Characteristics of CSF Velocity-Time Profile in Posttraumatic Syringomyelia

Cerebro-spinal flow pattern in the cervical subarachnoid space of healthy volunteers: Influence of the spinal cord morphology

INTRODUCTION

Toward further cerebro-spinal flow quantification in clinical practice, this study aims at assessing the variations in the cerebro spinal fluid flow pattern associated with change in the morphology of the subarachnoid space of the cervical canal of healthy humans by developing a computational fluid dynamics model.

METHODS

3D T2-space MRI sequence images of the cervical spine were used to segment 11 cervical subarachnoid space. Model validation (time-step, mesh size, size and number of boundary layers, influences of parted inflow and inflow continuous velocity) was performed a 40-year-old patient-specific model. Simulations were performed using computational fluid dynamics approach simulating transient flow (Sparlart-Almaras turbulence model) with a mesh size of 0.6, 6 boundary layers of 0.05 mm, a time step of 20 ms simulated on 15 cycles. Distributions of components velocity and WSS were respectively analyzed within the subarachnoid space (intervertebral et intravertebral levels) and on dura and pia maters.

RESULTS

Mean values cerebro spinal fluid velocity in specific local slices of the canal range between 0.07 and 0.17 m.s-1 and 0.1 and 0.3 m.s-1 for maximum values. Maximum wall shear stress values vary between 0.1 and 0.5 Pa with higher value at the middle of the cervical spine on pia mater and at the lower part of the cervical spine on dura mater. Intra and inter-individual variations of the wall shear stress were highlighted significant correlation gwith compression ratio (r = 0.76), occupation ratio and cross section area of the spinal cord.

CONCLUSION

The inter-individual variability in term of subarachnoid canal morphology and spinal cord position influence the cerebro-spinal flow pattern, highlighting the significance of canal morphology investigation before surgery.

Role of Preoperative Albumin Quotient in Surgical Planning for Posttraumatic Syringomyelia: A Comparative Cohort Study

OBJECTIVE

Surgical procedures for patients with posttraumatic syringomyelia (PTS) remain controversial. Until now, there have been no effective quantitative evaluation methods to assist in selecting appropriate surgical plans before surgery.

METHODS

We consecutively enrolled PTS patients (arachnoid lysis group, n = 42; shunting group, n = 14) from 2003 to 2023. Additionally, 19 intrathecal anesthesia patients were included in the control group. All patients with PTS underwent physical and neurological examinations and spinal magnetic resonance imaging preoperatively, 3-12 months postoperatively and during the last follow-up. Preoperative lumbar puncture was performed and blood-spinal cord barrier disruption was detected by quotient of albumin (Qalb, cerebrospinal fluid/serum).

RESULTS

The ages (p = 0.324) and sex (p = 0.065) of the PTS and control groups did not differ significantly. There were also no significant differences in age (p = 0.216), routine blood data and prognosis (p = 0.399) between the arachnoid lysis and shunting groups. But the QAlb level of PTS patients was significantly higher than that of the control group (p < 0.001), and the shunting group had a significantly higher QAlb (p < 0.001) than the arachnoid lysis group. A high preoperative QAlb (odds ratio, 1.091; 95% confidence interval, 1.004-1.187; p = 0.041) was identified as the predictive factor for the shunting procedure, with the receiver operating characteristic curve showing 100% specificity and 80.95% sensitivity for patients with a QAlb > 12.67.

CONCLUSION

Preoperative QAlb is a significant predictive factor for the types of surgery. For PTS patients with a QAlb > 12.67, shunting represents the final recourse, necessitating the exploration and development of novel treatments for these patients.

Characterising spinal cerebrospinal fluid flow in the pig with phase-contrast magnetic resonance imaging

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.

Fluids and flows in brain cancer and neurological disorders

Interstitial fluid (IF) and cerebrospinal fluid (CSF) are an integral part of the brain, serving to cushion and protect the brain parenchymal cells against damage and aid in their function. The brain IF contains various ions, nutrients, waste products, peptides, hormones, and neurotransmitters. IF moves primarily by pressure-dependent bulk flow through brain parenchyma, draining into the ventricular CSF. The brain ventricles and subarachnoid spaces are filled with CSF which circulates through the perivascular spaces. It also flows into the IF space regulated, in part, by aquaporin channels, removing waste solutes through a process of IF-CSF mixing. During disease development, the composition, flow, and volume of these fluids changes and can lead to brain cell dysfunction. With the improvement of imaging technology and the help of genomic profiling, more information has been and can be obtained from brain fluids; however, the role of CSF and IF in brain cancer and neurobiological disease is still limited. Here we outline recent advances of our knowledge of brain fluid flow in cancer and neurodegenerative disease based on our understanding of its dynamics and composition. This article is categorized under: Cancer > Biomedical Engineering Neurological Diseases > Biomedical Engineering.

Does Direct Surgical Decompression After Traumatic Spinal Cord Injury Influence Post-Traumatic Syringomyelia Rates? An 18-Year Single-Center Experience

OBJECTIVE

Risk factors for post-traumatic syringomyelia (PTS) development after traumatic spinal cord injury (tSCI) are incompletely understood. This study aimed to investigate the influence of direct surgical decompression after tSCI, as well as demographic, clinical, and other management-related factors, on rates of PTS development.

METHODS

A single-center case-control study was conducted on patients who presented with tSCI to a tertiary referral center over an 18-year period and received adequate follow-up. Cases were defined by both clinical suspicion and radiologic evidence of PTS. Demographic, clinical, and management-related data were collected and a multivariable logistic regression analysis performed.

RESULTS

A total of 286 patients were analyzed, of whom 33 (11.5%) demonstrated PTS. Direct surgical decompression with or without stabilization was performed in 190 of 286 patients, stabilization alone in 47, and non-surgical management in 49. On multivariable analysis, no significant influence on PTS risk was demonstrated for method of acute management (P > 0.05). A ten-year increase in age at injury was shown to decrease PTS rates by 0.72 (P = 0.01). Neurologically complete injury was associated with an increased rate of PTS, though this association did not achieve significance (P = 0.08). When only surgically managed patients were considered (n = 237), no significant influence on PTS rates was demonstrated for anterior decompression (adjusted odds ratio = 1.13, 95% CI = 0.34-3.74, P = 0.84) and for stabilization alone (adjusted odds ratio = 1.19, 95% CI = 0.39-3.61, P = 0.76) relative to posterior decompression.

CONCLUSIONS

Direct surgical decompression after tSCI was not demonstrated to significantly influence rates of PTS development. Age at injury and severity of injury should be considered as risk factors for PTS on follow-up.

In vitro evaluation of cerebrospinal fluid velocity measurement in type I Chiari malformation: repeatability, reproducibility, and agreement using 2D phase contrast and 4D flow MRI

BACKGROUND

Phase contrast magnetic resonance imaging, PC MRI, is a valuable tool allowing for non-invasive quantification of CSF dynamics, but has lacked adoption in clinical practice for Chiari malformation diagnostics. To improve these diagnostic practices, a better understanding of PC MRI based measurement agreement, repeatability, and reproducibility of CSF dynamics is needed.

METHODS

An anatomically realistic in vitro subject specific model of a Chiari malformation patient was scanned three times at five different scanning centers using 2D PC MRI and 4D Flow techniques to quantify intra-scanner repeatability, inter-scanner reproducibility, and agreement between imaging modalities. Peak systolic CSF velocities were measured at nine axial planes using 2D PC MRI, which were then compared to 4D Flow peak systolic velocity measurements extracted at those exact axial positions along the model.

RESULTS

Comparison of measurement results showed good overall agreement of CSF velocity detection between 2D PC MRI and 4D Flow (p = 0.86), fair intra-scanner repeatability (confidence intervals ± 1.5 cm/s), and poor inter-scanner reproducibility. On average, 4D Flow measurements had a larger variability than 2D PC MRI measurements (standard deviations 1.83 and 1.04 cm/s, respectively).

CONCLUSION

Agreement, repeatability, and reproducibility of 2D PC MRI and 4D Flow detection of peak CSF velocities was quantified using a patient-specific in vitro model of Chiari malformation. In combination, the greatest factor leading to measurement inconsistency was determined to be a lack of reproducibility between different MRI centers. Overall, these findings may help lead to better understanding for application of 2D PC MRI and 4D Flow techniques as diagnostic tools for CSF dynamics quantification in Chiari malformation and related diseases.

Syringomyelia and hydromyelia: Current understanding and neurosurgical management

Syringomyelia is a rare disorder in which a fluid-filled cyst forms within the spinal cord, resulting in myelopathy. Meanwhile, the abnormal dilatation of the central canal is referred to as hydromyelia or slit-like syrinx. The most prevailing classification is based on anatomical features and pathogeny rather than pathophysiological mechanisms. It is usual to distinguish foraminal syringomyelia related mainly to abnormalities at the craniocervical junction, non-foraminal syringomyelia dealing with any cause of arachnoiditis (infection, inflammation, trauma…) and more rarely syringomyelia associated with intramedullary tumors. Although many pathophysiological theories have been argued over time, the prevailing one is that disturbances in cerebrospinal fluid (CSF) flow in the sub-arachnoid spaces disrupt flow velocity leading to the syrinx. Symptoms of paralysis, sensory loss and chronic pain commonly develop during the third/fourth decades of life. The natural history of syringomyelia is typically one of gradual, stepwise neurological deterioration extending over many years. Diagnosis is based on magnetic resonance imaging (MRI) including excellent morphological sequences (T1-, T2-, FLAIR-, T2*-, enhanced T1-) and dynamic MRI with careful study of CSF velocity (CISS, cine-MR sequences). Surgical management is at first dedicated to treat the cause of the syringomyelia, mainly to re-establish a physiological CSF pathway in the subarachnoid spaces. Mostly, the surgical goal is to enlarge the craniocervical junction with duraplasty. Other surgical strategies such as arachnoidolysis or shunt procedures are performed based on the pathogenic mechanisms or as second-line treatment. Medical treatments are also necessary as chronic pain is the main long-lasting symptom. As evolutive syringomyelia is a severe disease with a high impact on quality of life, it is recommended to treat without delay. There is no evidence for surgery for incidental asymptomatic syringomyelia or hydromyelia. Finally, syringomyelia associated with intramedullary tumors resolves spontaneously after tumor resection. Syringomyelia is a rare disease, which requires a dedicated multidisciplinary approach, emphasizing the need for a nationwide scientific organization so as to offer optimal care to the patient.

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

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.

Comparison of the Efficiency of Transplantation of Rat and Human Olfactory Ensheathing Cells in Posttraumatic Cysts of the Spinal Cord

Olfactory ensheathing cells showed significant effects on the regeneration of the spinal cord in experimental models and in clinical trials. However, the use of these cells in the therapy of posttraumatic cysts of the spinal cord has not been studied. Cultures of human and rat olfactory mucosa were obtained according to the protocols developed by us. Passage 3-4 cultures are most enriched with olfactory ensheathing cells and are preferable for transplantation. We performed transplantation of 750,000 olfactory ensheathing cells into the region of modeled cysts. The therapeutic effect of human cells was more pronounced. The positive dynamics of recovery of motor activity in the hind limbs of rats can reflect regenerative processes in the spinal cord after transplantation of olfactory ensheathing cells into the region of posttraumatic cysts.

Acquired Chiari malformation following spinal cord injury-a case series

Introduction

Chiari malformation is characterized by caudal descent of the cerebellar tonsils through the foramen magnum. Acquired Chiari malformations (ACM) have previously been described after a variety of pathologies including lumbar puncture, cerebrospinal fluid (CSF) drainage, lumboperitoneal shunts, and conditions causing craniocephalic disproportion.

Case presentation

We present four cases of ACM following spinal cord injury (SCI), which has not previously been described in the literature.

Discussion

ACM is rare and typically associated with abnormalities in CSF pressure or space-occupying lesions. This case series describes the potential association of SCI with ACM. We discuss the imaging findings and clinical management of these patients. Early recognition and intervention may be important to prevent progressive neurology in this vulnerable patient group.

Thoracic Meningocele and Cervical Syringomyelia Treated with Ventriculoperitoneal Shunt

BACKGROUND

Spinal meningocele is the herniation of dura mater and cerebrospinal fluid through a spinal defect, be it congenital, iatrogenic, or traumatic. Intrathoracic meningoceles are rare and are most commonly associated with neurofibromatosis. When indicated, surgical management of symptomatic thoracic meningocele is aimed at decreasing the size of the meningocele, which can be accomplished by a variety of procedures.

CASE DESCRIPTION

A 59-year-old woman with neurofibromatosis type 1 and a known thoracic meningocele was initially managed conservatively. However, she developed syringomyelia and subsequently became symptomatic from the syrinx. She was ultimately treated successfully with ventriculoperitoneal shunt. Shunting resulted in complete resolution of the syrinx, while the thoracic meningocele remained stable in size.

CONCLUSIONS

Ventriculoperitoneal shunt can be used to successfully treat a symptomatic syrinx in a patient with an asymptomatic thoracic meningocele. Alterations in normal cerebrospinal fluid flow dynamics from the thoracic meningocele likely contributed to the development of syringomyelia in this patient.

Characterization of intrathecal cerebrospinal fluid geometry and dynamics in cynomolgus monkeys (macaca fascicularis) by magnetic resonance imaging

Recent advancements have been made toward understanding the diagnostic and therapeutic potential of cerebrospinal fluid (CSF) and related hydrodynamics. Increased understanding of CSF dynamics may lead to improved detection of central nervous system (CNS) diseases and optimized delivery of CSF based CNS therapeutics, with many proposed therapeutics hoping to successfully treat or cure debilitating neurological conditions. Before significant strides can be made toward the research and development of interventions designed for human use, additional research must be carried out with representative subjects such as non-human primates (NHP). This study presents a geometric and hydrodynamic characterization of CSF in eight cynomolgus monkeys (Macaca fascicularis) at baseline and two-week follow-up.

Results showed that CSF flow along the entire spine was laminar with a Reynolds number ranging up to 80 and average Womersley number ranging from 4.1–7.7. Maximum CSF flow rate occurred ~25 mm caudal to the foramen magnum. Peak CSF flow rate ranged from 0.3–0.6 ml/s at the C3-C4 level. Geometric analysis indicated that average intrathecal CSF volume below the foramen magnum was 7.4 ml. The average surface area of the spinal cord and dura was 44.7 and 66.7 cm² respectively. Subarachnoid space cross-sectional area and hydraulic diameter ranged from 7–75 mm² and 2–3.7 mm, respectively. Stroke volume had the greatest value of 0.14 ml at an axial location corresponding to C3-C4.

Subarachnoid Trabeculae: A Comprehensive Review of Their Embryology, Histology, Morphology, and Surgical Significance

INTRODUCTION

Brain is suspended in cerebrospinal fluid (CSF)-filled subarachnoid space by subarachnoid trabeculae (SAT), which are collagen-reinforced columns stretching between the arachnoid and pia maters. Much neuroanatomic research has been focused on the subarachnoid cisterns and arachnoid matter but reported data on the SAT are limited. This study provides a comprehensive review of subarachnoid trabeculae, including their embryology, histology, morphologic variations, and surgical significance.

METHODS

A literature search was conducted with no date restrictions in PubMed, Medline, EMBASE, Wiley Online Library, Cochrane, and Research Gate. Terms for the search included but were not limited to subarachnoid trabeculae, subarachnoid trabecular membrane, arachnoid mater, subarachnoid trabeculae embryology, subarachnoid trabeculae histology, and morphology. Articles with a high likelihood of bias, any study published in nonpopular journals (not indexed in PubMed or MEDLINE), and studies with conflicting data were excluded.

RESULTS

A total of 1113 articles were retrieved. Of these, 110 articles including 19 book chapters, 58 original articles, 31 review articles, and 2 case reports met our inclusion criteria.

CONCLUSIONS

SAT provide mechanical support to neurovascular structures through cell-to-cell interconnections and specific junctions between the pia and arachnoid maters. They vary widely in appearance and configuration among different parts of the brain. The complex network of SAT is inhomogeneous and mainly located in the vicinity of blood vessels. Microsurgical procedures should be performed with great care, and sharp rather than blunt trabecular dissection is recommended because of the close relationship to neurovascular structures. The significance of SAT for cerebrospinal fluid flow and hydrocephalus is to be determined.