measured features in an adolescent population. Fifty-eight subjects were assessed—at different points post-injury—after suffering an mTBI. Subjects answered a series of symptom questions before the velocity from the middle cerebral artery was measured. Subjects participated in breath-holding challenges to evaluate cerebrovascular reactivity. The Pulsatility Index (PI), the ratio of the first peaks (P2R), and the Breath-Hold Index (BHI), were computed. Linear mixed effects models were developed to explore the interactions between measured features, sex, and time since injury while accounting for within subject variation. Over the first 10 days post-injury, the female group had significant interactions between sex and time since injury that was not present in the TCD features. This is the first study to compare sex-related differences in self-reported symptoms and TCD measurements in adolescents suffering an mTBI. It illustrates the pitfalls clinicians face when relying on subjective measures alone during diagnosis and tracking of mTBI patients. In addition, it highlights the need for more focused research on sex-related differences in concussion pathophysiology.
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Affiliation(s)
| | - Samuel Thorpe
- Neural Analytics, Inc., Los Angeles, CA, United States
| | - Nicolas Canac
- Neural Analytics, Inc., Los Angeles, CA, United States
| | - Seth J Wilk
- Neural Analytics, Inc., Los Angeles, CA, United States
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Thibeault CM, Thorpe S, Canac N, O’Brien MJ, Ranjbaran M, Wilk SJ, Hamilton RB. A model of longitudinal hemodynamic alterations after mild traumatic brain injury in adolescents. JOURNAL OF CONCUSSION 2019. [DOI: 10.1177/2059700219838654] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
There is an unquestionable need for quantitative biomarkers of mild traumatic brain injuries. Something that is particularly true for adolescents – where the recovery from these injuries is still poorly understood. However, within this population, it is clear that the vasculature is distinctly affected by a mild traumatic brain injury. In addition, our group recently demonstrated how that effect appears to show a progression of alterations similar but in contrast to that found in severe traumatic injuries. Through measuring an adolescent population with transcranial Doppler ultrasound during a hypercapnia challenge, multiple phases of hemodynamic dysfunction were suggested. Here, we create a generalized model of the hemodynamic responses by fitting a set of inverse models to the dominant features from that work. The resulting model helps define the multiple phases of hemodynamic recovery after a mild traumatic brain injury. This can eventually be generalized, potentially providing a diagnostic tool for clinicians tracking patient’s recovery, and ultimately, resulting in more informed decisions and better outcomes.
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Megjhani M, Alkhachroum A, Terilli K, Ford J, Rubinos C, Kromm J, Wallace BK, Connolly ES, Roh D, Agarwal S, Claassen J, Padmanabhan R, Hu X, Park S. An active learning framework for enhancing identification of non-artifactual intracranial pressure waveforms. Physiol Meas 2019; 40:015002. [PMID: 30562165 DOI: 10.1088/1361-6579/aaf979] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Intracranial pressure (ICP) is an important and established clinical measurement that is used in the management of severe acute brain injury. ICP waveforms are usually triphasic and are susceptible to artifact because of transient catheter malfunction or routine patient care. Existing methods for artifact detection include threshold-based, stability-based, or template matching, and result in higher false positives (when there is variability in the ICP waveforms) or higher false negatives (when the ICP waveforms lack complete triphasic components but are valid). APPROACH We hypothesized that artifact labeling of ICP waveforms can be optimized by an active learning approach which includes interactive querying of domain experts to identify a manageable number of informative training examples. MAIN RESULTS The resulting active learning based framework identified non-artifactual ICP pulses with a superior AUC of 0.96 + 0.012, compared to existing methods: template matching (AUC: 0.71 + 0.04), ICP stability (AUC: 0.51 + 0.036) and threshold-based (AUC: 0.5 + 0.02). SIGNIFICANCE The proposed active learning framework will support real-time ICP-derived analytics by improving precision of artifact-labelling.
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Affiliation(s)
- Murad Megjhani
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States of America
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Thibeault CM, Thorpe S, O'Brien MJ, Canac N, Ranjbaran M, Patanam I, Sarraf A, LeVangie J, Scalzo F, Wilk SJ, Diaz-Arrastia R, Hamilton RB. A Cross-Sectional Study on Cerebral Hemodynamics After Mild Traumatic Brain Injury in a Pediatric Population. Front Neurol 2018; 9:200. [PMID: 29674994 PMCID: PMC5895751 DOI: 10.3389/fneur.2018.00200] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 03/14/2018] [Indexed: 02/03/2023] Open
Abstract
The microvasculature is prominently affected by traumatic brain injury (TBI), including mild TBI (concussion). Assessment of cerebral hemodynamics shows promise as biomarkers of TBI, and may help inform development of therapies aimed at promoting neurologic recovery. The objective of this study was to assess the evolution in cerebral hemodynamics observable with transcranial Doppler (TCD) ultrasound in subjects suffering from a concussion at different intervals during recovery. Pediatric subjects between the ages of 14 and 19 years clinically diagnosed with a concussion were observed at different points post-injury. Blood flow velocity in the middle cerebral artery was measured with TCD. After a baseline period, subjects participated in four breath holding challenges. Pulsatility index (PI), resistivity index (RI), the ratio of the first two pulse peaks (P2R), and the mean velocity (MV) were computed from the baseline section. The breath hold index (BHI) was computed from the challenge sections. TCD detected two phases of hemodynamic changes after concussion. Within the first 48 h, PI, RI, and P2R show a significant difference from the controls (U = −3.10; P < 0.01, U = −2.86; P < 0.01, and U = 2.62; P < 0.01, respectively). In addition, PI and P2R were not correlated (rp = −0.36; P = 0.23). After 48 h, differences in pulsatile features were no longer observable. However, BHI was significantly increased when grouped as 2–3, 4–5, and 6–7 days post-injury (U = 2.72; P < 0.01, U = 2.46; P = 0.014, and U = 2.38; P = 0.018, respectively). To our knowledge, this is the first longitudinal study of concussions using TCD. In addition, these results are the first to suggest the multiple hemodynamic changes after a concussion are observable with TCD and could ultimately lead to a better understanding of the underlying pathophysiology. In addition, the different hemodynamic responses to a concussion as compared to severe traumatic brain injuries highlight the need for specific diagnostic and therapeutic treatments of mild head injuries in adolescents.
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Affiliation(s)
| | - Samuel Thorpe
- Neural Analytics, Inc., Los Angeles, CA, United States
| | | | - Nicolas Canac
- Neural Analytics, Inc., Los Angeles, CA, United States
| | | | - Ilyas Patanam
- Neural Analytics, Inc., Los Angeles, CA, United States
| | | | | | - Fabien Scalzo
- Departments of Neurology and Computer Science, University of California, Los Angeles, CA, United States
| | - Seth J Wilk
- Neural Analytics, Inc., Los Angeles, CA, United States
| | - Ramon Diaz-Arrastia
- Penn Presbyterian Medical Center, University of Pennsylvania Hospital, Philadelphia, PA, United States
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12
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Arroyo-Palacios J, Rudz M, Fidler R, Smith W, Ko N, Park S, Bai Y, Hu X. Characterization of Shape Differences Among ICP Pulses Predicts Outcome of External Ventricular Drainage Weaning Trial. Neurocrit Care 2017; 25:424-433. [PMID: 27106888 DOI: 10.1007/s12028-016-0268-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND External ventricular drains (EVD) are widely used to manage intracranial pressure (ICP) and hydrocephalus for aneurysmal subarachnoid hemorrhage (aSAH) patients. After days of use, a decision is made to remove the EVD or replace it with a shunt, involving EVD weaning and CT imaging to observe ventricular size and clinical status. This practice may lead to prolonged hospital stay, extra radiation exposure, and neurological insult due to ICP elevation. This study aims to apply a validated morphological clustering analysis of ICP pulse (MOCAIP) algorithm to detect signatures from the pulse waveform to differentiate an intact CSF circulatory system from an abnormal one during EVD weaning. METHODS We performed a retrospective study with 50 aSAH patients with reported weaning trial admitted to our institution between 03/2013 and 08/2014. By reviewing clinical notes and pre/post-brain imaging results, 32 patients were determined as having passed the weaning trial and 18 patients as having failed the trial. MOCAIP algorithm was applied to ICP signals to form a series of artifact-free dominant pulses. Finally, pulses with similar mean ICP were identified, and amplitude, Euclidean, and geodesic inter-pulse distances were calculated in a 4-h moving window. RESULTS While the traditional measure of mean ICP failed to differentiate the two groups of patients, the proposed amplitude and morphological inter-pulse measures presented significant differences (p ≤ 0.004). Moreover, receiver operating characteristic (ROC) analyses showed their usability to predict the outcome of the EVD weaning trial (AUC 0.85, p < 0.001). CONCLUSIONS Patients with an impaired CSF system showed a larger mean and variability of inter-pulse distances, indicating frequent changes on the morphology of pulses. This technique may provide a method to rapidly determine if patients will need placement of a shunt or can simply have the EVD removed.
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Affiliation(s)
- Jorge Arroyo-Palacios
- Department of Physiological Nursing, School of Nursing, University of California, 2 Koret Way, San Francisco, CA, 94143, USA
| | - Maryna Rudz
- Department of Physiological Nursing, School of Nursing, University of California, 2 Koret Way, San Francisco, CA, 94143, USA
| | - Richard Fidler
- Department of Physiological Nursing, School of Nursing, University of California, 2 Koret Way, San Francisco, CA, 94143, USA
| | - Wade Smith
- Department of Neurology, School of Medicine, University of California, San Francisco, CA, USA
| | - Nerissa Ko
- Department of Neurology, School of Medicine, University of California, San Francisco, CA, USA
| | - Soojin Park
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yong Bai
- Department of Physiological Nursing, School of Nursing, University of California, 2 Koret Way, San Francisco, CA, 94143, USA
| | - Xiao Hu
- Department of Physiological Nursing, School of Nursing, University of California, 2 Koret Way, San Francisco, CA, 94143, USA.
- Department of Neurological Surgery, School of Medicine, University of California, San Francisco, CA, USA.
- Institute of Computational Health Sciences, University of California, San Francisco, CA, USA.
- Department of Neurosurgery, School of Medicine, University of California, Los Angeles, CA, USA.
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13
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Kramer LA, Hasan KM, Sargsyan AE, Marshall-Goebel K, Rittweger J, Donoviel D, Higashi S, Mwangi B, Gerlach DA, Bershad EM. Quantitative MRI volumetry, diffusivity, cerebrovascular flow, and cranial hydrodynamics during head-down tilt and hypercapnia: the SPACECOT study. J Appl Physiol (1985) 2017; 122:1155-1166. [DOI: 10.1152/japplphysiol.00887.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/24/2017] [Accepted: 02/11/2017] [Indexed: 01/17/2023] Open
Abstract
To improve the pathophysiological understanding of visual changes observed in astronauts, we aimed to use quantitative MRI to measure anatomic and physiological responses during a ground-based spaceflight analog (head-down tilt, HDT) combined with increased ambient carbon dioxide (CO2). Six healthy, male subjects participated in the double-blinded, randomized crossover design study with two conditions: 26.5 h of −12° HDT with ambient air and with 0.5% CO2, both followed by 2.5-h exposure to 3% CO2. Volume and mean diffusivity quantification of the lateral ventricle and phase-contrast flow sequences of the internal carotid arteries and cerebral aqueduct were acquired at 3 T. Compared with supine baseline, HDT (ambient air) resulted in an increase in lateral ventricular volume ( P = 0.03). Cerebral blood flow, however, decreased with HDT in the presence of either ambient air or 0.5% CO2( P = 0.002 and P = 0.01, respectively); this was partially reversed by acute 3% CO2exposure. Following HDT (ambient air), exposure to 3% CO2increased aqueductal cerebral spinal fluid velocity amplitude ( P = 0.01) and lateral ventricle cerebrospinal fluid (CSF) mean diffusivity ( P = 0.001). We concluded that HDT causes alterations in cranial anatomy and physiology that are associated with decreased craniospinal compliance. Brief exposure to 3% CO2augments CSF pulsatility within the cerebral aqueduct and lateral ventricles.NEW & NOTEWORTHY Head-down tilt causes increased lateral ventricular volume and decreased cerebrovascular flow after 26.5 h. Additional short exposure to 3% ambient carbon dioxide levels causes increased cerebrovascular flow associated with increased cerebrospinal fluid pulsatility at the cerebral aqueduct. Head-down tilt with chronically elevated 0.5% ambient carbon dioxide and acutely elevated 3% ambient carbon dioxide causes increased mean diffusivity of cerebral spinal fluid within the lateral ventricles.
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Affiliation(s)
- Larry A. Kramer
- Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas
| | - Khader M. Hasan
- Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas
| | | | - Karina Marshall-Goebel
- Division of Space Physiology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Department of Medicine, University of Cologne, Cologne, Germany
| | - Jörn Rittweger
- Division of Space Physiology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Department of Neurology, University of Cologne, Cologne, Germany
| | - Dorit Donoviel
- Department of Pharmacology and Space Medicine, Baylor College of Medicine, Houston, Texas
| | - Saki Higashi
- Tokushima University Medical School, Tokushima, Japan
| | - Benson Mwangi
- Department of Behavioral Sciences, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas; and
| | - Darius A. Gerlach
- Division of Space Physiology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Eric M. Bershad
- Neurology and Space Medicine, Baylor College of Medicine, Houston, Texas
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14
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Bedussi B, van der Wel NN, de Vos J, van Veen H, Siebes M, VanBavel E, Bakker EN. Paravascular channels, cisterns, and the subarachnoid space in the rat brain: A single compartment with preferential pathways. J Cereb Blood Flow Metab 2017; 37:1374-1385. [PMID: 27306753 PMCID: PMC5453458 DOI: 10.1177/0271678x16655550] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent evidence suggests an extensive exchange of fluid and solutes between the subarachnoid space and the brain interstitium, involving preferential pathways along blood vessels. We studied the anatomical relations between brain vasculature, cerebrospinal fluid compartments, and paravascular spaces in male Wistar rats. A fluorescent tracer was infused into the cisterna magna, without affecting intracranial pressure. Tracer distribution was analyzed using a 3D imaging cryomicrotome, confocal microscopy, and correlative light and electron microscopy. We found a strong 3D colocalization of tracer with major arteries and veins in the subarachnoid space and large cisterns, attributed to relatively large subarachnoid space volumes around the vessels. Confocal imaging confirmed this colocalization and also revealed novel cisternal connections between the subarachnoid space and ventricles. Unlike the vessels in the subarachnoid space, penetrating arteries but not veins were surrounded by tracer. Correlative light and electron microscopy images indicated that this paravascular space was located outside of the endothelial layer in capillaries and just outside of the smooth muscle cells in arteries. In conclusion, the cerebrospinal fluid compartment, consisting of the subarachnoid space, cisterns, ventricles, and para-arteriolar spaces, forms a continuous and extensive network that surrounds and penetrates the rat brain, in which mixing may facilitate exchange between interstitial fluid and cerebrospinal fluid.
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Affiliation(s)
- Beatrice Bedussi
- 1 Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
| | - Nicole N van der Wel
- 2 Department of Cell Biology and Histology, Electron Microscopy Centre Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Judith de Vos
- 1 Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
| | - Henk van Veen
- 2 Department of Cell Biology and Histology, Electron Microscopy Centre Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Maria Siebes
- 1 Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
| | - Ed VanBavel
- 1 Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
| | - Erik Ntp Bakker
- 1 Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
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15
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The Cerebral Surfactant System and Its Alteration in Hydrocephalic Conditions. PLoS One 2016; 11:e0160680. [PMID: 27656877 PMCID: PMC5033422 DOI: 10.1371/journal.pone.0160680] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 07/24/2016] [Indexed: 01/06/2023] Open
Abstract
Introduction Pulmonary Surfactant reduces surface tension in the terminal airways thus facilitating breathing and contributes to host’s innate immunity. Surfactant Proteins (SP) A, B, C and D were recently identified as inherent proteins of the CNS. Aim of the study was to investigate cerebrospinal fluid (CSF) SP levels in hydrocephalus patients compared to normal subjects. Patients and Methods CSF SP A-D levels were quantified using commercially available ELISA kits in 126 patients (0–84 years, mean 39 years). 60 patients without CNS pathologies served as a control group. Hydrocephalus patients were separated in aqueductal stenosis (AQS, n = 24), acute hydrocephalus without aqueductal stenosis (acute HC w/o AQS, n = 16) and idiopathic normal pressure hydrocephalus (NPH, n = 20). Furthermore, six patients with pseudotumor cerebri were investigated. Results SP A—D are present under physiological conditions in human CSF. SP-A is elevated in diseases accompanied by ventricular enlargement (AQS, acute HC w/o AQS) in a significant manner (0.67, 1.21 vs 0.38 ng/ml in control, p<0.001). SP-C is also elevated in hydrocephalic conditions (AQS, acute HC w/o AQS; 0.87, 1.71 vs. 0.48 ng/ml in controls, p<0.001) and in Pseudotumor cerebri (1.26 vs. 0.48 ng/ml in controls, p<0.01). SP-B and SP-D did not show significant alterations. Conclusion The present study confirms the presence of SPs in human CSF. There are significant changes of SP-A and SP-C levels in diseases affecting brain water circulation and elevation of intracranial pressure. Cause of the alterations, underlying regulatory mechanisms, as well as diagnostic and therapeutic consequences of cerebral SP’s requires further thorough investigations.
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16
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Kasprowicz M, Lalou DA, Czosnyka M, Garnett M, Czosnyka Z. Intracranial pressure, its components and cerebrospinal fluid pressure-volume compensation. Acta Neurol Scand 2016; 134:168-80. [PMID: 26666840 DOI: 10.1111/ane.12541] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2015] [Indexed: 11/29/2022]
Abstract
Clinical measurement of intracranial pressure (ICP) is often performed to aid diagnosis of hydrocephalus. This review discusses analysis of ICP and its components' for the investigation of cerebrospinal fluid (CSF) dynamics. The role of pulse, slow and respiratory waveforms of ICP in diagnosis, prognostication and management of hydrocephalus is presented. Two methods related to ICP measurement are listed: an overnight monitoring of ICP and a constant-rate infusion study. Due to the dynamic nature of ICP, a 'snapshot' manometric measurement of ICP is of limited use as it might lead to unreliable results. Therefore, monitoring of ICP over longer time combined with analysis of its waveforms provides more detailed information on the state of pressure-volume compensation. The infusion study implements ICP signal processing and CSF circulation model analysis in order to assess the cerebrospinal dynamics variables, such as CSF outflow resistance, compliance of CSF space, pressure amplitude, reference pressure, and CSF formation. These parameters act as an aid tool in diagnosis and prognostication of hydrocephalus and can be helpful in the assessment of a shunt malfunction.
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Affiliation(s)
- M. Kasprowicz
- Department of Biomedical Engineering; Wroclaw University of Technology; Wroclaw Poland
| | - D. A. Lalou
- National and Kapodistran University Medical School; Athens Greece
| | - M. Czosnyka
- Brain Physics Laboratory; Division of Neurosurgery; University of Cambridge Department of Clinical Neuroscience; Cambridge UK
- Institute of Electronic Systems; Warsaw University of Technology; Warsaw Poland
| | - M. Garnett
- Nerosurgery; Addenbrooke's Hospital; Cambridge UK
| | - Z. Czosnyka
- Brain Physics Laboratory; Division of Neurosurgery; University of Cambridge Department of Clinical Neuroscience; Cambridge UK
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17
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Puy V, Zmudka-Attier J, Capel C, Bouzerar R, Serot JM, Bourgeois AM, Ausseil J, Balédent O. Interactions between Flow Oscillations and Biochemical Parameters in the Cerebrospinal Fluid. Front Aging Neurosci 2016; 8:154. [PMID: 27445797 PMCID: PMC4925673 DOI: 10.3389/fnagi.2016.00154] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 06/14/2016] [Indexed: 01/02/2023] Open
Abstract
The equilibrium between the ventricular and lumbar cerebrospinal fluid (CSF) compartments may be disturbed (in terms of flow and biochemistry) in patients with chronic hydrocephalus (CH). Using flow magnetic resonance imaging (MRI) and CSF assays, we sought to determine whether changes in CSF were associated with biochemical alterations. Nine elderly patients with CH underwent phase-contrast MRI. An index of CSF dynamics (Idyn) was defined as the product of the lumbar and ventricular CSF flows. During surgery, samples of CSF were collected from the lumbar and ventricular compartments and assayed for chloride, glucose and total protein. The lumbar/ventricular (L/V) ratio was calculated for each analyte. The ratio between measured and expected levels (Ibioch) was calculated for each analyte and compared with Idyn. Idyn varied from 0 to 100.10(3)μl(2).s(2). In contrast to the L/V ratios for chloride and glucose, the L/V ratio for total protein varied markedly from one patient to another (mean ± standard deviation (SD): 2.63 ± 1.24). The Ibioch for total protein was strongly correlated with the corresponding Idyn (Spearman's R: 0.98; p < 5 × 10(-5)).We observed correlated alterations in CSF flow and biochemical parameters in patients with CH. Our findings also highlight the value of dynamic flow analysis in the interpretation of data on CSF biochemistry.
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Affiliation(s)
- Vincent Puy
- Biochemistry Unit, CBH, Amiens University Medical CenterAmiens, France; INSERM U1088, Research GroupAmiens, France
| | - Jadwiga Zmudka-Attier
- BioFlowImage Research Group, Jules Verne University of PicardyAmiens, France; Geriatric Unit, General HospitalSaint Quentin, France
| | - Cyrille Capel
- BioFlowImage Research Group, Jules Verne University of PicardyAmiens, France; Neurosurgery Unit, Amiens University Medical CenterAmiens, France
| | - Roger Bouzerar
- BioFlowImage Research Group, Jules Verne University of PicardyAmiens, France; Medical Imaging Unit, Amiens University Medical CenterAmiens, France
| | - Jean-Marie Serot
- BioFlowImage Research Group, Jules Verne University of PicardyAmiens, France; Geriatric Unit, General HospitalSaint Quentin, France
| | | | - Jérome Ausseil
- Biochemistry Unit, CBH, Amiens University Medical CenterAmiens, France; INSERM U1088, Research GroupAmiens, France
| | - Olivier Balédent
- BioFlowImage Research Group, Jules Verne University of PicardyAmiens, France; Medical Imaging Unit, Amiens University Medical CenterAmiens, France
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18
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Raybaud C. MR assessment of pediatric hydrocephalus: a road map. Childs Nerv Syst 2016; 32:19-41. [PMID: 26337698 DOI: 10.1007/s00381-015-2888-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 08/11/2015] [Indexed: 12/12/2022]
Abstract
PURPOSE This study was conducted to design a rational approach to the MR diagnosis of hydrocephalus based on a pathophysiologic reevaluation of its possible mechanisms and to apply it to the different etiological contexts. METHOD A review of the literature reports describing new physiologic models of production and absorption and of the hydrodynamics of the CSF was made. RESULTS Besides the secretion of CSF by the choroid plexuses, and its passive, pressure-dependent transdural absorption (arachnoid villi, dural clefts, cranial, and spinal nerve sheaths), water transporters, aquaporins, allow water (if not ions and organic molecules) to exchange freely between the brain parenchyma and the CSF spaces across the ependymal and the pial interfaces (including the Virchow-Robin spaces). Consequently, the CSF bulk flow is not necessarily global, and situations of balanced absorption-secretion may occur separately in different CSF compartments such as the ventricular, intracranial, or intraspinal CSF spaces. This means that rather than from a hypothetical pressure gradient from the plexuses to the dural sinuses, the dynamics of the CSF depend on the force provided in those different compartments by the arterial systolic pulsation of the pericerebral (mostly), intracerebral, and intraventricular (choroid plexuses) vascular beds. CONCLUSION Using MR imaging, diverse varieties of hydrocephalus may tentatively be explained by applying those concepts to the correspondingly diverse causal diseases. Hopefully, this may have an impact on the choice of the treatment strategies also.
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Affiliation(s)
- Charles Raybaud
- Division of Neuroradiology, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
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19
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Syed H, Unnikrishnan VU, Olcmen S. Characteristics of time-varying intracranial pressure on blood flow through cerebral artery: A fluid–structure interaction approach. Proc Inst Mech Eng H 2015; 230:111-21. [DOI: 10.1177/0954411915619952] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 11/03/2015] [Indexed: 01/12/2023]
Abstract
Elevated intracranial pressure is a major contributor to morbidity and mortality in severe head injuries. Wall shear stresses in the artery can be affected by increased intracranial pressures and may lead to the formation of cerebral aneurysms. Earlier research on cerebral arteries and aneurysms involves using constant mean intracranial pressure values. Recent advancements in intracranial pressure monitoring techniques have led to measurement of the intracranial pressure waveform. By incorporating a time-varying intracranial pressure waveform in place of constant intracranial pressures in the analysis of cerebral arteries helps in understanding their effects on arterial deformation and wall shear stress. To date, such a robust computational study on the effect of increasing intracranial pressures on the cerebral arterial wall has not been attempted to the best of our knowledge. In this work, fully coupled fluid–structure interaction simulations are carried out to investigate the effect of the variation in intracranial pressure waveforms on the cerebral arterial wall. Three different time-varying intracranial pressure waveforms and three constant intracranial pressure profiles acting on the cerebral arterial wall are analyzed and compared with specified inlet velocity and outlet pressure conditions. It has been found that the arterial wall experiences deformation depending on the time-varying intracranial pressure waveforms, while the wall shear stress changes at peak systole for all the intracranial pressure profiles.
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Affiliation(s)
- Hasson Syed
- Department of Aerospace Engineering and Mechanics, The University of Alabama, Tuscaloosa, AL, USA
| | - Vinu U Unnikrishnan
- Department of Aerospace Engineering and Mechanics, The University of Alabama, Tuscaloosa, AL, USA
| | - Semih Olcmen
- Department of Aerospace Engineering and Mechanics, The University of Alabama, Tuscaloosa, AL, USA
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20
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Ringstad G, Emblem KE, Geier O, Alperin N, Eide PK. Aqueductal Stroke Volume: Comparisons with Intracranial Pressure Scores in Idiopathic Normal Pressure Hydrocephalus. AJNR Am J Neuroradiol 2015; 36:1623-30. [PMID: 25977480 DOI: 10.3174/ajnr.a4340] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/11/2015] [Indexed: 01/23/2023]
Abstract
BACKGROUND AND PURPOSE Aqueductal stroke volume from phase-contrast MR imaging has been proposed for predicting shunt response in normal pressure hydrocephalus. However, this biomarker has remained controversial in use and has a lack of validation with invasive intracranial monitoring. We studied how aqueductal stroke volume compares with intracranial pressure scores in the presurgical work-up and clinical score, ventricular volume, and aqueduct area and assessed the patient's response to shunting. MATERIALS AND METHODS Phase-contrast MR imaging was performed in 21 patients with probable idiopathic normal pressure hydrocephalus. Patients were selected for shunting on the basis of pathologically increased intracranial pressure pulsatility. Patients with shunts were offered a second MR imaging after 12 months. Ventricular volume and transverse aqueductal area were calculated, as well as clinical symptom score. RESULTS No correlations between aqueductal stroke volume and preoperative scores of mean intracranial pressure or mean wave amplitudes were observed. Preoperative aqueductal stroke volume was not different between patients with shunts and conservatively treated patients (P = .69) but was correlated with ventricular volume (R = 0.60, P = .004) and aqueductal area (R = 0.58, P = .006) but not with the severity or duration of clinical symptoms. After shunting, aqueductal stroke volume (P = .006) and ventricular volume (P = .002) were reduced. A clinical improvement was seen in 16 of 17 patients who had shunts (94%). CONCLUSIONS Aqueductal stroke volume does not reflect intracranial pressure pulsatility or symptom score, but rather aqueduct area and ventricular volume. The results do not support the use of aqueductal stroke volume for selecting patients for shunting.
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Affiliation(s)
- G Ringstad
- From the Department of Radiology and Nuclear Medicine (G.R.)
| | - K E Emblem
- Intervention Centre (K.E.E., O.G.), Oslo University Hospital-Rikshospitalet, Oslo, Norway
| | - O Geier
- Intervention Centre (K.E.E., O.G.), Oslo University Hospital-Rikshospitalet, Oslo, Norway
| | - N Alperin
- Department of Radiology (N.A.), University of Miami Miller School of Medicine, Miami, Florida
| | - P K Eide
- Department of Neurosurgery (P.K.E.), Oslo University Hospital, Oslo, Norway Faculty of Medicine (P.K.E.), University of Oslo, Oslo, Norway
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21
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Yu L, Kim BJ, Meng E. Chronically implanted pressure sensors: challenges and state of the field. SENSORS 2014; 14:20620-44. [PMID: 25365461 PMCID: PMC4279503 DOI: 10.3390/s141120620] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 10/14/2014] [Accepted: 10/21/2014] [Indexed: 12/12/2022]
Abstract
Several conditions and diseases are linked to the elevation or depression of internal pressures from a healthy, normal range, motivating the need for chronic implantable pressure sensors. A simple implantable pressure transduction system consists of a pressure-sensing element with a method to transmit the data to an external unit. The biological environment presents a host of engineering issues that must be considered for long term monitoring. Therefore, the design of such systems must carefully consider interactions between the implanted system and the body, including biocompatibility, surgical placement, and patient comfort. Here we review research developments on implantable sensors for chronic pressure monitoring within the body, focusing on general design requirements for implantable pressure sensors as well as specifications for different medical applications. We also discuss recent efforts to address biocompatibility, efficient telemetry, and drift management, and explore emerging trends.
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Affiliation(s)
- Lawrence Yu
- Department of Biomedical Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA 90089-1111, USA.
| | - Brian J Kim
- Department of Biomedical Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA 90089-1111, USA.
| | - Ellis Meng
- Department of Biomedical Engineering, University of Southern California, 1042 Downey Way, DRB-140, Los Angeles, CA 90089-1111, USA.
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22
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CSF dynamic analysis of a predictive pulsatility-based infusion test for normal pressure hydrocephalus. Med Biol Eng Comput 2013; 52:75-85. [DOI: 10.1007/s11517-013-1110-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 09/01/2013] [Indexed: 10/26/2022]
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23
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Tain RW, Alperin N. Intracranial pressure dynamics are not linked to aqueductal cerebrospinal fluid stroke volume. J Appl Physiol (1985) 2013; 114:1645. [PMID: 23729634 DOI: 10.1152/japplphysiol.00357.2013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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