scholarly journals On the bulk motion of the cerebrospinal fluid in the spinal canal

2018 ◽  
Vol 841 ◽  
pp. 203-227 ◽  
Author(s):  
A. L. Sánchez ◽  
C. Martínez-Bazán ◽  
C. Gutiérrez-Montes ◽  
E. Criado-Hidalgo ◽  
G. Pawlak ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Subarachnoid Space ◽  
Spinal Canal ◽  
Lumbar Region ◽  
Leading Order ◽  
Steady Streaming ◽  
Viscous Forces ◽  
Recirculating Flow ◽  
Radiological Measurements

Radionuclide scanning images published inNatureby Di Chiro in 1964 showed a downward migration along the spinal canal of particle tracers injected in the brain ventricles while also showing an upward flow of tracers injected in the lumbar region of the canal. These observations, since then corroborated by many radiological measurements, have been the basis for the hypothesis that there must be an active circulation mechanism associated with the transport of cerebrospinal fluid (CSF) deep down into the spinal canal and subsequently returning a portion back to the cranial vault. However, to date, there has been no physical explanation for the mechanism responsible for the establishment of such a bulk recirculating motion. To investigate the origin and characteristics of this recirculating flow, we have analyzed the motion of the CSF in the subarachnoid space of the spinal canal. Our analysis accounts for the slender geometry of the spinal canal, the small compliance of the dura membrane enclosing the CSF in the canal, and the fact that the CSF is confined to a thin annular subarachnoid space surrounding the spinal cord. We apply this general formulation to study the characteristics of the flow generated in a simplified model of the spinal canal consisting of a slender compliant cylindrical pipe with a coaxial cylindrical inclusion, closed at its distal end, and subjected to small periodic pressure pulsations at its open entrance. We show that the balance between the local acceleration and viscous forces produces a leading-order flow consisting of pure oscillatory motion with axial velocities on the order of a few centimetres per second and amplitudes monotonically decreasing along the length of the canal. We then demonstrate that the nonlinear term associated with the convective acceleration contributes to a second-order correction consisting of a steady streaming that generates a bulk recirculating motion of the CSF along the length of the canal with characteristic velocities two orders of magnitude smaller than the leading-order oscillatory flow. The results of the analysis of this idealized geometry of the spinal canal are shown to be in good agreement not only with experimental measurements in anin-vitromodel but also with radiological measurements conducted in human adults.

scholarly journals In vitro and Numerical Simulation of Blood Removal from Cerebrospinal Fluid: Comparison of Lumbar Drain to Neurapheresis Therapy

2020 ◽  
Author(s):  
Mohammadreza Khani ◽  
Lucas Sass ◽  
M. Keith Sharp ◽  
Aaron McCabe ◽  
Laura Zitella Verbick ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Subarachnoid Space ◽  
Cfd Model ◽  
Tracer Concentration ◽  
Steady Streaming ◽  
Lumbar Drain ◽  
Spinal Subarachnoid Space ◽  
Subject Specific ◽  
The Impact

Abstract Background: Blood removal from cerebrospinal fluid (CSF) in post-subarachnoid hemorrhage patients may reduce the risk of related secondary brain injury. We formulated a computational fluid dynamics (CFD) model to investigate the impact of a dual-lumen catheter-based CSF filtration system, called Neurapheresis TM therapy, on blood removal from CSF compared to lumbar drain. Methods: A subject-specific multiphase CFD model of CSF system-wide solute transport was constructed based on MRI measurements. The Neurapheresis catheter geometry was added to the model within the spinal subarachnoid space. Neurapheresis flow aspiration and return rate was 2.0 and 1.8 (mL/min), versus 0.2 (mL/min) drainage for lumbar drain. Blood was modeled as a bulk fluid phase within CSF with a 10% initial tracer concentration and identical viscosity and density as CSF. Subject-specific oscillatory CSF flow was applied at the model inlet. The dura and spinal cord geometry were considered to be stationary. Spatial-temporal tracer concentration was quantified based on time-average steady-streaming velocities throughout the domain under Neurapheresis therapy and lumbar drain. To help verify CFD results, an optically clear in vitro CSF model was constructed with fluorescein used as a blood surrogate. Quantitative comparison of numerical and in vitro results was performed by linear regression of spatial-temporal tracer concentration over 24-hours. Results: After 24-hours, tracer concentration was reduced to 4.9% under Neurapheresis therapy compared to 6.5% under lumbar drain. Tracer clearance was most rapid between the catheter aspiration and return ports. Neurapheresis therapy was found to have a greater impact on steady-streaming compared to lumbar drain. Steady-streaming in the cranial SAS was ~50X smaller than in the spinal subarachnoid space for both cases. CFD results were strongly correlated with the in vitro spatial-temporal tracer concentration under Neurapheresis therapy (R 2 =0.89 with +2.13% and -1.93% tracer concentration confidence interval). Conclusion: A subject-specific CFD model of CSF system-wide solute transport was used to investigate the impact of Neurapheresis therapy on tracer removal from CSF compared to lumbar drain over a 24-hour period. Neurapheresis therapy was found to substantially increase tracer clearance compared to lumbar drain. The multiphase CFD results were verified by in vitro fluorescein tracer experiments.

scholarly journals In vitro and Numerical Simulation of Blood Removal from Cerebrospinal Fluid: Comparison of Lumbar Drain to Neurapheresis Therapy

2020 ◽  
Author(s):  
Mohammadreza Khani ◽  
Lucas Sass ◽  
M. Keith Sharp ◽  
Aaron McCabe ◽  
Laura Zitella Verbick ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Subarachnoid Space ◽  
Cfd Model ◽  
Tracer Concentration ◽  
Steady Streaming ◽  
Lumbar Drain ◽  
Spinal Subarachnoid Space ◽  
Subject Specific ◽  
The Impact

Abstract Background: Blood removal from cerebrospinal fluid (CSF) in post-subarachnoid hemorrhage patients may reduce the risk of related secondary brain injury. We formulated a computational fluid dynamics (CFD) model to investigate the impact of a dual-lumen catheter-based CSF filtration system, called Neurapheresis TM therapy, on blood removal from CSF compared to lumbar drain. Methods: A subject-specific multiphase CFD model of CSF system-wide solute transport was constructed based on MRI measurements. The Neurapheresis catheter geometry was added to the model within the spinal subarachnoid space. Neurapheresis flow aspiration and return rate was 2.0 and 1.8 (mL/min), versus 0.2 (mL/min) drainage for lumbar drain. Blood was modeled as a bulk fluid phase within CSF with a 10% initial tracer concentration and identical viscosity and density as CSF. Subject-specific oscillatory CSF flow was applied at the model inlet. The dura and spinal cord geometry were considered to be stationary. Spatial-temporal tracer concentration was quantified based on time-average steady-streaming velocities throughout the domain under Neurapheresis therapy and lumbar drain. To help verify CFD results, an optically clear in vitro CSF model was constructed with fluorescein used as a blood surrogate. Quantitative comparison of numerical and in vitro results was performed by linear regression of spatial-temporal tracer concentration over 24-hours. Results: After 24-hours, tracer concentration was reduced to 4.9% under Neurapheresis therapy compared to 6.5% under lumbar drain. Tracer clearance was most rapid between the catheter aspiration and return ports. Neurapheresis therapy was found to have a greater impact on steady-streaming compared to lumbar drain. Steady-streaming in the cranial SAS was ~50X smaller than in the spinal subarachnoid space for both cases. CFD results were strongly correlated with the in vitro spatial-temporal tracer concentration under Neurapheresis therapy (R 2 =0.89 with +2.13% and -1.93% tracer concentration confidence interval). Conclusion: A subject-specific CFD model of CSF system-wide solute transport was used to investigate the impact of Neurapheresis therapy on tracer removal from CSF compared to lumbar drain over a 24-hour period. Neurapheresis therapy was found to substantially increase tracer clearance compared to lumbar drain. The multiphase CFD results were verified by in vitro fluorescein tracer experiments.

scholarly journals A Poroelastic Fluid/Structure-Interaction Model of Cerebrospinal Fluid Dynamics in the Cord With Syringomyelia and Adjacent Subarachnoid-Space Stenosis

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
C. D. Bertram ◽  
M. Heil
Keyword(s):  
Cerebrospinal Fluid ◽  
Subarachnoid Space ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Porous Solids ◽  
Pia Mater ◽  
Fluid Structure ◽  
Steady Streaming ◽  
Structure Interaction ◽  
Mean Pressure

An existing axisymmetric fluid/structure-interaction (FSI) model of the spinal cord, pia mater, subarachnoid space, and dura mater in the presence of syringomyelia and subarachnoid-space stenosis was modified to include porous solids. This allowed investigation of a hypothesis for syrinx fluid ingress from cerebrospinal fluid (CSF). Gross model deformation was unchanged by the addition of porosity, but pressure oscillated more in the syrinx and the subarachnoid space below the stenosis. The poroelastic model still exhibited elevated mean pressure in the subarachnoid space below the stenosis and in the syrinx. With realistic cord permeability, there was slight oscillatory shunt flow bypassing the stenosis via the porous tissue over the syrinx. Weak steady streaming flow occurred in a circuit involving craniocaudal flow through the stenosis and back via the syrinx. Mean syrinx volume was scarcely altered when the adjacent stenosis bisected the syrinx, but increased slightly when the syrinx was predominantly located caudal to the stenosis. The fluid content of the tissues over the syrinx oscillated, absorbing most of the radial flow seeping from the subarachnoid space so that it did not reach the syrinx. To a lesser extent, this cyclic swelling in a boundary layer of cord tissue just below the pia occurred all along the cord, representing a mechanism for exchange of interstitial fluid (ISF) and cerebrospinal fluid which could explain recent tracer findings without invoking perivascular conduits. The model demonstrates that syrinx volume increase is possible when there is subarachnoid-space stenosis and the cord and pia are permeable.

The Influence of Coughing on Cerebrospinal Fluid Pressure in an In Vitro Syringomyelia Model With Spinal Canal Stenosis

2009 ◽  
Author(s):  
Bryn A. Martin ◽  
Francis Loth
Keyword(s):  
Cerebrospinal Fluid ◽  
Spinal Canal ◽  
Fluid Pressure ◽  
In Vitro Models ◽  
Spinal Canal Stenosis ◽  
Pressure Gradients ◽  
Canal Stenosis ◽  
Large Pressure ◽  
Type Flow

Five in vitro models were constructed which were representative of various pathologies of the spinal canal (SC) associated with syringomyelia (SM). The models were subjected to a cough type flow impulse while monitoring the pressure environment in the syrinx and subarachnoid space (SAS) regions of the model. The results indicated that conditions can arise during a cough which would provide pressure forces to encourage cerebrospinal fluid (CSF) movement into the syrinx cavity. The flow obstruction (stenosis) acted as an inflection point for transmural pressure (TP) in which the far region of the syrinx was expanded and the near region was compressed. In the case when a stenosis was present, but no syrinx had formed, the longitudinal pressure gradient and pulse pressures were highest on the SC. However, when a syrinx was present, the pressures were reduced, but still pathological. The primary point of pressure gradients in all of the experiments was the stenosis which caused large pressure dissociation in the system which could aid in SC ripping or tearing of the tissue. The presence of a syrinx appeared to decrease some of these forces, but without removal of the flow obstruction, a pathological biomechanical environment persists.

Computational Analysis of Cerebrospinal Fluid Flow in the Normal and Obstructed Subarachnoid Space

2008 ◽  
Author(s):  
Alejandro Roldán ◽  
Victor Haughton ◽  
Tim Osswald ◽  
Naomi Chesler
Keyword(s):  
Cerebrospinal Fluid ◽  
Subarachnoid Space ◽  
Spinal Canal ◽  
Numerical Technique ◽  
Patient Specific ◽  
Shear Stresses ◽  
Csf Flow ◽  
Flow Rates ◽  
Cerebrospinal Fluid Flow ◽  
The Impact

Patients with Chiari I malformations have increased cerebrospinal fluid (CSF) velocities compared to subjects without the malformation. Improved methods of analyzing the CSF fluid dynamics are needed to evaluate the impact of increased fluid velocities on pressure differentials in the upper cervical spinal canal and the potential impact of surgery on flow dynamics in patient-specific geometries. Here, a numerical technique based on the boundary elements method (BEM) for modeling the CSF flow within the spinal canal is presented. Results for velocity and pressure throughout the spinal canal were obtained at flow rates representative of different phases of the cardiac cycle for a healthy geometry and a Chiari model. In the healthy geometry, peak CSF velocities occurred anterolateral to the spinal cord at all flow rates. Partially obstructing the subarachnoid space increased peak systolic and diastolic velocities and shear stresses anteriorly. In addition, in the obstructed (Chiari) model, stagnation regions were evident posteriorly. The effects of surgical treatment on these CSF flow patterns warrant further study.

scholarly journals In vitro and Numerical Simulation of Blood Removal from Cerebrospinal Fluid: Comparison of Lumbar Drain to Neurapheresis Therapy

2020 ◽  
Author(s):  
Mohammadreza Khani ◽  
Lucas Sass ◽  
M. Keith Sharp ◽  
Aaron McCabe ◽  
Laura Zitella Verbick ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Solute Transport ◽  
Cfd Model ◽  
Tracer Concentration ◽  
Steady Streaming ◽  
Lumbar Drain ◽  
Subject Specific ◽  
Multiphase Cfd ◽  
The Impact

Abstract Background: Blood removal from cerebrospinal fluid (CSF) in post-subarachnoid hemorrhage patients may reduce the risk of related secondary brain injury. We formulated a computational fluid dynamics (CFD) model to investigate the impact of a dual-lumen catheter-based CSF filtration system, called NeurapheresisTM therapy, on blood removal from CSF compared to lumbar drain. Methods: A subject-specific multiphase CFD model of CSF system-wide solute transport was constructed based on MRI measurements. The Neurapheresis catheter geometry was added to the model within the spinal subarachnoid space (SAS). Neurapheresis flow aspiration and return rate was 2.0 and 1.8 mL/min, versus 0.2 mL/min drainage for lumbar drain. Blood was modeled as a bulk fluid phase within CSF with a 10% initial tracer concentration and identical viscosity and density as CSF. Subject-specific oscillatory CSF flow was applied at the model inlet. The dura and spinal cord geometry were considered to be stationary. Spatial-temporal tracer concentration was quantified based on time-average steady-streaming velocities throughout the domain under Neurapheresis therapy and lumbar drain. To help verify CFD results, an optically clear in vitro CSF model was constructed with fluorescein used as a blood surrogate. Quantitative comparison of numerical and in vitro results was performed by linear regression of spatial-temporal tracer concentration over 24-hours.Results: After 24-hours, tracer concentration was reduced to 4.9% under Neurapheresis therapy compared to 6.5% under lumbar drain. Tracer clearance was most rapid between the catheter aspiration and return ports. Neurapheresis therapy was found to have a greater impact on steady-streaming compared to lumbar drain. Steady-streaming in the cranial SAS was ~50X smaller than in the spinal SAS for both cases. CFD results were strongly correlated with the in vitro spatial-temporal tracer concentration under Neurapheresis therapy (R2=0.89 with +2.13% and -1.93% tracer concentration confidence interval). Conclusion: A subject-specific CFD model of CSF system-wide solute transport was used to investigate the impact of Neurapheresis therapy on tracer removal from CSF compared to lumbar drain over a 24-hour period. Neurapheresis therapy was found to substantially increase tracer clearance compared to lumbar drain. The multiphase CFD results were verified by in vitro fluorescein tracer experiments.

Spinal Subarachnoid Space Pressure Measurements in an In Vitro Spinal Stenosis Model: Implications on Syringomyelia Theories

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Bryn A. Martin ◽  
Richard Labuda ◽  
Thomas J. Royston ◽  
John N. Oshinski ◽  
Bermans Iskandar ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Spinal Stenosis ◽  
Subarachnoid Space ◽  
Computational Models ◽  
Spinal Column ◽  
Valve Mechanism ◽  
Tissue Properties ◽  
Csf Pressure

Full explanation for the pathogenesis of syringomyelia (SM), a neuropathology characterized by the formation of a cystic cavity (syrinx) in the spinal cord (SC), has not yet been provided. It has been hypothesized that abnormal cerebrospinal fluid (CSF) pressure, caused by subarachnoid space (SAS) flow blockage (stenosis), is an underlying cause of syrinx formation and subsequent pain in the patient. However, paucity in detailed in vivo pressure data has made theoretical explanations for the syrinx difficult to reconcile. In order to understand the complex pressure environment, four simplified in vitro models were constructed to have anatomical similarities with post-traumatic SM and Chiari malformation related SM. Experimental geometry and properties were based on in vivo data and incorporated pertinent elements such as a realistic CSF flow waveform, spinal stenosis, syrinx, flexible SC, and flexible spinal column. The presence of a spinal stenosis in the SAS caused peak-to-peak cerebrospinal fluid CSF pressure fluctuations to increase rostral to the stenosis. Pressure with both stenosis and syrinx present was complex. Overall, the interaction of the syrinx and stenosis resulted in a diastolic valve mechanism and rostral tensioning of the SC. In all experiments, the blockage was shown to increase and dissociate SAS pressure, while the axial pressure distribution in the syrinx remained uniform. These results highlight the importance of the properties of the SC and spinal SAS, such as compliance and permeability, and provide data for comparison with computational models. Further research examining the influence of stenosis size and location, and the importance of tissue properties, is warranted.

scholarly journals Cerebrospinal fluid (CSF) augments metabolism and virulence expression factors in Acinetobacter baumannii

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jasmine Martinez ◽  
Chelsea Razo-Gutierrez ◽  
Casin Le ◽  
Robert Courville ◽  
Camila Pimentel ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Acinetobacter Baumannii ◽  
Virulence Factors ◽  
Atp Synthesis ◽  
Bloodstream Infections ◽  
Model Systems ◽  
Phenotypic Traits ◽  
Virulence Determinants ◽  
Expression Of Genes

AbstractIn a recent report by the Centers for Disease Control and Prevention (CDC), multidrug resistant (MDR) Acinetobacter baumannii is a pathogen described as an “urgent threat.” Infection with this bacterium manifests as different diseases such as community and nosocomial pneumonia, bloodstream infections, endocarditis, infections of the urinary tract, wound infections, burn infections, skin and soft tissue infections, and meningitis. In particular, nosocomial meningitis, an unwelcome complication of neurosurgery caused by extensively-drug resistant (XDR) A. baumannii, is extremely challenging to manage. Therefore, understanding how A. baumannii adapts to different host environments, such as cerebrospinal fluid (CSF) that may trigger changes in expression of virulence factors that are associated with the successful establishment and progress of this infection is necessary. The present in-vitro work describes, the genetic changes that occur during A. baumannii infiltration into CSF and displays A. baumannii’s expansive versatility to persist in a nutrient limited environment while enhancing several virulence factors to survive and persist. While a hypervirulent A. baumannii strain did not show changes in its transcriptome when incubated in the presence of CSF, a low-virulence isolate showed significant differences in gene expression and phenotypic traits. Exposure to 4% CSF caused increased expression of virulence factors such as fimbriae, pilins, and iron chelators, and other virulence determinants that was confirmed in various model systems. Furthermore, although CSF's presence did not enhance bacterial growth, an increase of expression of genes encoding transcription, translation, and the ATP synthesis machinery was observed. This work also explores A. baumannii’s response to an essential component, human serum albumin (HSA), within CSF to trigger the differential expression of genes associated with its pathoadaptibility in this environment.

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