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Das N, Dhamija R, Sarkar S. The role of astrocytes in the glymphatic network: a narrative review. Metab Brain Dis 2024; 39:453-465. [PMID: 38008886 DOI: 10.1007/s11011-023-01327-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 11/17/2023] [Indexed: 11/28/2023]
Abstract
To date, treatment of Central Nervous System (CNS) pathology has largely focused on neuronal structure and function. Yet, revived attention towards fluid circulation within the CNS has exposed the need to further explore the role of glial cells in maintaining homeostasis within neural networks. In the past decade, discovery of the neural glymphatic network has revolutionized traditional understanding of fluid dynamics within the CNS. Advancements in neuroimaging have revealed alternative pathways of cerebrospinal fluid (CSF) generation and efflux. Here, we discuss emerging perspectives on the role of astrocytes in CSF hydrodynamics, with particular focus on the contribution of aquaporin-4 channels to the glymphatic network. Astrocytic structural features and expression patterns are detailed in relation to their function in maintaining integrity of the Blood Brain Barrier (BBB) as part of the neurovascular unit (NVU). This narrative also highlights the potential role of glial dysfunction in pathogenesis of neurodegenerative disease, hydrocephalus, intracranial hemorrhage, ischemic stroke, and traumatic brain injury. The purpose of this literature summary is to provide an update on the changing landscape of scientific theory surrounding production, flow, and absorption of cerebrospinal fluid. The overarching aim of this narrative review is to advance the conception of basic, translational, and clinical research endeavors investigating glia as therapeutic targets for neurological disease.
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Affiliation(s)
- Nikita Das
- Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Ravi Dhamija
- Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Sumit Sarkar
- Division of Neurotoxicology, HFT-132, National Center for Toxicological Research, U.S. Food & Drug Administration, Jefferson, AR, 72079, USA.
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Bateman GA, Bateman AR. The dilated veins surrounding the cord in multiple sclerosis suggest elevated pressure and obstruction of the glymphatic system. Neuroimage 2024; 286:120517. [PMID: 38211705 DOI: 10.1016/j.neuroimage.2024.120517] [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: 11/22/2023] [Revised: 01/07/2024] [Accepted: 01/09/2024] [Indexed: 01/13/2024] Open
Abstract
Recently, Clarke et al. published a study using spinal cord susceptibility weighted imaging in multiple sclerosis patients at 7T. They discovered dilated intradural extramedullary veins surrounding the cord. The purpose of this commentary is to point out some recent research by our group, which suggests this dilatation also occurs in the bridging cortical veins surrounding the brain. The dilatation indicates a focal elevation in the venous pressure secondary to impedance mismatching. Due to the shared outflow geometry, dilatation of the outflow veins will obstruct the glymphatic pathway of the spinal cord altering the immune response.
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Affiliation(s)
- Grant A Bateman
- Department of Medical Imaging, John Hunter Hospital, Newcastle, NSW, Australia; Newcastle University Faculty of Health, Callaghan Campus, Newcastle, NSW, Australia.
| | - Alexander R Bateman
- School of Mechanical Engineering, University of New South Wales, Sydney, NSW, Australia
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Nozaleda GL, Alaminos-Quesada J, Coenen W, Haughton V, Sánchez AL. An analytic model for the flow induced in syringomyelia cavities. JOURNAL OF FLUID MECHANICS 2024; 978:A22. [PMID: 38746046 PMCID: PMC11089288 DOI: 10.1017/jfm.2023.1018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
A simple two-dimensional fluid-structure-interaction problem, involving viscous oscillatory flow in a channel separated by an elastic membrane from a fluid-filled slender cavity, is analyzed to shed light on the flow dynamics pertaining to syringomyelia, a neurological disorder characterized by the appearance of a large tubular cavity (syrinx) within the spinal cord. The focus is on configurations in which the velocity induced in the cavity, representing the syrinx, is comparable to that found in the channel, representing the subarachnoid space surrounding the spinal cord, both flows being coupled through a linear elastic equation describing the membrane deformation. An asymptotic analysis for small stroke lengths leads to closed-form expressions for the leading-order oscillatory flow, and also for the stationary flow associated with the first-order corrections, the latter involving a steady distribution of transmembrane pressure. The magnitude of the induced flow is found to depend strongly on the frequency, with the result that for channel flow rates of non-sinusoidal waveform, as those found in the spinal canal, higher harmonics can dominate the sloshing motion in the cavity, in agreement with previous in vivo observations. Under some conditions, the cycle-averaged transmembrane pressure, also showing a marked dependence on the frequency, changes sign on increasing the cavity transverse dimension (i.e. orthogonal to the cord axis), underscoring the importance of cavity size in connection with the underlying hydrodynamics. The analytic results presented here can be instrumental in guiding future numerical investigations, needed to clarify the pathogenesis of syringomyelia cavities.
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Affiliation(s)
- G. L. Nozaleda
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093-0411, USA
| | - J. Alaminos-Quesada
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093-0411, USA
| | - W. Coenen
- Grupo de Mecánica de Fluidos, Universidad Carlos III de Madrid, Leganés, 28911 Spain
| | - V. Haughton
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706 USA
| | - A. L. Sánchez
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093-0411, USA
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Bateman GA, Bateman AR. The dilated cortical veins found in multiple sclerosis can explain the reduction in glymphatic flow. Mult Scler Relat Disord 2024; 81:105136. [PMID: 37979409 DOI: 10.1016/j.msard.2023.105136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/11/2023] [Accepted: 11/12/2023] [Indexed: 11/20/2023]
Affiliation(s)
- Grant A Bateman
- Department of Medical Imaging, John Hunter Hospital, Newcastle, NSW, Australia; Faculty of Health, Newcastle University, Callaghan Campus, Newcastle, NSW, Australia.
| | - Alexander R Bateman
- School of Mechanical Engineering, University of New South Wales, Sydney, NSW, Australia
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Taylor Z, English C, Cramberg M, Young BA. The influence of spinal venous blood pressure on cerebrospinal fluid pressure. Sci Rep 2023; 13:20989. [PMID: 38017027 PMCID: PMC10684553 DOI: 10.1038/s41598-023-48334-8] [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: 08/01/2023] [Accepted: 11/25/2023] [Indexed: 11/30/2023] Open
Abstract
In Alligator mississippiensis the spinal dura is surrounded by a venous sinus; pressure waves can propagate in the spinal venous blood, and these spinal venous pressures can be transmitted to the spinal cerebrospinal fluid (CSF). This study was designed to explore pressure transfer between the spinal venous blood and the spinal CSF. At rest the cardiac-related CSF pulsations are attenuated and delayed, while the ventilatory-related pulsations are amplified as they move from the spinal venous blood to the spinal CSF. Orthostatic gradients resulted in significant alterations of both cardiac- and ventilatory-related CSF pulsations. Manual lateral oscillations of the alligator's tail created pressure waves in the spinal CSF that propagated, with slight attenuation but no delay, to the cranial CSF. Oscillatory pressure pulsations in the spinal CSF and venous blood had little influence on the underlying ventilatory pulsations, though the same oscillatory pulsations reduced the ventilatory- and increased the cardiac-related pulsations in the cranial CSF. In Alligator the spinal venous anatomy creates a more complex pressure relationship between the venous and CSF systems than has been described in humans.
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Affiliation(s)
- Z Taylor
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, MO, 63501, USA
| | - C English
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, MO, 63501, USA
| | - M Cramberg
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, MO, 63501, USA
| | - B A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, MO, 63501, USA.
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Bateman GA, Bateman AR. Syringomyelia Is Associated with a Reduction in Spinal Canal Compliance, Venous Outflow Dilatation and Glymphatic Fluid Obstruction. J Clin Med 2023; 12:6646. [PMID: 37892782 PMCID: PMC10607592 DOI: 10.3390/jcm12206646] [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: 09/26/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023] Open
Abstract
The cause of the cystic dilatation of the cord found in syringomyelia has been a source of conjecture for a considerable time. Recent studies have shown that there is a reduction in craniospinal compliance in both childhood hydrocephalus and multiple sclerosis which leads to venous outflow dilatation. Both diseases are associated with glymphatic outflow obstruction. Venous dilatation will narrow the perivenous glymphatic outflow pathway and lead to an increase in glymphatic outflow resistance. Syringomyelia has been shown to be associated with reduced spinal canal compliance. This paper discusses the possibility that venous dilatation and obstructed glymphatic outflow within the cord may be behind the cystic dilatation found within syringomyelia.
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Affiliation(s)
- Grant Alexander Bateman
- Department of Medical Imaging, John Hunter Hospital, Newcastle, NSW 2305, Australia
- Faculty of Health, Callaghan Campus, University of Newcastle, Newcastle, NSW 2308, Australia
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Yamakuni R, Seino S, Ishii S, Ishikawa H, Kikori K, Ando T, Kakamu T, Fukushima K, Otani K, Ito H. Lumbar intradural space reduction during the Valsalva maneuver observed using cine MRI and MR myelography: a single-case experimental study. Acta Neurochir (Wien) 2023; 165:2111-2120. [PMID: 37341825 DOI: 10.1007/s00701-023-05678-4] [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: 04/23/2023] [Accepted: 06/13/2023] [Indexed: 06/22/2023]
Abstract
BACKGROUND Previous studies have shown that the Valsalva maneuver (VM) causes spinal canal object movements. We hypothesized that this occurs because of cerebrospinal fluid (CSF) flow generated from intradural space reduction. Previous studies using myelograms reported lumbar CSF space changes during inspiration. However, no similar studies have been conducted using modern MRI. Therefore, this study analyzed intradural space reduction during the VM using cine magnetic resonance imaging (MRI). METHODS The participant was a 39-year-old, healthy, male volunteer. Cine MRI involved fast imaging employing steady-state acquisition cine sequence during three resting and VM sets for 60 s each. The axial plane was at the intervertebral disc and vertebral body levels between Th12 and S1 during cine MRI. This examination was performed on 3 separate days; hence, data from nine resting and VM sets were available. Additionally, two-dimensional myelography was performed during rest and the VM. RESULTS Intradural space reduction was observed during the VM using cine MRI and myelography. The intradural space cross-sectional area during the VM (mean: 129.3 mm2; standard deviation [SD]: 27.4 mm2) was significantly lower than that during the resting period (mean: 169.8; SD: 24.8; Wilcoxon signed-rank test, P < 0.001). The reduction rate of the vertebral body level (mean: 26.7%; SD: 9.4%) was larger than that of the disc level (mean: 21.4%; SD: 9.5%; Wilcoxon rank sum test, P = 0.0014). Furthermore, the reduction was mainly observed on the ventral and bilateral intervertebral foramina sides at the vertebral body and intervertebral disc levels, respectively. CONCLUSION The intradural space was reduced during the VM, possibly because of venous dilatation. This phenomenon may be associated with CSF flow, intradural object movement, and nerve compression, potentially leading to back pain.
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Affiliation(s)
- Ryo Yamakuni
- Department of Radiology and Nuclear Medicine, Fukushima Medical University School of Medicine, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan.
| | - Shinya Seino
- Department of Radiology, Fukushima Medical University Hospital, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Shiro Ishii
- Department of Radiology and Nuclear Medicine, Fukushima Medical University School of Medicine, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Hironobu Ishikawa
- Department of Radiology, Fukushima Medical University Hospital, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Katsuyuki Kikori
- Department of Radiology, Fukushima Medical University Hospital, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Tatsuya Ando
- Department of Radiology and Nuclear Medicine, Fukushima Medical University School of Medicine, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Takeyasu Kakamu
- Department of Hygiene and Preventive Medicine, Fukushima Medical University School of Medicine, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Kenji Fukushima
- Department of Radiology and Nuclear Medicine, Fukushima Medical University School of Medicine, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Koji Otani
- Department of Orthopedic Surgery, Fukushima Medical University School of Medicine, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
| | - Hiroshi Ito
- Department of Radiology and Nuclear Medicine, Fukushima Medical University School of Medicine, 1 Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan
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Bessen MA, Gayen CD, Quarrington RD, Walls AC, Leonard AV, Kurtcuoglu V, Jones CF. Characterising spinal cerebrospinal fluid flow in the pig with phase-contrast magnetic resonance imaging. Fluids Barriers CNS 2023; 20:5. [PMID: 36653870 PMCID: PMC9850564 DOI: 10.1186/s12987-022-00401-4] [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] [Received: 08/16/2022] [Accepted: 12/13/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Detecting changes in pulsatile cerebrospinal fluid (CSF) flow may assist clinical management decisions, but spinal CSF flow is relatively understudied. Traumatic spinal cord injuries (SCI) often cause spinal cord swelling and subarachnoid space (SAS) obstruction, potentially causing pulsatile CSF flow changes. Pigs are emerging as a favoured large animal SCI model; therefore, the aim of this study was to characterise CSF flow along the healthy pig spine. METHODS Phase-contrast magnetic resonance images (PC-MRI), retrospectively cardiac gated, were acquired for fourteen laterally recumbent, anaesthetised and ventilated, female domestic pigs (22-29 kg). Axial images were obtained at C2/C3, T8/T9, T11/T12 and L1/L2. Dorsal and ventral SAS regions of interest (ROI) were manually segmented. CSF flow and velocity were determined throughout a cardiac cycle. Linear mixed-effects models, with post-hoc comparisons, were used to identify differences in peak systolic/diastolic flow, and maximum velocity (cranial/caudal), across spinal levels and dorsal/ventral SAS. Velocity wave speed from C2/C3 to L1/L2 was calculated. RESULTS PC-MRI data were obtained for 11/14 animals. Pulsatile CSF flow was observed at all spinal levels. Peak systolic flow was greater at C2/C3 (dorsal: - 0.32 ± 0.14 mL/s, ventral: - 0.15 ± 0.13 mL/s) than T8/T9 dorsally (- 0.04 ± 0.03 mL/s; p < 0.001), but not different ventrally (- 0.08 ± 0.08 mL/s; p = 0.275), and no difference between thoracolumbar levels (p > 0.05). Peak diastolic flow was greater at C2/C3 (0.29 ± 0.08 mL/s) compared to T8/T9 (0.03 ± 0.03 mL/s, p < 0.001) dorsally, but not different ventrally (p = 1.000). Cranial and caudal maximum velocity at C2/C3 were greater than thoracolumbar levels dorsally (p < 0.001), and T8/T9 and L1/L2 ventrally (p = 0.022). Diastolic velocity wave speed was 1.41 ± 0.39 m/s dorsally and 1.22 ± 0.21 m/s ventrally, and systolic velocity wave speed was 1.02 ± 0.25 m/s dorsally and 0.91 ± 0.22 m/s ventrally. CONCLUSIONS In anaesthetised and ventilated domestic pigs, spinal CSF has lower pulsatile flow and slower velocity wave propagation, compared to humans. This study provides baseline CSF flow at spinal levels relevant for future SCI research in this animal model.
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Affiliation(s)
- Madeleine Amy Bessen
- grid.1010.00000 0004 1936 7304Adelaide Spinal Research Group and Centre for Orthopaedics and Trauma Research, Adelaide Medical School, The University of Adelaide, Level 7, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA 5005 Australia
| | - Christine Diana Gayen
- grid.1010.00000 0004 1936 7304Adelaide Spinal Research Group and Centre for Orthopaedics and Trauma Research, Adelaide Medical School, The University of Adelaide, Level 7, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA 5005 Australia ,grid.1010.00000 0004 1936 7304Translational Neuropathology Laboratory, School of Biomedicine, The University of Adelaide, Level 2, Helen Mayo North Building, The University of Adelaide, Frome Road, Adelaide, SA 5005 Australia
| | - Ryan David Quarrington
- grid.1010.00000 0004 1936 7304Adelaide Spinal Research Group and Centre for Orthopaedics and Trauma Research, Adelaide Medical School, The University of Adelaide, Level 7, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA 5005 Australia ,grid.1010.00000 0004 1936 7304School of Electrical and Mechanical Engineering, The University of Adelaide, North Terrace, Adelaide, SA 5005 Australia
| | - Angela Catherine Walls
- grid.430453.50000 0004 0565 2606Clinical and Research Imaging Centre, South Australian Health and Medical Research Institute, National Imaging Facility, Northern Pod, SAHMRI, North Terrace, Adelaide, SA 5000 Australia
| | - Anna Victoria Leonard
- grid.1010.00000 0004 1936 7304Translational Neuropathology Laboratory, School of Biomedicine, The University of Adelaide, Level 2, Helen Mayo North Building, The University of Adelaide, Frome Road, Adelaide, SA 5005 Australia
| | - Vartan Kurtcuoglu
- grid.7400.30000 0004 1937 0650Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland ,grid.7400.30000 0004 1937 0650Zurich Center for Integrative Human Physiology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland ,grid.7400.30000 0004 1937 0650Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Claire Frances Jones
- grid.1010.00000 0004 1936 7304Adelaide Spinal Research Group and Centre for Orthopaedics and Trauma Research, Adelaide Medical School, The University of Adelaide, Level 7, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA 5005 Australia ,grid.1010.00000 0004 1936 7304School of Electrical and Mechanical Engineering, The University of Adelaide, North Terrace, Adelaide, SA 5005 Australia ,grid.416075.10000 0004 0367 1221Department of Orthopaedics, Royal Adelaide Hospital, Adelaide, SA 5000 Australia
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