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Betsholtz C, Engelhardt B, Koh GY, McDonald DM, Proulx ST, Siegenthaler J. Advances and controversies in meningeal biology. Nat Neurosci 2024:10.1038/s41593-024-01701-8. [PMID: 39333784 DOI: 10.1038/s41593-024-01701-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 06/12/2024] [Indexed: 09/30/2024]
Abstract
The dura, arachnoid and pia mater, as the constituent layers of the meninges, along with cerebrospinal fluid in the subarachnoid space and ventricles, are essential protectors of the brain and spinal cord. Complemented by immune cells, blood vessels, lymphatic vessels and nerves, these connective tissue layers have held many secrets that have only recently begun to be revealed. Each meningeal layer is now known to have molecularly distinct types of fibroblasts. Cerebrospinal fluid clearance through peripheral lymphatics and lymph nodes is well documented, but its routes and flow dynamics are debated. Advances made in meningeal immune functions are also debated. This Review considers the cellular and molecular structure and function of the dura, arachnoid and pia mater in the context of conventional views, recent progress, and what is uncertain or unknown. The hallmarks of meningeal pathophysiology are identified toward developing a more complete understanding of the meninges in health and disease.
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Affiliation(s)
- Christer Betsholtz
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden and Department of Medicine-Huddinge, Karolinska Institutet, Huddinge, Sweden
| | | | - Gou Young Koh
- Center for Vascular Research, Institute for Basic Science and Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Donald M McDonald
- Department of Anatomy, Cardiovascular Research Institute, and UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA
| | - Steven T Proulx
- Theodor Kocher Institute, University of Bern, Bern, Switzerland
| | - Julie Siegenthaler
- Department of Pediatrics, Section of Developmental Biology, University of Colorado, Anschutz Medical Campus Aurora, Colorado, CO, USA.
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2
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Islam A, Froese L, Bergmann T, Gomez A, Sainbhi AS, Vakitbilir N, Stein KY, Marquez I, Ibrahim Y, Zeiler FA. Continuous monitoring methods of cerebral compliance and compensatory reserve: a scoping review of human literature. Physiol Meas 2024; 45:06TR01. [PMID: 38776946 DOI: 10.1088/1361-6579/ad4f4a] [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] [Received: 01/11/2024] [Accepted: 05/22/2024] [Indexed: 05/25/2024]
Abstract
Objective.Continuous monitoring of cerebrospinal compliance (CC)/cerebrospinal compensatory reserve (CCR) is crucial for timely interventions and preventing more substantial deterioration in the context of acute neural injury, as it enables the early detection of abnormalities in intracranial pressure (ICP). However, to date, the literature on continuous CC/CCR monitoring is scattered and occasionally challenging to consolidate.Approach.We subsequently conducted a systematic scoping review of the human literature to highlight the available continuous CC/CCR monitoring methods.Main results.This systematic review incorporated a total number of 76 studies, covering diverse patient types and focusing on three primary continuous CC or CCR monitoring metrics and methods-Moving Pearson's correlation between ICP pulse amplitude waveform and ICP, referred to as RAP, the Spiegelberg Compliance Monitor, changes in cerebral blood flow velocity with respect to the alternation of ICP measured through transcranial doppler (TCD), changes in centroid metric, high frequency centroid (HFC) or higher harmonics centroid (HHC), and the P2/P1 ratio which are the distinct peaks of ICP pulse wave. The majority of the studies in this review encompassed RAP metric analysis (n= 43), followed by Spiegelberg Compliance Monitor (n= 11), TCD studies (n= 9), studies on the HFC/HHC (n= 5), and studies on the P2/P1 ratio studies (n= 6). These studies predominantly involved acute traumatic neural injury (i.e. Traumatic Brain Injury) patients and those with hydrocephalus. RAP is the most extensively studied of the five focused methods and exhibits diverse applications. However, most papers lack clarification on its clinical applicability, a circumstance that is similarly observed for the other methods.Significance.Future directions involve exploring RAP patterns and identifying characteristics and artifacts, investigating neuroimaging correlations with continuous CC/CCR and integrating machine learning, holding promise for simplifying CC/CCR determination. These approaches should aim to enhance the precision and accuracy of the metric, making it applicable in clinical practice.
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Affiliation(s)
- Abrar Islam
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada
| | - Logan Froese
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada
| | - Tobias Bergmann
- Undergraduate Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, Canada
| | - Alwyn Gomez
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Amanjyot Singh Sainbhi
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada
| | - Nuray Vakitbilir
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada
| | - Kevin Y Stein
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Izabella Marquez
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada
| | - Younis Ibrahim
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Frederick A Zeiler
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
- Centre on Aging, University of Manitoba, Winnipeg, Canada
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Hamarat Y, Bartusis L, Putnynaite V, Zakelis R, Deimantavicius M, Zigmantaite V, Grigaleviciute R, Kucinskas A, Kalvaitis E, Ragauskas A. Intraorbital pressure-volume characteristics in a piglet model: In vivo pilot study. PLoS One 2024; 19:e0296780. [PMID: 38215081 PMCID: PMC10786399 DOI: 10.1371/journal.pone.0296780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 12/19/2023] [Indexed: 01/14/2024] Open
Abstract
Intracranial pressure measurement is frequently used for diagnosis in neurocritical care but cannot always accurately predict neurological deterioration. Intracranial compliance plays a significant role in maintaining cerebral blood flow, cerebral perfusion pressure, and intracranial pressure. This study's objective was to investigate the feasibility of transferring external pressure into the eye orbit in a large-animal model while maintaining a clinically acceptable pressure gradient between intraorbital and external pressures. The experimental system comprised a specifically designed pressure applicator that can be placed and tightly fastened onto the eye. A pressure chamber made from thin, elastic, non-allergenic film was attached to the lower part of the applicator and placed in contact with the eyelid and surrounding tissues of piglets' eyeballs. External pressure was increased from 0 to 20 mmHg with steps of 1 mmHg, from 20 to 30 mmHg with steps of 2 mmHg, and from 30 to 50 mmHg with steps of 5 mmHg. An invasive pressure sensor was used to measure intraorbital pressure directly. An equation was derived from measured intraorbital and external pressures (intraorbital pressure = 0.82 × external pressure + 3.12) and demonstrated that external pressure can be linearly transferred to orbit tissues with a bias (systematic error) of 3.12 mmHg. This is close to the initial intraorbital pressure within the range of pressures tested. We determined the relationship between intraorbital compliance and externally applied pressure. Our findings indicate that intraorbital compliance can be controlled across a wide range of 1.55 to 0.15 ml/mmHg. We observed that external pressure transfer into the orbit can be achieved while maintaining a clinically acceptable pressure gradient between intraorbital and external pressures.
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Affiliation(s)
- Yasin Hamarat
- Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Laimonas Bartusis
- Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Vilma Putnynaite
- Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Rolandas Zakelis
- Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Mantas Deimantavicius
- Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Vilma Zigmantaite
- Biological Research Center, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Ramunė Grigaleviciute
- Biological Research Center, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Audrius Kucinskas
- Biological Research Center, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Evaldas Kalvaitis
- Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Arminas Ragauskas
- Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania
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Westgate CSJ, Kamp-Jensen C, Israelsen IME, Toft-Bertelsen T, Wardman JH, Jensen CA, Styrishave B, MacAulay N, Jensen RH, Eftekhari S. Acetazolamide and topiramate lower intracranial pressure through differential mechanisms: The effect of acute and chronic administration. Br J Pharmacol 2024; 181:70-86. [PMID: 37553842 DOI: 10.1111/bph.16213] [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: 09/19/2022] [Revised: 05/24/2023] [Accepted: 07/20/2023] [Indexed: 08/10/2023] Open
Abstract
BACKGROUND AND PURPOSE Diseases of raised intracranial pressure (ICP) cause severe morbidity and mortality. Multiple drugs are utilised to lower ICP including acetazolamide and topiramate. However, the evidence for their use is unclear. We aimed to assess the ICP modulatory effects and molecular effects at the choroid plexus (CP) of acetazolamide and topiramate. EXPERIMENTAL APPROACH Female rats were implanted with telemetric ICP probes for physiological, freely moving 24/7 ICP recordings. Randomised cross-over studies were performed, where rats received acute (24 h) high doses of acetazolamide and topiramate, and chronic (10 days) clinically equivalent doses of acetazolamide and topiramate, all via oral gavage. Cerebrospinal fluid (CSF) secretion assays, and RT-qPCR and western blots on in vitro and in vivo CP, were used to investigate drug actions. KEY RESULTS We demonstrate that acetazolamide and topiramate achieved maximal ICP reduction within 120 min of administration, and in combination doubled the ICP reduction over a 24-h period. Chronic administration of acetazolamide or topiramate lowered ICP by 25%. Topiramate decreased CSF secretion by 40%. Chronic topiramate increased the gene expression of Slc12a2 and Slc4a10 and protein expression of the sodium-dependent chloride/bicarbonate exchanger (NCBE), whereas chronic acetazolamide did not affect the expression of assessed genes. CONCLUSIONS AND IMPLICATIONS Acetazolamide and topiramate are effective at lowering ICP at therapeutic levels. We provide the first evidence that topiramate lowers CSF secretion and that acetazolamide and topiramate may lower ICP via distinct molecular mechanisms. Thus, the combination of acetazolamide and topiramate may have utility for treating raised ICP.
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Affiliation(s)
- Connar Stanley James Westgate
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Copenhagen, Denmark
| | - Christina Kamp-Jensen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Copenhagen, Denmark
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ida Marchen Egerod Israelsen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Christian Ahm Jensen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Copenhagen, Denmark
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bjarne Styrishave
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Rigmor Højland Jensen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Copenhagen, Denmark
| | - Sajedeh Eftekhari
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Copenhagen, Denmark
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Kalisvaart ACJ, Abrahart AH, Coney AT, Gu S, Colbourne F. Intracranial Pressure Dysfunction Following Severe Intracerebral Hemorrhage in Middle-Aged Rats. Transl Stroke Res 2023; 14:970-986. [PMID: 36367666 PMCID: PMC10640482 DOI: 10.1007/s12975-022-01102-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/14/2022] [Accepted: 11/02/2022] [Indexed: 11/13/2022]
Abstract
Rising intracranial pressure (ICP) aggravates secondary injury and heightens risk of death following intracerebral hemorrhage (ICH). Long-recognized compensatory mechanisms that lower ICP include reduced cerebrospinal fluid and venous blood volumes. Recently, we identified another compensatory mechanism in severe stroke, a decrease in cerebral parenchymal volume via widespread reductions in cell volume and extracellular space (tissue compliance). Here, we examined how age affects tissue compliance and ICP dynamics after severe ICH in rats (collagenase model). A planned comparison to historical young animal data revealed that aged SHAMs (no stroke) had significant cerebral atrophy (9% reduction, p ≤ 0.05), ventricular enlargement (9% increase, p ≤ 0.05), and smaller CA1 neuron volumes (21%, p ≤ 0.05). After ICH in aged animals, contralateral striatal neuron density and CA1 astrocyte density significantly increased (12% for neurons, 7% for astrocytes, p ≤ 0.05 vs. aged SHAMs). Unlike young animals, other regions in aged animals did not display significantly reduced cell soma volume despite a few trends. Nonetheless, overall contralateral hemisphere volume was 10% smaller in aged ICH animals compared to aged SHAMs (p ≤ 0.05). This age-dependent pattern of tissue compliance is not due to absent ICH-associated mass effect (83.2 mm3 avg. bleed volume) as aged ICH animals had significantly elevated mean and peak ICP (p ≤ 0.01), occurrence of ICP spiking events, as well as bilateral evidence of edema (e.g., 3% in injured brain, p ≤ 0.05 vs. aged SHAMs). Therefore, intracranial compliance reserve changes with age; after ICH, these and other age-related changes may cause greater fluctuation from baseline, increasing the chance of adverse outcomes like mortality.
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Affiliation(s)
| | - Ashley H Abrahart
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
| | - Alyvia T Coney
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
| | - Sherry Gu
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Frederick Colbourne
- Department of Psychology, University of Alberta, Edmonton, AB, Canada.
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
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6
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Kazimierska A, Manet R, Vallet A, Schmidt E, Czosnyka Z, Czosnyka M, Kasprowicz M. Analysis of intracranial pressure pulse waveform in studies on cerebrospinal compliance: a narrative review. Physiol Meas 2023; 44:10TR01. [PMID: 37793420 DOI: 10.1088/1361-6579/ad0020] [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] [Received: 04/15/2023] [Accepted: 10/04/2023] [Indexed: 10/06/2023]
Abstract
Continuous monitoring of mean intracranial pressure (ICP) has been an essential part of neurocritical care for more than half a century. Cerebrospinal pressure-volume compensation, i.e. the ability of the cerebrospinal system to buffer changes in volume without substantial increases in ICP, is considered an important factor in preventing adverse effects on the patient's condition that are associated with ICP elevation. However, existing assessment methods are poorly suited to the management of brain injured patients as they require external manipulation of intracranial volume. In the 1980s, studies suggested that spontaneous short-term variations in the ICP signal over a single cardiac cycle, called the ICP pulse waveform, may provide information on cerebrospinal compensatory reserve. In this review we discuss the approaches that have been proposed so far to derive this information, from pulse amplitude estimation and spectral techniques to most recent advances in morphological analysis based on artificial intelligence solutions. Each method is presented with focus on its clinical significance and the potential for application in standard clinical practice. Finally, we highlight the missing links that need to be addressed in future studies in order for ICP pulse waveform analysis to achieve widespread use in the neurocritical care setting.
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Affiliation(s)
- Agnieszka Kazimierska
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Romain Manet
- Department of Neurosurgery B, Neurological Hospital Pierre Wertheimer, University Hospital of Lyon, Lyon, France
| | - Alexandra Vallet
- Department of Mathematics, University of Oslo, Oslo, Norway
- INSERM U1059 Sainbiose, Ecole des Mines Saint-Étienne, Saint-Étienne, France
| | - Eric Schmidt
- Department of Neurosurgery, University Hospital of Toulouse, Toulouse, France
| | - Zofia Czosnyka
- Brain Physics Laboratory, Department of Clinical Neurosciences, Division of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Marek Czosnyka
- Brain Physics Laboratory, Department of Clinical Neurosciences, Division of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
- Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Magdalena Kasprowicz
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
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7
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Stein KY, Froese L, Gomez A, Sainbhi AS, Vakitbilir N, Ibrahim Y, Zeiler FA. Intracranial Pressure Monitoring and Treatment Thresholds in Acute Neural Injury: A Narrative Review of the Historical Achievements, Current State, and Future Perspectives. Neurotrauma Rep 2023; 4:478-494. [PMID: 37636334 PMCID: PMC10457629 DOI: 10.1089/neur.2023.0031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/29/2023] Open
Abstract
Since its introduction in the 1960s, intracranial pressure (ICP) monitoring has become an indispensable tool in neurocritical care practice and a key component of the management of moderate/severe traumatic brain injury (TBI). The primary utility of ICP monitoring is to guide therapeutic interventions aimed at maintaining physiological ICP and preventing intracranial hypertension. The rationale for such ICP maintenance is to prevent secondary brain injury arising from brain herniation and inadequate cerebral blood flow. There exists a large body of evidence indicating that elevated ICP is associated with mortality and that aggressive ICP control protocols improve outcomes in severe TBI patients. Therefore, current management guidelines recommend a cerebral perfusion pressure (CPP) target range of 60-70 mm Hg and an ICP threshold of >20 or >22 mm Hg, beyond which therapeutic intervention should be initiated. Though our ability to achieve these thresholds has drastically improved over the past decades, there has been little to no change in the mortality and morbidity associated with moderate-severe TBI. This is a result of the "one treatment fits all" dogma of current guideline-based care that fails to take individual phenotype into account. The way forward in moderate-severe TBI care is through the development of continuously derived individualized ICP thresholds. This narrative review covers the topic of ICP monitoring in TBI care, including historical context/achievements, current monitoring technologies and indications, treatment methods, associations with patient outcome and multi-modal cerebral physiology, present controversies surrounding treatment thresholds, and future perspectives on personalized approaches to ICP-directed therapy.
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Affiliation(s)
- Kevin Y. Stein
- Biomedical Engineering, Price Faculty of Engineering, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Logan Froese
- Biomedical Engineering, Price Faculty of Engineering, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Alwyn Gomez
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Amanjyot Singh Sainbhi
- Biomedical Engineering, Price Faculty of Engineering, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Nuray Vakitbilir
- Biomedical Engineering, Price Faculty of Engineering, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Younis Ibrahim
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Frederick A. Zeiler
- Biomedical Engineering, Price Faculty of Engineering, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
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Nicholls JK, Turner P, Lecchini-Visintini A, Ince J, de Vries G, Cappellugola L, Oura M, Ebirim KU, Pallett E, Ramnarine KV, Chung EML. Effects of Blood Pressure on Brain Tissue Pulsation Amplitude in a Phantom Model. ULTRASOUND IN MEDICINE & BIOLOGY 2023:S0301-5629(23)00200-4. [PMID: 37400302 DOI: 10.1016/j.ultrasmedbio.2023.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 07/05/2023]
Abstract
OBJECTIVE The precise mechanism and determinants of brain tissue pulsations (BTPs) are poorly understood, and the impact of blood pressure (BP) on BTPs is relatively unexplored. This study aimed to explore the relationship between BP parameters (mean arterial pressure [MAP] and pulse pressure [PP]) and BTP amplitude, using a transcranial tissue Doppler prototype. METHODS A phantom brain model generating arterial-induced BTPs was developed to observe BP changes in the absence of confounding variables and cerebral autoregulation feedback processes. A regression model was developed to investigate the relationship between bulk BTP amplitude and BP. The separate effects of PP and MAP were evaluated and quantified. RESULTS The regression model (R2 = 0.978) revealed that bulk BTP amplitude measured from 27 gates significantly increased with PP but not with MAP. Every 1 mm Hg increase in PP resulted in a bulk BTP amplitude increase of 0.29 µm. CONCLUSION Increments in BP were significantly associated with increments in bulk BTP amplitude. Further work should aim to confirm the relationship between BP and BTPs in the presence of cerebral autoregulation and explore further physiological factors having an impact on BTP measurements, such as cerebral blood flow volume, tissue distensibility and intracranial pressure.
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Affiliation(s)
- Jennifer K Nicholls
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK
| | - Poppy Turner
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; School of Engineering, University of Leicester, Leicester, UK
| | - Andrea Lecchini-Visintini
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; School of Electronics and Computer Science, University of Southampton, Southampton, UK
| | - Jonathan Ince
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Georgina de Vries
- Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK
| | - Laurie Cappellugola
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Mitsuhiro Oura
- Nihon Kohden Corporation, Tokorozawa-shi, Saitama, Japan
| | | | - Edward Pallett
- Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK
| | - Kumar V Ramnarine
- Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK; Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Emma M L Chung
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK; NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; Faculty of Life Sciences and Medicine, King's College London, London, UK.
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9
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Westgate CSJ, Israelsen IME, Kamp-Jensen C, Jensen RH, Eftekhari S. Glucocorticoids modify intracranial pressure in freely moving rats. Fluids Barriers CNS 2023; 20:35. [PMID: 37231507 DOI: 10.1186/s12987-023-00439-y] [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: 03/17/2023] [Accepted: 05/06/2023] [Indexed: 05/27/2023] Open
Abstract
BACKGROUND Glucocorticoids (GCs) are widely prescribed for a variety of inflammatory diseases, but they are also used to treat raised intracranial pressure (ICP) caused by trauma or oedema. However, it is unclear if GCs independently modulate ICP and if GCs are involved in normal ICP regulation. In this study, we aimed to assess the ICP modulatory effects of GCs and their molecular consequences on choroid plexus (CP). METHODS Adult female rats were implanted with telemetric ICP probes for physiological, continuous ICP recordings in a freely moving setup. Rats received prednisolone or vehicle via oral gavage in a randomized acute (24 h) ICP study. In a subsequent study rats received corticosterone or vehicle in drinking water for a 4-week chronic ICP study. CP were removed, and the expression of genes associated with cerebrospinal fluid secretion were assessed. RESULTS A single prednisolone dose reduced ICP by up to 48% (P < 0.0001), where ICP was reduced within 7 h and was maintained for at least 14 h. Prednisolone increases ICP spiking (P = 0.0075) while not altering ICP waveforms. Chronic corticosterone reduces ICP by up to 44%, where ICP was lower for the entirety of the 4-week ICP recording period (P = 0.0064). ICP daily periodicity was not altered by corticosterone. Corticosterone ICP reduction was not accompanied by ICP spike differences or alteration in ICP spike periodicity. Chronic corticosterone treatment had modest effects on CP gene expression, lowering the expression of Car2 at CP (P = 0.047). CONCLUSIONS GCs reduce ICP in both the acute and chronic setting to a similar degree. Moreover, GCs did not modify the diurnal rhythm of ICP, suggesting the diurnal variation of ICP periodicity is not under explicit control of GCs. ICP disturbances should be considered a consequence of GC therapy. Based on these experiments, GCs may have broader ICP therapeutic uses, but side effects must be taken into consideration.
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Affiliation(s)
- Connar Stanley James Westgate
- Danish Headache Center, Dept of Neurology, Rigshospitalet-Glostrup, Glostrup Research Institute, University of Copenhagen, Glostrup, Denmark
| | - Ida Marchen Egerod Israelsen
- Danish Headache Center, Dept of Neurology, Rigshospitalet-Glostrup, Glostrup Research Institute, University of Copenhagen, Glostrup, Denmark
| | - Christina Kamp-Jensen
- Danish Headache Center, Dept of Neurology, Rigshospitalet-Glostrup, Glostrup Research Institute, University of Copenhagen, Glostrup, Denmark
| | - Rigmor Højland Jensen
- Danish Headache Center, Dept of Neurology, Rigshospitalet-Glostrup, Glostrup Research Institute, University of Copenhagen, Glostrup, Denmark
| | - Sajedeh Eftekhari
- Danish Headache Center, Dept of Neurology, Rigshospitalet-Glostrup, Glostrup Research Institute, University of Copenhagen, Glostrup, Denmark.
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10
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Laganà MM, Di Tella S, Ferrari F, Pelizzari L, Cazzoli M, Alperin N, Jin N, Zacà D, Baselli G, Baglio F. Blood and cerebrospinal fluid flow oscillations measured with real-time phase-contrast MRI: breathing mode matters. Fluids Barriers CNS 2022; 19:100. [PMID: 36517859 PMCID: PMC9749305 DOI: 10.1186/s12987-022-00394-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/12/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Cervical blood and cerebrospinal fluid (CSF) flow rates can be quantified with Phase-contrast (PC) MRI, which is routinely used for clinical studies. Previous MRI studies showed that venous and CSF flow alterations are linked to various pathological conditions. Since it is well known that, besides the heart beating, the thoracic pump influences the blood and CSF dynamics, we studied the effect of different respiration modes on blood and CSF flow rates using a real-time (RT)-PC prototype. METHODS Thirty healthy volunteers were examined with a 3 T scanner. A RT-PC sequence was acquired at the first cervical level to quantify the flow rates of internal carotid arteries, internal jugular veins (IJVs) and CSF. Each RT-PC acquisition was repeated three times, while the subjects were asked to breathe in three different ways for 60 s each: freely (F), with a constant rate (PN) and with deep and constant respiration rate (PD). The average flow rates were computed, they were removed from the respective signals and integrated in the inspiratory and expiratory phases (differential volumes). Finally, the power spectral density was computed for each detrended flow rate. High- and very-high frequency peaks were identified on the spectra while their frequencies were compared to the respiratory and cardiac frequencies estimated using a thoracic belt and a pulse oximeter. The area under the spectra was computed in four 0.5 Hz-wide ranges, centered on the high-frequency peak, on very-high frequency peak and its 2nd and 3rd harmonics, and then they were normalized by the flow rate variance. The effect of breathing patterns on average flow rates, on systolic and diastolic peaks, and on the normalized power was tested. Finally, the differential volumes of inspiration were compared to those of expiration. RESULTS The frequencies of the high- and very-high spectral peaks corresponded to the respiratory and cardiac frequencies. The average flow rate progressively decreased from F to PN to PD breathing, and the cardiac modulations were less predominant especially for the IJVs. The respiratory modulation increased with PD breathing. The average volumes displaced in the inspiratory phases were not significantly different from those of the expiratory one. CONCLUSIONS The spectral analyses demonstrated higher respiratory modulations in PD compared to free breathing, even prevailing the cardiac modulation in the IJVs, showing an increment of the thoracic pump affecting the flow rate shape.
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Affiliation(s)
- Maria Marcella Laganà
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Sonia Di Tella
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy ,grid.8142.f0000 0001 0941 3192Department of Psychology, Università Cattolica del Sacro Cuore, Milan, Italy
| | - Francesca Ferrari
- grid.4643.50000 0004 1937 0327Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Laura Pelizzari
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Marta Cazzoli
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Noam Alperin
- grid.26790.3a0000 0004 1936 8606University of Miami, Miami, USA
| | - Ning Jin
- MR R&D Collaborations, Siemens Medical Solutions USA, Inc, Cleveland, OH USA
| | | | - Giuseppe Baselli
- grid.4643.50000 0004 1937 0327Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Francesca Baglio
- grid.418563.d0000 0001 1090 9021IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
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Abstract
PURPOSE OF REVIEW The aim of this study was to provide an overview on advances in intracranial pressure (ICP) protocols for care, moving from traditional to more recent concepts. RECENT FINDINGS Deep understanding of mechanics and dynamics of fluids and solids have been introduced for intracranial physiology. The amplitude or the harmonics of the cerebral-spinal fluid and the cerebral blood waves shows more information about ICP than just a numeric threshold. When the ICP overcome the compensatory mechanisms that maintain the compliance within the skull, an intracranial compartment syndrome (ICCS) is defined. Autoregulation monitoring emerge as critical tool to recognize CPP management. Measurement of brain tissue oxygen will be a critical intervention for diagnosing an ICCS. Surgical procedures focused on increasing the physiological compliance and increasing the volume of the compartments of the skull. SUMMARY ICP management is a complex task, moving far than numeric thresholds for activation of interventions. The interactions of intracranial elements requires new interpretations moving beyond classical theories. Most of the traditional clinical studies supporting ICP management are not generating high class evidence. Recommendations for ICP management requires better designed clinical studies using new concepts to generate interventions according to the new era of personalized medicine.
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12
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de Moraes FM, Rocha E, Barros FCD, Freitas FGR, Miranda M, Valiente RA, de Andrade JBC, Neto FEAC, Silva GS. Waveform Morphology as a Surrogate for ICP Monitoring: A Comparison Between an Invasive and a Noninvasive Method. Neurocrit Care 2022; 37:219-227. [PMID: 35332426 PMCID: PMC8947812 DOI: 10.1007/s12028-022-01477-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/22/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND Although the placement of an intraventricular catheter remains the gold standard technique for measuring intracranial pressure (ICP), the method has several limitations. Therefore, noninvasive alternatives to ICP (ICPni) measurement are of great interest. The main objective of this study was to compare the correlation and agreement of wave morphology between ICP (standard intraventricular ICP monitoring) and a new ICPni monitor in patients admitted with stroke. The second objective was to estimate the discrimination of the noninvasive method to detect intracranial hypertension. METHODS We prospectively collected data of adults admitted to an intensive care unit with subarachnoid hemorrhage, intracerebral hemorrhage, or ischemic stroke in whom an invasive ICP monitor was placed. Measurements were simultaneously collected from two parameters [time-to-peak (TTP) and the ratio regarding the second and first peak of the ICP wave (P2/P1 ratio)] of ICP and ICPni wave morphology monitors (Brain4care). Intracranial hypertension was defined as an invasively measured sustained ICP > 20 mm Hg for at least 5 min. RESULTS We studied 18 patients (subarachnoid hemorrhage = 14; intracerebral hemorrhage = 3; ischemic stroke = 1) on 60 occasions with a median age of 52 ± 14.3 years. A total of 197,400 waves (2495 min) from both ICP (standard ICP monitoring) and the ICPni monitor were sliced into 1-min-long segments, and we determined TTP and the P2/P1 ratio from the mean pulse. The median invasively measured ICP was 13 (9.8-16.2) mm Hg, and intracranial hypertension was present on 18 occasions (30%). The correlation and agreement between invasive and noninvasive methods for wave morphology were strong for the P2/P1 ratio and moderate for TTP using categoric (κ agreement 88.1% and 71.3%, respectively) and continuous (intraclass correlation coefficient 0.831 and 0.584, respectively) measures. There was a moderate but significant correlation with the mean ICP value (P2/P1 ratio r = 0.427; TTP r = 0.353; p < 0.001 for all) between noninvasive and invasive techniques. The areas under the curve to estimate intracranial hypertension were 0.786 [95% confidence interval (CI) 0.72-0.93] for the P2/P1 ratio and 0.694 (95% CI 0.60-0.74) for TTP. CONCLUSIONS The new ICPni wave morphology monitor showed a good agreement with the standard invasive method and an acceptable discriminatory power to detect intracranial hypertension. Clinical trial registration Trial registration: NCT05121155.
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Affiliation(s)
| | - Eva Rocha
- Neurology and Neurosurgery Department, Federal University of São Paulo, São Paulo, Brazil
| | | | | | - Maramelia Miranda
- Neurology and Neurosurgery Department, Federal University of São Paulo, São Paulo, Brazil
| | - Raul Alberto Valiente
- Neurology and Neurosurgery Department, Federal University of São Paulo, São Paulo, Brazil
| | | | | | - Gisele Sampaio Silva
- Neurology and Neurosurgery Department, Federal University of São Paulo, São Paulo, Brazil
- Hospital Israelita Albert Einstein, São Paulo, Brazil
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Ma L, He W, Li X, Liu X, Cao H, Guo L, Xiao X, Xu Y, Wu Y. Decreased CSF Dynamics in Treatment-Naive Patients with Essential Hypertension: A Study with Phase-Contrast Cine MR Imaging. AJNR Am J Neuroradiol 2021; 42:2146-2151. [PMID: 34620585 DOI: 10.3174/ajnr.a7284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 08/05/2021] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND PURPOSE Arterial sclerosis resulting from hypertension slows CSF transportation in the perivascular spaces, showing the intrinsic relationship between the CSF and the blood vasculature. However, the exact effect of hypertension on human CSF flow dynamics remains unclear. The present study aimed to evaluate CSF flow dynamics in treatment-naive patients with essential hypertension using phase-contrast cine MR imaging. MATERIALS AND METHODS The study included 60 never-treated patients with essential hypertension and 60 subjects without symptomatic atherosclerosis. CSF flow parameters, such as forward flow volume, forward peak velocity, reverse flow volume, reverse peak velocity, average flow, and net flow volume, were measured with phase-contrast cine MR imaging. Differences between the 2 groups were assessed to determine the independent determinants of these CSF flow parameters. RESULTS Forward flow volume, forward peak velocity, reverse flow volume, reverse peak velocity, and average flow in the patients with hypertension significantly decreased (all, P < .05). Increasing systolic blood pressure was significantly associated with lower forward flow volume (β = -0.44 mL/mL/mm Hg; 95% CI, -0.83 to -0.06 mL/mL/mm Hg), forward peak velocity (β = -0.50 cm/s/mm Hg; 95% CI, -0.88 to -0.12 cm/s/mm Hg), reverse flow volume (β = -0.61 mL/mL/mm Hg; 95% CI, -0.97 to -0.26 mL/mL/mm Hg), reverse peak velocity (β = -0.55 cm/s/mm Hg; 95% CI, -0.91-0.18 cm/s/mm Hg), and average flow (β = -0.50 mL/min/mm Hg; 95% CI, -0.93 to -0.08 mL/min/mm Hg). CONCLUSIONS The CSF flow dynamics in patients with hypertension are decreased, and increasing systolic blood pressure is strongly associated with lower CSF flow dynamics.
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Affiliation(s)
- L Ma
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - W He
- Department of Radiology (W.H.), Guangdong 999 Brain Hospital, Guangzhou, China
| | - X Li
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - X Liu
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - H Cao
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - L Guo
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - X Xiao
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Y Xu
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Y Wu
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
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14
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Pérez-Sánchez J, Carrillo de Gea JM, Rodríguez Barceló S, Toval Á, Fernández-Alemán JL, García-Berná JA, Popović M, Toval A. Intracranial pressure analysis software: A mapping study and proposal. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 209:106334. [PMID: 34450483 DOI: 10.1016/j.cmpb.2021.106334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 07/28/2021] [Indexed: 06/13/2023]
Abstract
Introduction Intracranial pressure (ICP) monitoring and analysis are techniques that are, each year, applied to millions of patients with pathologies with million of patients annually. The detection of the so called A and B-waves, and the analysis of subtle changes in C-waves, which are present in ICP waveform, may indicate decreased intracranial compliance, and may improve the clinical outcome. Despite the advances in the field of computerized data analysis, the visual screening of ICP continues to be the means principally employed to detect these waves. To the best of our knowledge, no review study has addressed automated ICP analysis in sufficient detail and a need to research the state of the art of ICP analysis has, therefore, been identified. Methodology This paper presents a systematic mapping study to provide answers to 7 research questions: publication time, venue and source trends, medical tasks undertaken, research methods used, computational systems developed, validation methodology, tools and systems employed for evaluation and research problems identified. An ICP software prototype is presented and evaluated as a consequence of the results. Results A total of 23 papers, published between 1990 and 2020, were selected from 6 online databases. After analyzing these papers, the following information was obtained: diagnosis and monitoring medical tasks were addressed to the same extent, and the main research method used was evaluation research. Several computational systems were identified in the papers, the main one being image classification, while the main analysis objective was single pulse analysis. Correlation with expert analysis was the most frequent validation method, and few of the papers stated the use of a published dataset. Few authors referred to the tools used to build or evaluate the proposed solutions. The most frequent research problem was the need for new analysis methods. These results have inspired us to propose a software prototype with which provide an automated solution that integrates ICP analysis and monitoring techniques. Conclusions The papers in this study were selected and classified with regard to ICP automated analysis methods. Several research gaps were identified, which the authors of this study have employed as a based on which to recommend future work. Furthermore, this study has identified the need for an empirical comparison between methods, which will require the use and development of certain standard metrics. An in-depth analysis conducted by means of systematic literature review is also required. The software prototype evaluation provided positive results, showing that the prototype may be a reliable system for A-wave detection.
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Affiliation(s)
- Juanjo Pérez-Sánchez
- Department of Informatics and Systems, Faculty of Computer Science, University of Murcia, Murcia, Spain.
| | - Juan M Carrillo de Gea
- Department of Informatics and Systems, Faculty of Computer Science, University of Murcia, Murcia, Spain.
| | | | - Ángel Toval
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain; Institute of Biomedical Research of Murcia, Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain.
| | - José L Fernández-Alemán
- Department of Informatics and Systems, Faculty of Computer Science, University of Murcia, Murcia, Spain.
| | - José A García-Berná
- Department of Informatics and Systems, Faculty of Computer Science, University of Murcia, Murcia, Spain.
| | - Miroljub Popović
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain; Institute of Biomedical Research of Murcia, Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain.
| | - Ambrosio Toval
- Department of Informatics and Systems, Faculty of Computer Science, University of Murcia, Murcia, Spain.
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15
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Kazimierska A, Kasprowicz M, Czosnyka M, Placek MM, Baledent O, Smielewski P, Czosnyka Z. Compliance of the cerebrospinal space: comparison of three methods. Acta Neurochir (Wien) 2021; 163:1979-1989. [PMID: 33852065 PMCID: PMC8195969 DOI: 10.1007/s00701-021-04834-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/26/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND Cerebrospinal compliance describes the ability of the cerebrospinal space to buffer changes in volume. Diminished compliance is associated with increased risk of potentially threatening increases in intracranial pressure (ICP) when changes in cerebrospinal volume occur. However, despite various methods of estimation proposed so far, compliance is seldom used in clinical practice. This study aimed to compare three measures of cerebrospinal compliance. METHODS ICP recordings from 36 normal-pressure hydrocephalus patients who underwent infusion tests with parallel recording of transcranial Doppler blood flow velocity were retrospectively analysed. Three methods were used to calculate compliance estimates during changes in the mean ICP induced by infusion of fluid into the cerebrospinal fluid space: (a) based on Marmarou's model of cerebrospinal fluid dynamics (CCSF), (b) based on the evaluation of changes in cerebral arterial blood volume (CCaBV), and (c) based on the amplitudes of peaks P1 and P2 of ICP pulse waveform (CP1/P2). RESULTS Increase in ICP caused a significant decrease in all compliance estimates (p < 0.0001). Time courses of compliance estimators were strongly positively correlated with each other (group-averaged Spearman correlation coefficients: 0.94 [0.88-0.97] for CCSF vs. CCaBV, 0.77 [0.63-0.91] for CCSF vs. CP1/P2, and 0.68 [0.48-0.91] for CCaBV vs. CP1/P2). CONCLUSIONS Indirect methods, CCaBV and CP1/P2, allow for the assessment of relative changes in cerebrospinal compliance and produce results exhibiting good correlation with the direct method of volumetric manipulation. This opens the possibility of monitoring relative changes in compliance continuously.
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Affiliation(s)
- Agnieszka Kazimierska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland.
| | - Magdalena Kasprowicz
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
- Institute of Electronic Systems, Faculty of Electronics and Information Technology, Warsaw University of Technology, Warsaw, Poland
| | - Michał M Placek
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
| | - Olivier Baledent
- Department of Medical Image Processing, CHU Amiens, University of Picardy Jules Verne, Amiens, France
| | - Peter Smielewski
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
| | - Zofia Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
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Hoiland RL, Griesdale DE, Sekhon MS. Invasive neuromonitoring post-cardiac arrest: Key considerations. Resuscitation 2021; 164:144-146. [PMID: 34000353 DOI: 10.1016/j.resuscitation.2021.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 05/07/2021] [Indexed: 11/30/2022]
Affiliation(s)
- Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada; Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, BC, Canada
| | - Donald E Griesdale
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada; Division of Critical Care Medicine, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
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17
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Lalou AD, Czosnyka M, Placek MM, Smielewski P, Nabbanja E, Czosnyka Z. CSF Dynamics for Shunt Prognostication and Revision in Normal Pressure Hydrocephalus. J Clin Med 2021; 10:jcm10081711. [PMID: 33921142 PMCID: PMC8071572 DOI: 10.3390/jcm10081711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Despite the quantitative information derived from testing of the CSF circulation, there is still no consensus on what the best approach could be in defining criteria for shunting and predicting response to CSF diversion in normal pressure hydrocephalus (NPH). OBJECTIVE We aimed to review the lessons learned from assessment of CSF dynamics in our center and summarize our findings to date. We have focused on reporting the objective perspective of CSF dynamics testing, without further inferences to individual patient management. DISCUSSION No single parameter from the CSF infusion study has so far been able to serve as an unquestionable outcome predictor. Resistance to CSF outflow (Rout) is an important biological marker of CSF circulation. It should not, however, be used as a single predictor for improvement after shunting. Testing of CSF dynamics provides information on hydrodynamic properties of the cerebrospinal compartment: the system which is being modified by a shunt. Our experience of nearly 30 years of studying CSF dynamics in patients requiring shunting and/or shunt revision, combined with all the recent progress made in producing evidence on the clinical utility of CSF dynamics, has led to reconsidering the relationship between CSF circulation testing and clinical improvement. CONCLUSIONS Despite many open questions and limitations, testing of CSF dynamics provides unique perspectives for the clinician. We have found value in understanding shunt function and potentially shunt response through shunt testing in vivo. In the absence of infusion tests, further methods that provide a clear description of the pre and post-shunting CSF circulation, and potentially cerebral blood flow, should be developed and adapted to the bed-space.
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Affiliation(s)
- Afroditi Despina Lalou
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (M.C.); (M.M.P.); (P.S.); (E.N.); (Z.C.)
- Correspondence: ; Tel.: +44-774-3567-585
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (M.C.); (M.M.P.); (P.S.); (E.N.); (Z.C.)
- Institute of Electronic Systems, Faculty of Electronics and Information Sciences, Warsaw University of Technology, 00-661 Warsaw, Poland
| | - Michal M. Placek
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (M.C.); (M.M.P.); (P.S.); (E.N.); (Z.C.)
| | - Peter Smielewski
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (M.C.); (M.M.P.); (P.S.); (E.N.); (Z.C.)
| | - Eva Nabbanja
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (M.C.); (M.M.P.); (P.S.); (E.N.); (Z.C.)
| | - Zofia Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (M.C.); (M.M.P.); (P.S.); (E.N.); (Z.C.)
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18
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Sylvain NJ, Salman MM, Pushie MJ, Hou H, Meher V, Herlo R, Peeling L, Kelly ME. The effects of trifluoperazine on brain edema, aquaporin-4 expression and metabolic markers during the acute phase of stroke using photothrombotic mouse model. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183573. [PMID: 33561476 DOI: 10.1016/j.bbamem.2021.183573] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/23/2021] [Accepted: 01/29/2021] [Indexed: 12/22/2022]
Abstract
Stroke is the second leading cause of death and the third leading cause of disability globally. Edema is a hallmark of stroke resulting from dysregulation of water homeostasis in the central nervous system (CNS) and plays the major role in stroke-associated morbidity and mortality. The overlap between cellular and vasogenic edema makes treating this condition complicated, and to date, there is no pathogenically oriented drug treatment for edema. Water balance in the brain is tightly regulated, primarily by aquaporin 4 (AQP4) channels, which are mainly expressed in perivascular astrocytic end-feet. Targeting AQP4 could be a useful therapeutic approach for treating brain edema; however, there is no approved drug for stroke treatment that can directly block AQP4. In this study, we demonstrate that the FDA-approved drug trifluoperazine (TFP) effectively reduces cerebral edema during the early acute phase in post-stroke mice using a photothrombotic stroke model. This effect was combined with an inhibition of AQP4 expression at gene and protein levels. Importantly, TFP does not appear to induce any deleterious changes on brain electrolytes or metabolic markers, including total protein or lipid levels. Our results support a possible role for TFP in providing a beneficial extra-osmotic effect on brain energy metabolism, as indicated by the increase of glycogen levels. We propose that targeting AQP4-mediated brain edema using TFP is a viable therapeutic strategy during the early and acute phase of stroke that can be further investigated during later stages to help in developing novel CNS edema therapies.
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Affiliation(s)
- Nicole J Sylvain
- Division of Neurosurgery, Department of Surgery, College of Medicine, University of Saskatchewan, Canada
| | - Mootaz M Salman
- Medical Sciences Division, Department of Physiology, Anatomy and Genetics, Oxford University, South Parks Road, Oxford OX1 3QX, UK.
| | - M Jake Pushie
- Division of Neurosurgery, Department of Surgery, College of Medicine, University of Saskatchewan, Canada
| | - Huishu Hou
- Division of Neurosurgery, Department of Surgery, College of Medicine, University of Saskatchewan, Canada
| | - Vedashree Meher
- Department of Anatomy and Cell Biology, College of Medicine University of Saskatchewan, Canada
| | - Rasmus Herlo
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Lissa Peeling
- Division of Neurosurgery, Department of Surgery, College of Medicine, University of Saskatchewan, Canada
| | - Michael E Kelly
- Division of Neurosurgery, Department of Surgery, College of Medicine, University of Saskatchewan, Canada
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19
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Ebert JJ, Varma H, Sisk RA. Unilateral Terson-Like Syndrome in a Patient With a Perinatal Ischemic Stroke. Ophthalmic Surg Lasers Imaging Retina 2020; 51:592-595. [PMID: 33104227 DOI: 10.3928/23258160-20201005-08] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/29/2020] [Indexed: 11/20/2022]
Abstract
Terson syndrome typically presents with bilateral hemorrhagic retinopathy associated with acute intracranial bleeding. The authors present a case of neonatal hemispheric ischemic stroke with vasogenic edema and increased intracranial pressure creating a unilateral Terson-like syndrome. Magnetic resonance imaging indicated congenital occlusion of the left internal carotid artery, among other vascular abnormalities. Chronic submacular, peripheral subretinal, and vitreous hemorrhage were observed, suggesting a multilaminar hemorrhagic process resembling Terson syndrome without frank intracranial hemorrhage. The patient underwent successful lens-sparing vitrectomy of the left eye. A unilateral Terson-like syndrome can result from severe cerebral edema following neonatal stroke in the setting of multiple congenital cerebrovascular abnormalities. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:592-595.].
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Pohlin F, Boustead KJ, Grace JF, Zeiler G. Isoflurane maintenance of neuroanaesthesia in two dogs with hydrocephalus and syringohydromyelia undergoing ventriculoperitoneal shunt surgery. VETERINARY RECORD CASE REPORTS 2020. [DOI: 10.1136/vetreccr-2020-001235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Friederike Pohlin
- Department of Companion Animal Clinical StudiesUniversity of PretoriaOnderstepoortSouth Africa
- Anaesthesia and Critical Care ServiceValley Farm Animal HospitalPretoriaSouth Africa
- Research Institute of Wildlife EcologyDepartment of Interdisciplinary Life SciencesUniversity of Veterinary Medicine ViennaViennaAustria
| | - Keagan John Boustead
- Department of Companion Animal Clinical StudiesUniversity of PretoriaOnderstepoortSouth Africa
- Anaesthesia and Critical Care ServiceValley Farm Animal HospitalPretoriaSouth Africa
| | - Justin Frederick Grace
- Department of Companion Animal Clinical StudiesUniversity of PretoriaOnderstepoortSouth Africa
- Anaesthesia and Critical Care ServiceValley Farm Animal HospitalPretoriaSouth Africa
| | - Gareth Zeiler
- Department of Companion Animal Clinical StudiesUniversity of PretoriaOnderstepoortSouth Africa
- Anaesthesia and Critical Care ServiceValley Farm Animal HospitalPretoriaSouth Africa
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Long-term monitoring of intracranial pressure in freely-moving rats; impact of different physiological states. Fluids Barriers CNS 2020; 17:39. [PMID: 32517699 PMCID: PMC7285467 DOI: 10.1186/s12987-020-00199-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 05/27/2020] [Indexed: 12/17/2022] Open
Abstract
Background Elevated intracranial pressure (ICP) is observed in association with a range of brain disorders. There is limited insight into the regulatory mechanisms of ICP under physiological conditions, and consequently also under pathological conditions. Thereby, to understand the mechanisms underlying ICP dynamics, precise, valid and long-term ICP recordings are of importance in the preclinical setting. Herein, we used a novel telemetric system for ICP recordings which allowed for long-term recordings in freely-moving rats. The aim was to investigate ICP dynamics under different physiological states and investigate how factors such as surgery/recovery, body position, light–dark, co-housing, weight and anesthesia may influence ICP and its waveforms. Methods A telemetric device was implanted epidurally in rats and signals were recorded continuously for up to 50 days (n = 14). Recording was divided into three experimental periods: a surgical recovery period (RP), a physiological period (PP) and an experimental period (EP). Histology was performed to study the morphology of implanted rats and non-implanted rats (n = 17). Results For the first time, we can demonstrate continuous ICP recordings in freely-moving and co-housed rats for up to 50 days with a high degree of stability. The mean ICP in the recording periods were; RP: 3.2 ± 0.6 mmHg, PP: 5.0 ± 0.6 mmHg and EP: 4.7 ± 0.6 mmHg. In the RP, the ICP was significantly lower compared to the PP (P = 0.0034). Significant light–dark difference in ICP with 21% increase in respiratory slow-wave amplitude was observed in the co-housed animals but not in single-housed animals. The ICP signal was raised during the dark period relative to the light (Δ0.3 ± 0.07 mmHg, P = 0.0043). Administration of anesthesia gave a short-term increase in ICP followed by a significant decrease in ICP. No signs of tissue damage or inflammation were found in the implanted brains. Conclusions ICP dynamics were influenced by several factors such as, use of anesthesia, light–dark difference and housing conditions. Our study demonstrates the importance of performing ICP physiological measurements in freely-moving animals. This has significant implications for moving the preclinical research field forward in order to properly study ICP physiology during disease development and to explore drug targets for alleviating increased ICP.
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Annese V, Frau C, Murdeu N, Gregorio M, Sanguigni S. Cerebral venous congestion correlates to acute aneurysm rupture: An illustrative case with Doppler ultrasonography study. eNeurologicalSci 2020; 19:100231. [PMID: 32181376 PMCID: PMC7066058 DOI: 10.1016/j.ensci.2020.100231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 01/01/2020] [Accepted: 02/17/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The objective of our description is to shed light on some new hemodynamic and clinical characteristics in the unstable cerebral aneurysm Case: We describe a 54 year old woman who presented a tension headache, that increasing for several days. A CT scan performed in ER suggests a possible arterial ectasia at the level of the circle of Willis. The patient is hospitalized. An angio CT shows an aneurysm of the anterior communicating artery, without signs of fixation and/or other instability. A subsequent TCCD examination with venous study shows clear congestion at the level of the spheno-parietal sinus. The Valsalva maneuver determines an increase in local congestion. In the light of the ultrasound picture, the patient was quickly received in Neurosurgery with success. CONCLUSION we describe a clinical case where the worsening tension headache was not secondary to the increase of volume of the aneurysm but was an epiphenomenon of venous congestion, explored with TCCD. The mass effect of the aneurysm determined venous sinus compression and changed the hemodynamic of the cerebral venous flow. We believe that venous outflow obstruction and a high intracranial venous pressure gradient may be a cerebral aneurysm rupture factor.
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Affiliation(s)
- Virginia Annese
- UOC of Neurology, Hospital Legnago, ULSS 9 Scaligera - Verona, Italy
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Eftekhari S, Westgate CSJ, Uldall MS, Jensen RH. Preclinical update on regulation of intracranial pressure in relation to idiopathic intracranial hypertension. Fluids Barriers CNS 2019; 16:35. [PMID: 31767019 PMCID: PMC6878629 DOI: 10.1186/s12987-019-0155-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 11/13/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Elevated intracranial pressure (ICP) is observed in association with a range of brain disorders. One of these challenging disorders is idiopathic intracranial hypertension (IIH), characterized by raised ICP of unknown cause with significant morbidity and limited therapeutic options. In this review, special focus is put on the preclinical research performed in order to understand the pathophysiology behind ICP regulation and IIH. This includes cerebrospinal fluid dynamics, molecular mechanisms underlying disturbances in brain fluids leading to elevated ICP, role of obesity in IIH, development of an IIH model and ICP measurements in rodents. The review also discusses existing and new drug targets for IIH that have been evaluated in vivo. CONCLUSIONS ICP monitoring in rodents is challenging and different methods have been applied. Some of these methods are invasive, depend on use of anesthesia and only allow short-term monitoring. Long-term ICP recordings are needed to study IIH but existing methods are hampered by several limitations. As obesity is one of the most common risk factors for IIH, a rodent obese model has been developed that mimics some key aspects of IIH. The most commonly used drugs for IIH have been evaluated in vivo for their efficacy at lowering ICP in the existing animal models. These studies suggest these drugs, including acetazolamide, might have limited or no reducing effect on ICP. Two drug targets that can impact ICP in healthy rodents are topiramate and a glucagon-like peptide-1 receptor (GLP-1R) agonist. However, it remains to evaluate their effect in an IIH model with more precise and valid ICP monitoring system. Therefore, continued evaluation in the preclinical research with refined tools is of great importance to further understand the pathophysiology behind disorders with raised ICP and to explore new drug targets.
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Affiliation(s)
- Sajedeh Eftekhari
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
| | - Connar Stanley James Westgate
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
| | - Maria Schmidt Uldall
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
| | - Rigmor Hoejland Jensen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
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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: 17] [Impact Index Per Article: 3.4] [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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From decompressive craniectomy to cranioplasty and beyond-a pediatric neurosurgery perspective. Childs Nerv Syst 2019; 35:1517-1524. [PMID: 31327037 DOI: 10.1007/s00381-019-04303-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/08/2019] [Indexed: 01/05/2023]
Abstract
PURPOSE Decompressive craniectomy (DC) is an established neurosurgical emergency technique. Patient selection, optimal timing, and technical aspects related to DC and subsequent cranioplasty remain subjects of debate. For children, the overall degree of evidence is low, compared with randomized controlled trials (RCTs) in adults. METHODS Here, we present a detailed retrospective analysis of pediatric DC, covering the primary procedure and cranioplasty. Results are analyzed and discussed in the light of modern scientific evidence, and conclusions are drawn to stimulate future research. RESULTS The main indication for DC in children is traumatic brain injury (TBI). Primary and secondary DC is performed with similar frequency. Outcome appears to be better than that in adults, although long-term complications (especially bone flap resorption after autologous cranioplasty) are more common in children. Overt clinical signs of cerebral herniation prior to DC are predictors of poor outcome. CONCLUSIONS We conclude that DC is an important option in the armamentarium to treat life-threatening intracranial hypertension, but further research is warranted, preferentially in a multicenter prospective registry.
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Sekhon MS, Griesdale DE, Ainslie PN, Gooderham P, Foster D, Czosnyka M, Robba C, Cardim D. Intracranial pressure and compliance in hypoxic ischemic brain injury patients after cardiac arrest. Resuscitation 2019; 141:96-103. [PMID: 31185256 DOI: 10.1016/j.resuscitation.2019.05.036] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/17/2019] [Accepted: 05/29/2019] [Indexed: 02/06/2023]
Abstract
INTRODUCTION In hypoxic ischemic brain injury (HIBI), increased intracranial pressure (ICP) can ensue from cerebral edema stemming from cytotoxic and vasogenic mechanisms. Downstream sequelae of restricted cerebral blood flow lead to neurologic braindeath. There is limited data characterizing the temporal trends and patterns of ICP and compliance in human HIBI patients. METHODS Patients underwent invasive ICP monitoring with a parenchymal probe (Camino) and were managed with a tier-based management algorithm for elevated ICP. Data pertaining to mean arterial pressure (MAP), ICP, brain tissue oxygenation (PbtO2), end tidal carbon dioxide (ETCO2), core body temperature and RAP (moving correlation coefficient between mean ICP and its mean pulse amplitude) as a measure of intracranial compliance were recorded in the ICM + software. Data pertaining to ICP lowering interventions was also collected. RESULTS Ten patients were included with a median age of 47 (range 20-71) and seven were male (7/10). The mean ICP was 14 mmHg (SD 11) and time of ICP> 20 mmHg was 22% (range 0-100). The mean MAP, ETCO2 and temperature were 89 mmHg (SD 13), 31 mmHg (SD 7), 35.7 °C (SD 0.9), respectively. The mean RAP was 0.58 (SD 0.34) and time of RAP > 0.4 was 78% (range 57-97). There were no significant relationships between ETCO2 and temperature with ICP. CONCLUSIONS In our cohort, HIBI was characterized by normal ICP but with limited intracranial compliance. However, significant in between patient heterogeneity exists with respect to temporal patterns of intracranial pressure - volume relationships in HIBI. TRIAL REGISTRATION clinicaltrials.gov (NCT03609333).
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Affiliation(s)
- Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada.
| | - Donald E Griesdale
- Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada; Department of Anaesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada; Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, 899 West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada
| | - Philip N Ainslie
- Department of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, BC, Canada
| | - Peter Gooderham
- Division of Neurosurgery, Department of Surgery, Vancouver General Hospital, West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M96, Canada
| | - Denise Foster
- Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada
| | - Marek Czosnyka
- Department of Clinical Neurosciences, Division of Neurosurgery, Addenbrookes Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Chiara Robba
- Department of Clinical Neurosciences, Division of Neurosurgery, Addenbrookes Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Danilo Cardim
- Department of Anaesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada
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Nursing Care in ICU. CONGENIT HEART DIS 2019. [DOI: 10.1007/978-3-319-78423-6_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Uryga A, Kasprowicz M, Burzyńska M, Calviello L, Kaczmarska K, Czosnyka M. Cerebral arterial time constant calculated from the middle and posterior cerebral arteries in healthy subjects. J Clin Monit Comput 2018; 33:605-613. [PMID: 30291539 DOI: 10.1007/s10877-018-0207-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/01/2018] [Indexed: 10/28/2022]
Abstract
The cerebral arterial blood volume changes (∆CaBV) during a single cardiac cycle can be estimated using transcranial Doppler ultrasonography (TCD) by assuming pulsatile blood inflow, constant, and pulsatile flow forward from large cerebral arteries to resistive arterioles [continuous flow forward (CFF) and pulsatile flow forward (PFF)]. In this way, two alternative methods of cerebral arterial compliance (Ca) estimation are possible. Recently, we proposed a TCD-derived index, named the time constant of the cerebral arterial bed (τ), which is a product of Ca and cerebrovascular resistance and is independent of the diameter of the insonated vessel. In this study, we aim to examine whether the τ estimated by either the CFF or the PFF model differs when calculated from the middle cerebral artery (MCA) and the posterior cerebral artery (PCA). The arterial blood pressure and TCD cerebral blood flow velocity (CBFVa) in the MCA and in the PCA were non-invasively measured in 32 young, healthy volunteers (median age: 24, minimum age: 18, maximum age: 31). The τ was calculated using both the PFF and CFF models from the MCA and the PCA and compared using a non-parametric Wilcoxon signed-rank test. Results are presented as medians (25th-75th percentiles). The cerebrovascular time constant estimated in both arteries using the PFF model was shorter than when using the CFF model (ms): [64.83 (41.22-104.93) vs. 178.60 (160.40-216.70), p < 0.001 in the MCA, and 44.04 (17.15-81.17) vs. 183.50 (153.65-204.10), p < 0.001 in the PCA, respectively]. The τ obtained using the PFF model was significantly longer from the MCA than from the PCA, p = 0.004. No difference was found in the τ when calculated using the CFF model. Longer τ from the MCA might be related to the higher Ca of the MCA than that of the PCA. Our results demonstrate MCA-PCA differences in the τ, but only when the PFF model was applied.
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Affiliation(s)
- Agnieszka Uryga
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370, Wrocław, Poland.
| | - Magdalena Kasprowicz
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370, Wrocław, Poland
| | - Małgorzata Burzyńska
- Department of Anesthesiology and Intensive Care, Wroclaw Medical University, Wrocław, Poland
| | - Leanne Calviello
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Katarzyna Kaczmarska
- Department of Neurosurgery, Mossakowski Medical Research Centre Polish Academy of Sciences, Warsaw, Poland.,Institute of Electronic Systems, Faculty of Electronics and Information Technology, Warsaw University of Technology, Warsaw, Poland
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Institute of Electronic Systems, Faculty of Electronics and Information Technology, Warsaw University of Technology, Warsaw, Poland
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Pineda B, Kosinski C, Kim N, Danish S, Craelius W. Assessing Cerebral Hemodynamic Stability After Brain Injury. ACTA NEUROCHIRURGICA. SUPPLEMENT 2018; 126:297-301. [PMID: 29492578 DOI: 10.1007/978-3-319-65798-1_58] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
OBJECTIVE Following brain injury, unstable cerebral hemodynamics can be characterized by abnormal rises in intracranial pressure (ICP). This behavior has been quantified by the RAP index: the correlation (R) between ICP pulse amplitude (A) and mean (P). While RAP could be a valuable indicator of autoregulatory processes, its prognostic ability is not well established and its validity has been questioned due to potential errors in measurement. Here, we test (1) whether RAP is a consistent measure of intracranial hemodynamics and (2) whether RAP has prognostic value in predicting hemodynamic instability following brain injury. MATERIALS AND METHODS RAP was tested in seven brain injured patients treated in a surgical intensive care unit. A sample of ICP data was randomly chosen and segmented into 1 hour periods. Hours were then categorized as either stable, which contained no sharp rises in ICP, or unstable, which contained ≥1 sharp rise-where a sharp rise is defined as ICP exceeding a mean slope of 0.15 mmHg/s. Equal numbers of stable and unstable segments were then selected for each patient. RAP was calculated as the Pearson's correlation coefficient between ICP pulse amplitude (AMP) and mean (mICP), determined in 6 second windows, according to established methods. RESULTS Results showed that (1) average AMP and ICP levels were similar between stable and unstable periods and (2) unstable periods were identified by RAP values exceeding 0.6 with an average positive predictive value of 74%. CONCLUSIONS We conclude that RAP can provide a valid measure of ICP dynamics, is not affected by sensor drift, and can better distinguish periods of instability than ICP or AMP alone.
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Affiliation(s)
- Bianca Pineda
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Colin Kosinski
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Nam Kim
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Shabbar Danish
- Department of Neurosurgery, Rutgers, Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - William Craelius
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
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Habboub G, Sharma M, Barnett GH, Mohammadi AM. A novel combination of two minimally invasive surgical techniques in the management of refractory radiation necrosis: Technical note. J Clin Neurosci 2017; 35:117-121. [DOI: 10.1016/j.jocn.2016.09.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 09/26/2016] [Indexed: 11/25/2022]
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Jeong JH. The Pathophysiology of Brain Edema and Intracranial Hypertension. JOURNAL OF NEUROCRITICAL CARE 2016. [DOI: 10.18700/jnc.160090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Winkler EA, Minter D, Yue JK, Manley GT. Cerebral Edema in Traumatic Brain Injury. Neurosurg Clin N Am 2016; 27:473-88. [DOI: 10.1016/j.nec.2016.05.008] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Abstract
PURPOSE OF REVIEW Intracranial pressure (ICP) can be elevated in traumatic brain injury, large artery acute ischemic stroke, intracranial hemorrhage, intracranial neoplasms, and diffuse cerebral disorders such as meningitis, encephalitis, and acute hepatic failure. Raised ICP is also known as intracranial hypertension and is defined as a sustained ICP of greater than 20 mm Hg. RECENT FINDINGS ICP must be measured through an invasive brain catheter, typically an external ventricular catheter that can drain CSF and measure ICP, or through an intraparenchymal ICP probe. Proper recognition of the clinical signs of elevated ICP is essential for timely diagnosis and treatment to prevent cerebral hypoperfusion and possible brain death. Clinical signs of elevated ICP include headache, papilledema, nausea, and vomiting in the early phases, followed by stupor and coma, pupillary changes, hemiparesis or quadriparesis, posturing and respiratory abnormalities, and eventually cardiopulmonary arrest. SUMMARY Management of elevated ICP is, in part, dependent on the underlying cause. Medical options for treating elevated ICP include head of bed elevation, IV mannitol, hypertonic saline, transient hyperventilation, barbiturates, and, if ICP remains refractory, sedation, endotracheal intubation, mechanical ventilation, and neuromuscular paralysis. Surgical options include CSF drainage if hydrocephalus is present and decompression of a surgical lesion, such as an intracranial hematoma/large infarct or tumor, if the patient's condition is deemed salvageable. Future research should continue investigating medical and surgical options for the treatment of raised ICP, such as hypothermia, drugs that reduce cerebral edema, and operations aimed at reducing intracranial mass effect.
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Eide PK. The correlation between pulsatile intracranial pressure and indices of intracranial pressure-volume reserve capacity: results from ventricular infusion testing. J Neurosurg 2016; 125:1493-1503. [PMID: 26918478 DOI: 10.3171/2015.11.jns151529] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The objective of this study was to examine how pulsatile and static intracranial pressure (ICP) scores correlate with indices of intracranial pressure-volume reserve capacity, i.e., intracranial elastance (ICE) and intracranial compliance (ICC), as determined during ventricular infusion testing. METHODS All patients undergoing ventricular infusion testing and overnight ICP monitoring during the 6-year period from 2007 to 2012 were included in the study. Clinical data were retrieved from a quality registry, and the ventricular infusion pressure data and ICP scores were retrieved from a pressure database. The ICE and ICC (= 1/ICE) were computed during the infusion phase of the infusion test. RESULTS During the period from 2007 to 2012, 82 patients with possible treatment-dependent hydrocephalus underwent ventricular infusion testing within the department of neurosurgery. The infusion tests revealed a highly significant positive correlation between ICE and the pulsatile ICP scores mean wave amplitude (MWA) and rise-time coefficient (RTC), and the static ICP score mean ICP. The ICE was negatively associated with linear measures of ventricular size. The overnight ICP recordings revealed significantly increased MWA (> 4 mm Hg) and RTC (> 20 mm Hg/sec) values in patients with impaired ICC (< 0.5 ml/mm Hg). CONCLUSIONS In this study cohort, there was a significant positive correlation between pulsatile ICP and ICE measured during ventricular infusion testing. In patients with impaired ICC during infusion testing (ICC < 0.5 ml/mm Hg), overnight ICP recordings showed increased pulsatile ICP (MWA > 4 mm Hg, RTC > 20 mm Hg/sec), but not increased mean ICP (< 10-15 mm Hg). The present data support the assumption that pulsatile ICP (MWA and RTC) may serve as substitute markers of pressure-volume reserve capacity, i.e., ICE and ICC.
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Affiliation(s)
- Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital-Rikshospitalet, and Faculty of Medicine, University of Oslo, Norway
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Lee HJ, Jeong EJ, Kim H, Czosnyka M, Kim DJ. Morphological Feature Extraction From a Continuous Intracranial Pressure Pulse via a Peak Clustering Algorithm. IEEE Trans Biomed Eng 2015; 63:2169-76. [PMID: 26841386 DOI: 10.1109/tbme.2015.2512278] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE An increase in intracranial pressure (ICP) is frequently observed in patients with severe traumatic brain injury (TBI). The information derived from the observation of temporal changes in the mean ICP is insufficient for assessment of the compensatory reserve of the injured brain. This assessment can be achieved via continuous morphological analysis of the pulse waveform of the ICP. METHODS Continuous arterial blood pressure (ABP) and ICP recordings from 292 TBI patients were analyzed. The algorithm extracted morphological landmarks (peaks, troughs, and flats) from the ICP. Among the extracted peaks, P1, P2, and P3 were assigned through peak clustering. The performance of the proposed method was validated through a comparison of the algorithm-defined peaks and those manually identified by experienced observers. RESULTS The proposed algorithm successfully identified the three distinguishing peaks of the ICP with satisfactory accuracy (95.3%, 87.8%, and 87.5% for P1, P2, and P3, respectively), even from minimally filtered raw signals. CONCLUSION The algorithm extracted the morphological features from both ABP and ICP recordings with high accuracy. SIGNIFICANCE The ABP and ICP pulse waveforms can be simultaneously analyzed in real time using the proposed algorithm. The morphological features from these signals may aid the continuous care of patients with TBI.
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Tommasino N, Forteza D, Godino M, Mizraji R, Álvarez I. A Model to Predict Progression in Brain-Injured Patients. Transplant Proc 2014; 46:2950-2. [DOI: 10.1016/j.transproceed.2014.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Macintyre I. A hotbed of medical innovation: George Kellie (1770-1829), his colleagues at Leith and the Monro-Kellie doctrine. JOURNAL OF MEDICAL BIOGRAPHY 2014; 22:93-100. [PMID: 24585579 DOI: 10.1177/0967772013479271] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The Monro-Kellie doctrine is named after two Scottish doctors, the well-known Alexander Monro secundus and George Kellie, whose life and work has not previously been described in detail. After service as a naval surgeon, Kellie followed his father into a career as a surgeon in the port of Leith, near Edinburgh. His publications show him to be a compassionate and observant doctor, ready to question established concepts. He worked closely with surgical colleagues in the town, some of whom made important contributions in their own right. The paper which led to eponymous fame was based on post-mortem observations on the volume of blood in the cerebral blood vessels, which led him to conclude that a change in volume of one intracranial constituent must be compensated by a reciprocal change in the others. He collaborated with Monro in this work but the doctrine was disseminated by another colleague, John Abercrombie, in his widely read book on neuropathology. Kellie achieved recognition within the local medical community. The doctrine which bears his name remains fundamental to our understanding of pressure and volume relationships within the cranium.
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Andrade AFD, Soares MS, Patriota GC, Belon AR, Paiva WS, Bor-Seng-Shu E, Oliveira MDL, Nascimento CN, Noleto GS, Alves Junior AC, Figueiredo EG, Otoch JP, Teixeira MJ. Experimental model of intracranial hypertension with continuous multiparametric monitoring in swine. ARQUIVOS DE NEURO-PSIQUIATRIA 2013; 71:802-6. [DOI: 10.1590/0004-282x20130126] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/31/2013] [Indexed: 11/21/2022]
Abstract
Objective Intracranial hypertension (IH) develops in approximately 50% of all patients with severe traumatic brain injury (TBI). Therefore, it is very important to identify a suitable animal model to study and understand the pathophysiology of refractory IH to develop effective treatments. Methods We describe a new experimental porcine model designed to simulate expansive brain hematoma causing IH. Under anesthesia, IH was simulated with a balloon insufflation. The IH variables were measured with intracranial pressure (ICP) parenchymal monitoring, epidural, cerebral oximetry, and transcranial Doppler (TCD). Results None of the animals died during the experiment. The ICP epidural showed a slower rise compared with parenchymal ICP. We found a correlation between ICP and cerebral oximetry. Conclusion The model described here seems useful to understand some of the pathophysiological characteristics of acute IH.
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Hu X, Gonzalez N, Bergsneider M. Steady-state indicators of the intracranial pressure dynamic system using geodesic distance of the ICP pulse waveform. Physiol Meas 2012; 33:2017-31. [PMID: 23151442 DOI: 10.1088/0967-3334/33/12/2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Normal functioning of the brain depends on the homeostasis (∼ steady state) of its various physiological sub-systems, one of which is the intracranial pressure (ICP) dynamic system. The ICP dynamic system of an injured brain is susceptible to various acute changes that should ideally be detected by ICP monitoring even for comatose patients. However, the status quo of ICP monitoring solely targets mean ICP. We aimed to demonstrate a novel approach to detect acute deviation from steady state of an ICP dynamic system in an absence of significant mean ICP changes. We hypothesized that steady state of ICP dynamic systems is reflected as ICP pulses of similar mean ICP levels resembling each other for a given subject. A general framework was used to derive such a steady-state indicator that can accommodate different metrics of inter-pulse distance and different statistics of the distance histograms. In addition to conventional Euclidean distance and Pearson correlation, geodesic distance between pulses was introduced as a novel metric. These different ways of calculating steady-state indicators under the proposed framework were evaluated on three types of continuous ICP recordings: (1) those between two consecutive brain imaging studies that demonstrated acute ventricular enlargement for slit ventricle syndrome (SVS) patients undergoing a trial of shunt externalization and clamping (SVS+); (2) those between consecutive brain imaging studies from the SVS patients under the same trial but without ventricular enlargement (SVS-); (3) overnight recordings from normal pressure hydrocephalus (NPH) patients. It was observed that only the standard deviation of geodesic distance correctly differentiated between SVS+ and SVS- and between SVS+ and NPH while avoiding discriminating between SVS- and NPH. It was also found that 45% SVS+ cases had a multimodal geodesic distance histogram while none of SVS- and 3.8% of NPH cases had such a multimodal histogram. Pulses with a large number of distant pulses for the five multimodal-histogram SVS+ cases fell in short time windows indicating that acute ventricular changes may have occurred in these confined time windows during which no significant changes of mean ICP were observed. In contrast, the pulses with a large number of distant pulses for the two multimodal-histogram NPH cases did not cluster temporally. In conclusion, the geodesic inter-pulse distance is a promising metric to quantify distance intrinsic to the underneath geometric structure of ICP signals and hence is a more suitable way to derive a steady-state indicator of an ICP dynamic system.
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Affiliation(s)
- Xiao Hu
- Neural Systems and Dynamics Laboratory, Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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