scholarly journals The myodural bridge of the American alligator (Alligator mississippiensis) alters CSF flow

2020 ◽  
Vol 223 (22) ◽  
pp. jeb230896
Author(s):  
Bruce A. Young ◽  
James Adams ◽  
Jonathan M. Beary ◽  
Kent-Andre Mardal ◽  
Robert Schneider ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Cerebrospinal Fluid ◽  
Alligator Mississippiensis ◽  
American Alligator ◽  
Csf Flow ◽  
Csf Pressure ◽  
Csf Circulation ◽  
Disease States ◽  
American Alligators ◽  
Myodural Bridge

ABSTRACTDisorders of the volume, pressure or circulation of the cerebrospinal fluid (CSF) lead to disease states in both newborns and adults; despite this significance, there is uncertainty regarding the basic mechanics of the CSF. The suboccipital muscles connect to the dura surrounding the spinal cord, forming a complex termed the ‘myodural bridge’. This study tests the hypothesis that the myodural bridge functions to alter the CSF circulation. The suboccipital muscles of American alligators were surgically exposed and electrically stimulated simultaneously with direct recordings of CSF pressure and flow. Contraction of the suboccipital muscles significantly changed both CSF flow and pressure. By demonstrating another influence on CSF circulation and pulsatility, the present study increases our understanding of the mechanics underlying the movement of the CSF.

A Fluid Structure Interaction Simulation of the Cerebrospinal Fluid, Spinal Cord, and Spinal Stenosis Present in Syringomyelia

2010 ◽  
Author(s):  
Yifei Liu ◽  
Bryn A. Martin ◽  
Thomas J. Royston ◽  
Francis Loth
Keyword(s):  
Spinal Cord ◽  
Cerebrospinal Fluid ◽  
Wave Propagation ◽  
In Silico ◽  
Fluid Structure Interaction ◽  
Csf Flow ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Csf Pressure

Syringomyelia (SM) is a neurological disease in which a fluid-filled cystic cavity, or syrinx, forms in the spinal cord (SC) resulting in progressive loss of sensory, motor functions, and/or pain in the patient. It has been hypothesized that abnormal cerebrospinal fluid (CSF) pressure distribution and absorption in the subarachnoid space (SAS), resulting from a CSF flow blockage (stenosis), could be a key etiological factor for syrinx pathogenesis. In particular, the magnitude of the abrupt SAS pressure waves produced during coughing has been correlated with headache and pain in the patient. To better understand the influence of coughing on the spinal SAS, four axisymmetric fluid-structure interaction (FSI) in silico models representative of various conditions associated with SM were constructed. Each of the models was subjected to a cough-like CSF pressure pulse. The CSF flow stenosis was shown to attenuate and decelerate the CSF wave propagation in the SAS. The spinal SAS distensibility was also shown to have significant influence on the wave propagation. The in silico pressure results were found to be in agreement with a set of similar in vitro experiments [1].

scholarly journals Variations in the cerebrospinal fluid dynamics of the American alligator (Alligator mississippiensis)

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Bruce A. Young ◽  
James Adams ◽  
Jonathan M. Beary ◽  
Kent-Andre Mardal ◽  
Robert Schneider ◽  
...  
Keyword(s):  
Subarachnoid Space ◽  
Alligator Mississippiensis ◽  
American Alligator ◽  
Csf Flow ◽  
Csf Dynamics ◽  
Pressure Transducers ◽  
Csf Pressure ◽  
Evolutionary Origins ◽  
Unidirectional Flow ◽  
Ventilatory Mechanics

Abstract Background Studies of mammalian CSF dynamics have been focused on three things: paravascular flow, pressure and pulsatility, and “bulk” flow; and three (respective) potential motive forces have been identified: vasomotor, cardiac, and ventilatory. There are unresolved questions in each area, and few links between the different areas. The American alligator (Alligator mississippiensis) has pronounced plasticity in its ventilatory and cardiovascular systems. This study was designed to test the hypothesis that the greater cardiovascular and ventilatory plasticity of A. mississippiensis would result in more variation within the CSF dynamics of this species. Methods Pressure transducers were surgically implanted into the cranial subarachnoid space of 12 sub-adult alligators; CSF pressure and pulsatility were monitored along with EKG and the exhalatory gases. In four of the alligators a second pressure transducer was implanted into the spinal subarachnoid space. In five of the alligators the CSF was labeled with artificial microspheres and Doppler ultrasonography used to quantify aspects of the spinal CSF flow. Results Both temporal and frequency analyses of the CSF pulsations showed highly variable contributions of both the cardiac and ventilatory cycles. Unlike the mammalian condition, the CSF pressure pulsations in the alligator are often of long (~ 3 s) duration, and similar duration CSF unidirectional flow pulses were recorded along the spinal cord. Reduction of the duration of the CSF pulsations, as during tachycardia, can lead to a “summation” of the pulsations. There appears to be a minimum duration (~ 1 s) of isolated CSF pulsations. Simultaneous recordings of cranial and spinal CSF pressures reveal a 200 ms delay in the propagation of the pressure pulse from the cranium to the vertebral canal. Conclusions Most of the CSF flow dynamics recorded from the alligators, are similar to what has been reported from studies of the human CSF. It is hypothesized that the link between ventilatory mechanics and CSF pulsations in the alligator is mediated by displacement of the spinal dura. The results of the study suggest that understanding the CSF dynamics of Alligator may provide unique insights into the evolutionary origins and functional regulation of the human CSF dynamics.

scholarly journals Head-nodding: a driving force for the circulation of cerebrospinal fluid

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qiang Xu ◽  
Chang-Xi Shao ◽  
Ying Zhang ◽  
Yu Zhang ◽  
Cong Liu ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Head Movement ◽  
Head Movements ◽  
Csf Flow ◽  
Csf Circulation ◽  
Head Nodding ◽  
Before And After ◽  
Contrast Magnetic Resonance ◽  
Myodural Bridge ◽  
The One

AbstractThe myodural bridge (MDB) is a dense connective tissue bridge connecting the suboccipital muscles to the spinal dura mater, and it has been proven to be a normal common existing structure in humans and mammals. Some scholars believe that the suboccipital muscles can serve as a dynamic cerebrospinal fluid (CSF) pump via the MDB, and they found head rotations promote the CSF flow in human body, which provided evidence for this hypothesis. Head movement is a complex motion, but the effects of other forms of head movement on CSF circulation are less known. The present study explored the effects of head-nodding on CSF circulation. The CSF flow of 60 healthy volunteers was analyzed via cine phase-contrast magnetic resonance imaging at the level of the occipitocervical junction before and after one-minute-head-nodding period. Furthermore, the CSF pressures of 100 volunteers were measured via lumbar puncture before and after 5 times head-nodding during their anesthetizing for surgical preparation. As a result, it was found that the maximum and average CSF flow rates at the level of the upper border of atlas during ventricular diastole were significantly decreased from 1.965 ± 0.531 to 1.839 ± 0.460 ml/s and from 0.702 ± 0.253 to 0.606 ± 0.228 ml/s respectively. In the meantime, the changes in the ratio of cranial and caudal orientation of the net flow volume were found differed significantly after the one-minute-head-nodding period (p = 0.017). And on the other hand, the CSF pressures at the L3–L4 level were markedly increased 116.03 ± 26.13 to 124.64 ± 26.18 mmH2O. In conclusion, the head-nodding has obvious effects on CSF circulation and head movement is one of the important drivers of cerebrospinal fluid circulation. We propose that the suboccipital muscles, participating in various head movements, might pull the dura sac via the myodural bridge, and thus, head movement provides power for the CSF circulation.

Evaluation of the central canal of the spinal cord in experimentally induced hydrocephalus

1978 ◽  
Vol 48 (6) ◽  
pp. 970-974 ◽  
Author(s):  
A. Everette James ◽  
William J. Flor ◽  
Gary R. Novak ◽  
Ernst-Peter Strecker ◽  
Barry Burns
Keyword(s):  
Spinal Cord ◽  
Cerebrospinal Fluid ◽  
Experimental Model ◽  
Alternative Pathway ◽  
Central Canal ◽  
Communicating Hydrocephalus ◽  
Csf Flow ◽  
Content Type ◽  
Histological Appearance ◽  
Fine Print

✓ The central canal of the spinal cord has been proposed as a significant compensatory alternative pathway of cerebrospinal fluid (CSF) flow in hydrocephalus. Ten dogs were made hydrocephalic by a relatively atraumatic experimental model that simulates the human circumstance of chronic communicating hydrocephalus. The central canal was studied by histopathology and compared with 10 normal control dogs. In both groups the central canal of the spinal cord was normal in size, configuration, and histological appearance. In this experimental model dilatation of the canal and increased movement of CSF does not appear to be a compensatory alternative pathway.

Changes in Cerebrospinal Fluid Pressure and Lactate Concentrations during Thoracoabdominal Aortic Aneurysm Surgery

1997 ◽  
Vol 86 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Benjamin Drenger ◽  
Stephen D. Parker ◽  
Steven M. Frank ◽  
Charles Beattie
Keyword(s):  
Spinal Cord ◽  
Cerebrospinal Fluid ◽  
Aortic Aneurysm ◽  
Aortic Surgery ◽  
Thoracoabdominal Aortic Aneurysm ◽  
Aortic Occlusion ◽  
Aneurysm Surgery ◽  
Csf Pressure ◽  
Csf Lactate ◽  
Aortic Aneurysm Surgery

Background Although ischemic injury to the spinal cord is a well-known complication of aortic surgery, no metabolic markers have been identified as predictors of an adverse outcome. This study evaluated the effect of cerebrospinal fluid (CSF) drainage, with and without distal femoral perfusion or moderate hypothermia on blood and CSF lactate concentrations and CSF pressure during thoracoabdominal aortic aneurysm surgery. Methods Three nonconcurrent groups of patients were studied prospectively: patients with normal body temperature (35 degrees C) but without distal femoral bypass (n = 6), patients with normal body temperature with bypass (n = 7), and patients with hypothermia (30 degrees C) and bypass (n = 8). In all patients, CSF pressure was recorded before, during, and after aortic cross-clamping. During the surgical repair, CSF drainage was performed using a 4-Fr intrathecal silicone catheter. Blood and CSF lactate concentrations were measured throughout the operation. Results Significant increases in blood (490%) and CSF (173%) lactate concentrations were observed during and after thoracic aortic occlusion in patients with normothermia and no bypass (P < 0.02 and 0.05, respectively). Distal perfusion attenuated the increase in both blood and CSF lactate (P < 0.01), and a further reduction was achieved with hypothermia of 30 degrees C (P < 0.001). Patients who became paraplegic showed a greater increase in CSF lactate concentrations after aortic clamp release compared with those who suffered no neurological damage (275% vs. 123% of baseline; P < 0.05). Increased CSF pressure of 42-60% (P < 0.005) was noted soon after thoracic aortic occlusion, both with and without distal femoral bypass. Conclusions Incremental reductions in CSF lactate concentrations were achieved using distal femoral bypass and hypothermia. The reduction in CSF lactate correlated with the methods used to protect the spinal cord during thoracoabdominal aortic aneurysm surgery and was associated with better outcome. Decompression by distal bypass of the hemodynamic overload caused by aortic occlusion was insufficient to eliminate the acute increase in CSF pressure. Cerebrospinal fluid lactate measurements during high aortic surgery may accurately represent the spinal cord metabolic balance.

Subarachnoid–subarachnoid bypass: a new surgical technique for posttraumatic syringomyelia

2013 ◽  
Vol 18 (4) ◽  
pp. 382-387 ◽  
Author(s):  
Tetsuo Hayashi ◽  
Takayoshi Ueta ◽  
Masahiro Kubo ◽  
Takeshi Maeda ◽  
Keiichiro Shiba
Keyword(s):  
Spinal Cord ◽  
Surgical Technique ◽  
Csf Flow ◽  
Presenting Symptoms ◽  
Csf Circulation ◽  
Postoperative Mri ◽  
Cord Injury ◽  
The Mean ◽  
Posttraumatic Syringomyelia ◽  
Arachnoid Mater

Object The origin of posttraumatic syringomyelia is not completely understood. With respect to posttraumatic syringomyelia, the optimum management strategy for patients with spinal cord injury has also not been established. The authors hypothesized that reconstruction of the subarachnoid channels would reestablish CSF flow, thereby addressing the underlying cause of the syrinx formation. The authors performed a new type of surgery, subarachnoid–subarachnoid bypass (S–S bypass), in which an attempt was made to reestablish normal CSF circulation around the spinal cord. The purpose of this study was to evaluate the effectiveness of S–S bypass for posttraumatic syringomyelia. Methods Twenty consecutive patients with symptomatic posttraumatic syringomyelia who had progressive neurological symptoms and underwent S–S bypass were included in the study. The surgical procedure was as follows: a laminectomy was performed at the level of trauma, and a midline dural opening was made under a microscope. The arachnoid was exposed up to the area of normal arachnoid mater with normal CSF circulation. After dissection of the normal arachnoid mater at the cephalic and caudal sites, 1 or 2 tubes made of medical-grade silicone were inserted into the cephalic and caudal ends of the normal subarachnoid space. Bypass tubes were laid in the subdural space, and a watertight dural closure was accomplished using running sutures. The mean follow-up period was 48.2 months (range 12–93 months). The preoperative status and postoperative clinical course were assessed according to 3 grading systems: the Frankel grading system for global neurological status, the American Spinal Injury Association motor score for motor weakness, and the Klekamp system for bladder function. The major presenting symptoms or signs were assessed in terms of symptom improvement, stabilization, or deterioration. Preoperative and postoperative MRI was used to analyze the size and craniocaudal extension of the cavity. Results Twelve patients showed clinical improvement, 4 were stable, and 4 showed deterioration. The mean length of the syrinx observed on preoperative MRI was 9.9 spinal levels, and the mean Vaquero index was 62.3%. The mean length of the syrinx observed on postoperative MRI was 5.3 spinal levels, and the mean Vaquero index was 28.4%. These values were significantly lower than the preoperative values (p = 0.01 and p < 0.01, respectively). Conclusions This study showed that interference with CSF flow was the major cause of syrinx development and that reconstruction of CSF flow is the most important treatment strategy based on the cause of the syrinx. Subarachnoid–subarachnoid bypass, which can be performed without myelotomy, was not only a safe and effective surgical technique, but may also be a more physiological way of treating posttraumatic syringomyelia.

Limiting ischemic spinal cord injury using a free radical scavenger 21-aminosteroid and/or cerebrospinal fluid drainage

1993 ◽  
Vol 79 (5) ◽  
pp. 742-751 ◽  
Author(s):  
Paul C. Francel ◽  
Bruce A. Long ◽  
Jacek M. Malik ◽  
Curtis Tribble ◽  
John A. Jane ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Cerebrospinal Fluid ◽  
Perfusion Pressure ◽  
Ischemia And Reperfusion ◽  
Content Type ◽  
Csf Pressure ◽  
Csf Drainage ◽  
Cord Injury ◽  
Fine Print

✓ Traumatic spinal cord injury occurs in two phases: biomechanical injury, followed by ischemia and reperfusion injury. Biomechanical injury to the spinal cord, preceded or followed by various pharmaceutical manipulations or interventions, has been studied, but the ischemia/reperfusion aspect of spinal cord injury isolated from the biomechanical injury has not been previously evaluated. In the current study, ischemia to the lumbar spinal cord was induced in albino rabbits via infrarenal aortic occlusion, and two interventions were analyzed: the use of U74006F (Tirilazad mesylate), a 21-aminosteroid, and cerebrospinal fluid (CSF) drainage. These treatment modalities were tested alone or in combination. In Phase 1 of this study, the rabbits received 1.0 mg/kg of Tirilazad or an equal volume of vehicle (controls) prior to the actual occlusion, three doses of Tirilazad (1 mg/kg each) during the occlusion, then several doses after the occlusion. Of the Tirilazad-treated animals, 30% became paraplegic while 70% of the control animals became paraplegic. Phase 2 involved the same doses of Tirilazad as in Phase 1 and, in addition, CSF pressure monitoring and drainage were performed. The paraplegia rate was 79% in the control animals, 36% in the group receiving Tirilazad alone, 25% in the group with CSF drainage alone, and 20% in the Tirilazad plus CSF drainage group. This rate also correlated with changes noted in CSF pressure; both Tirilazad administration alone and CSF drainage alone induced a decrease in CSF pressure and the two combined produced a further decrease. There was marked improvement in the perfusion pressure when using Tirilazad alone, CSF drainage alone, and Tirilazad therapy in combination with CSF drainage, with the last group producing the largest increase. This change in CSF pressure and perfusion pressure correlated with improved functional neurological outcome. Pathological examination revealed that Tirilazad therapy reduced the extensive and diffuse neuronal, glial, and endothelial damage to (in its most severe form) a more patchy focal region of damage in the gray matter. Cerebrospinal fluid drainage resulted in pyknosis of some motor neurons, and some eosinophilia. The combination of CSF drainage and Tirilazad administration resulted in the least abnormality, with either normal or near-normal spinal cords. It is concluded that Tirilazad administration decreased CSF pressure during spinal cord ischemia and reperfusion and, like CSF drainage, increased and improved the perfusion pressure to the spinal cord, decreased spinal cord damage, and improved functional outcome. These effects may be related to the role that Tirilazad has on free radical scavenging during ischemia and reperfusion, and it is possible that Tirilazad therapy alone or in combination with CSF drainage is an effective adjunct to other neural protective measures in spinal cord injury.

Disturbances of Cerebrospinal Fluid Circulation during the Acute Stage of Subarachnoid Hemorrhage

Neurosurgery ◽  
1983 ◽  
Vol 12 (4) ◽  
pp. 435-438 ◽  
Author(s):  
Thomas Dóczi ◽  
Zoltán Nemessányi ◽  
Zsuzsa Szegváry ◽  
Endre Huszka
Keyword(s):  
Cerebrospinal Fluid ◽  
Subarachnoid Hemorrhage ◽  
Clinical Condition ◽  
Acute Stage ◽  
Normal Flow ◽  
Fluid Circulation ◽  
Csf Flow ◽  
Cerebrospinal Fluid Circulation ◽  
Csf Circulation ◽  
Flow Disturbances

Abstract Radioisotope cisternography was performed and the erythrocyte and hemoglobin contents of the cerebrospinal fluid (CSF) were determined within the first 4 days after subarachnoid hemorrhage in 42 patients. The clinical condition of the patients was related to the severity of the CSF circulation disturbances. Thirty-five patients had some degree of disturbance of CSF flow, and only 2 of the 42 patients had normal flow. In 5 cases the cisternograms were inconclusive. The severity of CSF circulation disturbances correlated well with clinical condition. No relationship was found between the number of erythrocytes in the CSF and the development of CSF circulation disturbances. The CSF erythrocyte content did not correlate with the clinical condition. It is suggested that flow disturbances of the CSF during the acute stage of subarachnoid hemorrhage might play an important role in the pathomechanism of the disease.

scholarly journals Anthropomorphic Model of Intrathecal Cerebrospinal Fluid Dynamics Within the Spinal Subarachnoid Space: Spinal Cord Nerve Roots Increase Steady-Streaming

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Mohammadreza Khani ◽  
Lucas R. Sass ◽  
Tao Xing ◽  
M. Keith Sharp ◽  
Olivier Balédent ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Spinal Cord ◽  
Cerebrospinal Fluid ◽  
Cfd Model ◽  
Csf Flow ◽  
Nerve Roots ◽  
Csf Dynamics ◽  
Steady Streaming ◽  
Spinal Subarachnoid Space ◽  
The Impact

Cerebrospinal fluid (CSF) dynamics are thought to play a vital role in central nervous system (CNS) physiology. The objective of this study was to investigate the impact of spinal cord (SC) nerve roots (NR) on CSF dynamics. A subject-specific computational fluid dynamics (CFD) model of the complete spinal subarachnoid space (SSS) with and without anatomically realistic NR and nonuniform moving dura wall deformation was constructed. This CFD model allowed detailed investigation of the impact of NR on CSF velocities that is not possible in vivo using magnetic resonance imaging (MRI) or other noninvasive imaging methods. Results showed that NR altered CSF dynamics in terms of velocity field, steady-streaming, and vortical structures. Vortices occurred in the cervical spine around NR during CSF flow reversal. The magnitude of steady-streaming CSF flow increased with NR, in particular within the cervical spine. This increase was located axially upstream and downstream of NR due to the interface of adjacent vortices that formed around NR.

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