Dynamic visualization of arachnoid adhesions in a patient with idiopathic syringomyelia using high-resolution cine magnetic resonance imaging at 3T

The leptomeninges as a critical organ for normal CNS development and function: First patient and public involved systematic review of arachnoiditis (chronic meningitis)

BACKGROUND & IMPORTANCE

This patient and public-involved systematic review originally focused on arachnoiditis, a supposedly rare "iatrogenic chronic meningitis" causing permanent neurologic damage and intractable pain. We sought to prove disease existence, causation, symptoms, and inform future directions. After 63 terms for the same pathology were found, the study was renamed Diseases of the Leptomeninges (DLMs). We present results that nullify traditional clinical thinking about DLMs, answer study questions, and create a unified path forward.

METHODS

The prospective PRISMA protocol is published at Arcsology.org. We used four platforms, 10 sources, extraction software, and critical review with ≥2 researchers at each phase. All human sources to 12/6/2020 were eligible for qualitative synthesis utilizing R. Weekly updates since cutoff strengthen conclusions.

RESULTS

Included were 887/14286 sources containing 12721 DLMs patients. Pathology involves the subarachnoid space (SAS) and pia. DLMs occurred in all countries as a contributor to the top 10 causes of disability-adjusted life years lost, with communicable diseases (CDs) predominating. In the USA, the ratio of CDs to iatrogenic causes is 2.4:1, contradicting arachnoiditis literature. Spinal fusion surgery comprised 54.7% of the iatrogenic category, with rhBMP-2 resulting in 2.4x more DLMs than no use (p<0.0001). Spinal injections and neuraxial anesthesia procedures cause 1.1%, and 0.2% permanent DLMs, respectively. Syringomyelia, hydrocephalus, and arachnoid cysts are complications caused by blocked CSF flow. CNS neuron death occurs due to insufficient arterial supply from compromised vasculature and nerves traversing the SAS. Contrast MRI is currently the diagnostic test of choice. Lack of radiologist recognition is problematic.

DISCUSSION & CONCLUSION

DLMs are common. The LM clinically functions as an organ with critical CNS-sustaining roles involving the SAS-pia structure, enclosed cells, lymphatics, and biologic pathways. Cases involve all specialties. Causes are numerous, symptoms predictable, and outcomes dependent on time to treatment and extent of residual SAS damage. An international disease classification and possible treatment trials are proposed.

Theco-thecal bypass technique elucidating a novel procedure and perspective on treatment of post-arachnoiditis syringomyelia: A case report

BACKGROUND

Post-arachnoiditis syringomyelia is a condition in which there is an intraspinal cerebrospinal fluid (CSF) blockade due to arachnoidal adhesions and bands. Although many of the techniques currently in use, namely, the theco-peritoneal, syringo-pleural, syringo-peritoneal, and syringo-subarachnoid shunts, are effective, the results are often variable.

CASE SUMMARY

A 36-year-old man with a past history of pulmonary tuberculosis, presented with progressive paraesthesia in the feet and progressive paraparesis along with constipation, difficulty in micturition, and decreased libido. He was bedridden a month before presentation. Magnetic resonance imaging revealed a dorsal multiloculated syrinx from D3-D10 vertebral levels. He underwent a D1-2 to D11 theco-thecal shunt bilaterally to abolish the CSF gradient across the level of the syrinx. There was no direct surgical handling of the spinal cord involved. At the 15-mo follow up, the patient had significant improvement in his symptoms and function.

CONCLUSION

We present a novel technique aimed at correcting the primary cause of a post-arachnoiditis syrinx, the subarachnoid cerebrospinal flow obstruction or block, which we believe is simple and effective, involves minimal handling of the normal neural structures, and attempts to restore the physiology of CSF flow across the obstruction, with favorable clinical results.

Pulsatile cerebrospinal fluid dynamics in Chiari I malformation syringomyelia: Predictive value in posterior fossa decompression and insights into the syringogenesis

Background:

Pathophysiological mechanisms underlying the syringomyelia associated with Chiari I malformation (CM-1) are still not completely understood, and reliable predictors of the outcome of posterior fossa decompression (PFD) are lacking accordingly. The reported prospective case-series study aimed to prove the existence of a pulsatile, biphasic systolic–diastolic cerebrospinal fluid (CSF) dynamics inside the syrinx associated with CM-1 and to assess its predictive value of patients' outcome after PFD. Insights into the syringogenesis are also reported.

Methods:

Fourteen patients with symptomatic CM-1 syringomyelia underwent to a preoperative neuroimaging study protocol involving conventional T1/T2 and cardiac-gated cine phase-contrast magnetic resonance imaging sequences. Peak systolic and diastolic velocities were acquired at four regions of interest (ROIs): syrinx, ventral, and dorsal cervical subarachnoid space and foramen magnum region. Data were reported as mean ± standard deviation. After PFD, the patients underwent a scheduled follow-up lasting 3 years. One-way analysis of variance with Bonferroni Post hoc test of multiple comparisons was performed P was <0.001.

Results:

All symptoms but atrophy and spasticity improved. PFD caused a significant velocity changing of each ROI. Syrinx and premedullary cistern velocities were found to be decreased within the 1^st month after PFD (<0.001). A caudad and cephalad CSF jet flow was found inside the syrinx during systole and diastole, respectively.

Conclusion:

Syrinx and premedullary cistern velocities are related to an early improvement of symptoms in patients with CM-1 syringomyelia who underwent PFD. The existence of a biphasic pulsatile systolic–diastolic CSF pattern inside the syrinx validates the “transmedullary” theory about the syringogenesis.

Ex-vivo quantification of ovine pia arachnoid complex biomechanical properties under uniaxial tension

Background

The pia arachnoid complex (PAC) is a cerebrospinal fluid-filled tissue conglomerate that surrounds the brain and spinal cord. Pia mater adheres directly to the surface of the brain while the arachnoid mater adheres to the deep surface of the dura mater. Collagen fibers, known as subarachnoid trabeculae (SAT) fibers, and microvascular structure lie intermediately to the pia and arachnoid meninges. Due to its structural role, alterations to the biomechanical properties of the PAC may change surface stress loading in traumatic brain injury (TBI) caused by sub-concussive hits. The aim of this study was to quantify the mechanical and morphological properties of ovine PAC.

Methods

Ovine brain samples (n = 10) were removed from the skull and tissue was harvested within 30 min post-mortem. To access the PAC, ovine skulls were split medially from the occipital region down the nasal bone on the superior and inferior aspects of the skull. A template was used to remove arachnoid samples from the left and right sides of the frontal and occipital regions of the brain. 10 ex-vivo samples were tested with uniaxial tension at 2 mm s⁻¹, average strain rate of 0.59 s⁻¹, until failure at < 5 h post extraction. The force and displacement data were acquired at 100 Hz. PAC tissue collagen fiber microstructure was characterized using second-harmonic generation (SHG) imaging on a subset of n = 4 stained tissue samples. To differentiate transverse blood vessels from SAT by visualization of cell nuclei and endothelial cells, samples were stained with DAPI and anti-von Willebrand Factor, respectively. The Mooney-Rivlin model for average stress–strain curve fit was used to model PAC material properties.

Results

The elastic modulus, ultimate stress, and ultimate strain were found to be 7.7 ± 3.0, 2.7 ± 0.76 MPa, and 0.60 ± 0.13, respectively. No statistical significance was found across brain dissection locations in terms of biomechanical properties. SHG images were post-processed to obtain average SAT fiber intersection density, concentration, porosity, tortuosity, segment length, orientation, radial counts, and diameter as 0.23, 26.14, 73.86%, 1.07 ± 0.28, 17.33 ± 15.25 µm, 84.66 ± 49.18°, 8.15%, 3.46 ± 1.62 µm, respectively.

Conclusion

For the sizes, strain, and strain rates tested, our results suggest that ovine PAC mechanical behavior is isotropic, and that the Mooney-Rivlin model is an appropriate curve-fitting constitutive equation for obtaining material parameters of PAC tissues.

Cine balanced fast field echo magnetic resonance imaging of canine spinal arachnoid diverticulae pulsation

Canine spinal arachnoid diverticulae (SAD) are characterised by focal cerebrospinal fluid dilatations within the subarachnoid space, most commonly associated with nonpainful paresis and ataxia secondary to chronic compressive myelopathy. Numerous imaging techniques have been described for diagnosis of this condition, including myelography, computed tomography myelography, and magnetic resonance imaging (MRI). The present retrospective study investigated the utility of cine balanced fast field echo (cine bFFE) MRI sequences in measuring pulsatile flow in 12 dogs with SAD. The secondary aim was to determine the prevalence and location of syringes in relation to SAD, as the co-occurrence of these conditions has not been previously reported. The degree of SAD pulsation was calculated as the change in area per cardiac cycle on sagittal (n = 12/12) and transverse (n = 7/12) cardiac-gated cine bFFE MRI sequences. Pulsation was identified on all sequences, with a median ratio of change in SAD area of 0.14 (range, 0.10-0.27; n = 12) on sagittal cine bFFE and 0.23 (range, 0.05-0.53; n = 7) on transverse cine bFFE sequences. Significant differences between minimum and maximum SAD dimensions were identified on sagittal (P = 0.002) and transverse measurements (P = 0.018). A moderate prevalence of syringomyelia was identified (n = 6/12; 50%) on T2W sequences, occurring both cranial (n = 4/12; 33%) and caudal (n = 2/12; 17%) to the SAD. These results support the ability of cine bFFE sequences to identify dynamic pulsation of canine SAD. This technique is currently limited by banding artifacts and its inability to quantify flow velocity and abnormal flow jets.

Arachnoid web of the spine: a systematic literature review

OBJECTIVE

An arachnoid web of the spine (AWS) is a rare and oftentimes challenging lesion to diagnose, given its subtle radiographic findings. However, when left untreated, this lesion can have devastating effects on a patient's neurological function. To date, only limited case reports and series have been published on this topic. In this study, the authors sought to better describe this lesion, performing a systematic literature review and including 2 cases from their institution's experience.

METHODS

A systematic literature search was performed in September 2018 that queried Ovid MEDLINE (1946-2018), PubMed (1946-2018), Wiley Cochrane Library: Central Register of Controlled Trials (1898-2018), and Thompson Reuters Web of Science: Citation Index (1900-2018), per PRISMA guidelines. Inclusion criteria specified all studies and case reports of patients with an AWS in which any relevant surgery types were considered and applied. Studies on arachnoid cysts and nonhuman populations, and those that did not report patient treatments or outcomes were excluded from the focus review.

RESULTS

A total of 19 records and 2 patients treated by the senior authors were included in the systematic review, providing a total of 43 patients with AWS. The mean age was 52 years (range 28-77 years), and the majority of patients were male (72%, 31/43). A syrinx was present in 67% (29/43) of the cases. All AWSs were located in the thoracic spine, and all but 2 (95%) were located dorsally (1 ventrally and 1 circumferentially). Weakness was the most frequently reported symptom (67%, 29/43), followed by numbness and/or sensory loss (65%, 28/43). Symptoms predominated in the lower extremities (81%, 35/43). It was found that nearly half (47%, 20/43) of patients had been experiencing symptoms for 1 year or longer before surgical intervention was performed, and 35% (15/43) of reports stated that symptoms were progressive in nature. The most commonly used surgical technique was a laminectomy with intradural excision of the arachnoid web (86%, 36/42). Following surgery, 91% (39/43) of patients had reported improvement in their neurological symptoms. The mean follow-up was 9.2 months (range 0-51 months).

CONCLUSIONS

AWS of the spine can be a debilitating disease of the spine with no more than an indentation of the spinal cord found on advanced imaging studies. The authors found this lesion to be reported in twice as many males than females, to be associated with a syrinx more than two-thirds of the time, and to only have been reported in the thoracic spine; over 90% of patients experienced improvement in their neurological function following surgery.

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.

Imaging Appearance of Advanced Chronic Adhesive Arachnoiditis: A Retrospective Review

OBJECTIVE

Chronic adhesive arachnoiditis (CAA) is rare and has potentially devastating clinical consequences. The objective of this article is to review the clinical features of CAA and describe its appearance on imaging, to increase radiologists' awareness of this challenging diagnosis.

MATERIALS AND METHODS

Twenty-nine cases of advanced CAA seen at our institution over 18 years (1995-2013) were retrospectively reviewed. Chart review was performed, with attention given to data on clinical presentation, suspected cause, and interventions performed. All patients underwent MRI, and seven patients also underwent CT myelography. Clinical and imaging features were evaluated and categorized.

RESULTS

The 29 patients ranged in age from 23 to 96 years and included 11 women and 18 men. Suspected underlying causative factors included trauma (n = 10), prior surgery (n = 9), nontraumatic subarachnoid hemorrhage (n = 7), infection (n = 3), myelography with iophendylate used as contrast medium (n = 1), Guillain-Barré syndrome (n = 1), ankylosing spondylitis (n = 1), and unknown causes (n = 1). Imaging characteristics include loculated CSF collections (n = 23), nerve root clumping, enhancement, and displacement (n = 15), cord swelling with increased T2 signal (n = 12), arachnoid septations (n = 11), cord atrophy (n = 6), syrinx (n = 5), and intrathecal calcifications (n = 3). Ten patients underwent surgical procedures, and most had only brief clinical improvement.

CONCLUSION

CAA is a rare cause of devastating neurologic symptoms and chronic pain. The imaging features of CAA range from subtle to severe. Advanced arachnoiditis can present with spinal cord swelling and syrinx formation, which can mimic other disease processes. Inclusion of advanced CAA in the differential diagnosis can prevent unnecessary interventions.

Idiopathic intradural dorsal thoracic arachnoid cysts: A case series and review of the literature

BACKGROUND

Spinal intradural arachnoid cysts (SIAC) are cerebrospinal fluid (CSF) filled sacs formed by arachnoid membranes and may be either idiopathic or acquired. Idiopathic cysts represent a separate entity and their aetiology remains uncertain. By far the most difficult differential diagnosis is distinguishing between idiopathic anterior spinal cord herniation (IASCH) and dorsal thoracic intradural arachnoid cysts (TIAC), due to their similarity in radiological appearance. Cine-mode (SSFP) is emerging as a novel technique in the diagnosis and operative planning of SIAC.

METHOD

Retrospective analysis of patients with idiopathic TIACs that were surgically managed at Royal North Shore Hospital and North Shore Private Hospital between November 2000 and November 2015.

RESULTS

Ten patients were included in this study. Age ranged from 20 to 77years with a mean age of 60years and a female preponderance. The most common clinical features were progressive gait ataxia and lower limb myelopathy. Radicular pain tends to improve following surgery, however gait ataxia may not.

DISCUSSION

While there are circumstances in which the distinction between dorsal thoracic intradural arachnoid cysts and idiopathic anterior spinal cord herniation are radiologically obvious, in cases where the appearances are less clear, cine-mode SSFP MRI imaging can provide an invaluable tool to differentiate these pathologies and lead the clinician towards the correct diagnosis and management. The mainstay of surgical management for dorsal TIACs is laminectomy and cyst excision or fenestration. Surgery for gait ataxia should be aimed towards preventing deterioration, while maintaining the potential for symptomatic improvement, whereas surgery for radicular pain should be curative.

[Treatment of syringomyelia associated with adhesive arachnoiditis]

The prevalence of syringomyelia (SM) caused by adhesive arachnoiditis (AA) is 2 to 4 cases per 100000 population. Surgical treatment of this pathology usually includes implantation of shunts into the cyst cavity or opening and drainage of the cavity. In this case, SM continues to progress in 72-100% of patients. Unsatisfactory outcomes of this surgical approach necessitate searching for other treatment options.

PURPOSE

To define the optimal amount of surgery for SM associated with AA and the criteria for assessment of surgery outcomes.

MATERIAL AND METHODS

The authors treated 47 SM patients in the period from 2010 to 2015. Of these, 34 (72.3%) patients underwent surgery; a total of 40 operations were performed. The patients' age ranged from 18 to 64 years (mean, 43.5 years). Tethering of the spinal cord was eliminated in 25 patients; 9 patients underwent cyst shunting.

RESULTS

Among operated patients, 5 patients had grade 1 arachnopathy, 13 patients had grade 2 arachnopathy, 12 patients had grade 3 arachnopathy, and 4 patients had grade 4 arachnopathy. The minimal postoperative follow-up period was 11 months. After shunting, the condition improved in 8 of 9 patients; in 7 patients, the condition returned to the baseline level within the first postoperative year; in 6 (66.7%) of these patients, the disease continued to progress. After surgical release of spinal cord tethering, satisfactory long-term results were achieved in 13 (86.6%) patients with grade 1-2 arachnopathy. In 3 (50%) patients with grade 3 arachnopathy, the condition was stabilized. Among patients with grade 4 arachnopathy, progression of the disease was stopped in 1 patient; the condition worsened in 2 (50%) patients. Among all the operated patients, complications developed in 7 patients. There were no lethal outcomes.

CONCLUSIONS

In grade 1-2 arachnopathy, progression of SM after release of spinal cord tethering occurs only in 13.4% of patients. Therefore, release of spinal cord tethering is recommended for these patients. In grade 3-4 arachnopathy, the rate of relapse after this surgery is more than 80%. Therefore, given the simplicity and a lower risk of complications of cyst shunting, this procedure is advisable for these patients.

Syringomyelia secondary to "occult" dorsal arachnoid webs: Report of two cases with review of literature

In a certain group of patients with syringomyelia, even with the advent of sophisticated magnetic resonance imaging (MRI), no associated abnormality or cerebrospinal fluid (CSF) block is easily identified. This type of syringomyelia is often termed idiopathic. Current literature has less than 10 reports of arachnoid webs to be the causative factor. We present our experience in the management of two cases of syringomyelia secondary to arachnoid webs. Both our patients presented with progressive neurological deterioration with MRI scans demonstrating cervical/thoracic syrinx without Chiari malformation or low-lying cord. There was no history of previous meningitis or trauma. Both patients underwent myelography that demonstrated dorsal flow block implying CSF obstruction. Cord displacement/change in caliber was also noted and this was not evident on MRI scans. Both patients underwent thoracic laminectomy. After opening the dura, thickened/abnormal arachnoid tissue was found that was resected thus widely communicating the dorsal subarachnoid space. Postoperatively at 6 months, both patients had significant symptomatic improvement with follow-up MRI scans demonstrating significant resolution of the syrinx. In patients with presumed idiopathic syringomyelia, imaging studies should be closely inspected for the presence of a transverse arachnoid web. We believe that all patients with idiopathic symptomatic syringomyelia should have MRI CSF flow studies and/or computed tomography (CT) myelography to identify such arachnoid abnormalities that are often underdiagnosed. Subsequent surgery should be directed at the establishment of normal CSF flow by laminectomy and excision of the offending arachnoid tissue.

Fast dynamic imaging technique to identify obstructive lesions in the CSF space: report of 2 cases

Disorders of CSF dynamics such as syringomyelia and obstructive hydrocephalus can be caused by thin mobile obstructive lesions not visible on traditional MRI sequences. New imaging techniques with balanced steady-state free precession (bSSFP) and dynamic imaging with bSSFP cine allow visualization of these pulsatile structures within the CSF space. The authors present 2 cases involving pediatric patients-one who developed presumed idiopathic syringomyelia and one with presumed communicating hydrocephalus in association with Pfeiffer syndrome-who harbored thin dynamic obstructive lesions seen on bSSFP cine studies using 1.5-T MRI. In combination with traditional CSF cine studies and bSSFP, bSSFP cine sequence was able to detect dynamic membranous adhesions not seen on traditional MRI sequences. These previously undetectable lesions on traditional MRI sequences were the etiology of CSF obstruction, and tailored surgical approaches were performed to avoid shunting in both patients. These reports demonstrate the clinical utility for using these novel imaging tools for the detection of thin adhesions and dynamic lesions in the central nervous system. Balanced SSFP cine sequences can supplement conventional MR modalities to identify these otherwise poorly visualized lesions responsible for presumed communicating hydrocephalus or idiopathic syringomyelia.

Familial adhesive arachnoiditis associated with syringomyelia

Adhesive arachnoiditis is a rare condition, often complicated by syringomyelia. This pathologic entity is usually associated with prior spinal surgery, spinal inflammation or infection, and hemorrhage. The usual symptoms of arachnoiditis are pain, paresthesia, and weakness of the low extremities due to the nerve entrapment. A few cases have had no obvious etiology. Previous studies have reported one family with multiple cases of adhesive arachnoiditis. We report a second family of Belgian origin with multiple cases of arachnoiditis and secondary syringomyelia in the affected individuals.

Dorsal spinal arachnoid web diagnosed with the quantitative measurement of cerebrospinal fluid flow on magnetic resonance imaging

An arachnoid web is an abnormal formation of the arachnoid membrane in the spinal subarachnoid space that blocks CSF flow and causes syringomyelia. Although the precise mechanism of syrinx formation is unknown, dissection of the arachnoid web shrinks the syrinx and improves symptoms. Precisely determining the location of the arachnoid web is difficult preoperatively, however, because the fine structure generally cannot be visualized in usual MRI sequences. In this report the authors describe 2 cases of arachnoid web in which the web was preoperatively identified using quantitative CSF flow analysis of MRI. By analyzing cardiac-gated phase-contrast cine-mode MRI in multiple axial planes, the authors precisely localized the obstruction of CSF flow on the dorsal side of the spinal cord in both patients. This technique also revealed a 1-way valve-like function of the arachnoid webs. Imaging led to the early diagnosis of myelopathy related to the derangement of CSF flow and allowed the authors to successfully excise the webs through limited surgical exposure.

Assessment of cerebellar pulsation in dogs with and without Chiari-like malformation and syringomyelia using cardiac-gated cine magnetic resonance imaging

Canine Chiari-like malformation (CM) is characterised by herniation of part of the cerebellum through the foramen magnum. In humans with Chiari type I malformation (CM-I), abnormal pulsation of the cerebellum during the cardiac cycle has been documented and is pivotal to theories for the pathogenesis of syringomyelia (SM). In this retrospective study, cardiac-gated cine balanced fast field echo (bFEE) magnetic resonance imaging (MRI) was used to assess pulsation of the brain in dogs and to objectively measure the degree of cerebellar pulsation with the neck in a flexed position. Overall, 17 Cavalier King Charles Spaniels (CKCS) with CM, including eight with SM and nine without SM, were compared with six small breed control dogs. Linear regions of interest were generated for the length of cerebellar herniation from each phase of the cardiac cycle and the degree of cerebellar pulsation was subsequently calculated. Age, bodyweight and angle of neck flexion were also compared. CKCS with CM and SM had significantly greater pulsation of the cerebellum than control dogs (P=0.003) and CKCS with CM only (P=0.031). There was no significant difference in age, bodyweight and angle of neck flexion between the three groups. Cardiac-gated cine bFEE MRI permitted the dynamic visualisation of cerebellar pulsation in dogs. These findings support the current theories regarding the pathogenesis of SM secondary to CM and further highlight the similarities between canine CM and human CM-I.

[Spinal cord injury and syringomyelia]

Spinal cord injuries often occur in cases of multiple trauma, can occur alone or in combination with concomitant injuries and are mostly associated with high morbidity and mortality. They often result in lifelong impairment and need for medical care. Radiologic diagnostics are crucial in the acute setting as well as in the long-term treatment of spinal cord injuries. Besides an overview of diagnostic and therapeutic management, typical magnetic resonance imaging (MRI) findings in the acute and chronic stages of spinal cord injuries are presented in this article. Post-traumatic syringomyelia can even develop years after the initial injury of the spine or spinal cord. As syringomyelia can also occur in association with tumors, developmental anomalies and also idiopathically, a thorough MRI diagnostic is essential especially in any case of newly diagnosed syringomyelia.

A coupled hydrodynamic model of the cardiovascular and cerebrospinal fluid system

Coupling of the cardiovascular and cerebrospinal fluid (CSF) system is considered to be important to understand the pathophysiology of cerebrovascular and craniospinal disease and intrathecal drug delivery. A coupled cardiovascular and CSF system model was designed to examine the relation of spinal cord (SC) blood flow (SCBF) and CSF pulsations along the spinal subarachnoid space (SSS). A one-dimensional (1-D) cardiovascular tree model was constructed including a simplified SC arterial network. Connection between the cardiovascular and CSF system was accomplished by a transfer function based on in vivo measurements of CSF and cerebral blood flow. A 1-D tube model of the SSS was constructed based on in vivo measurements in the literature. Pressure and flow throughout the cardiovascular and CSF system were determined for different values of craniospinal compliance. SCBF results indicated that the cervical, thoracic, and lumbar SC each had a signature waveform shape. The cerebral blood flow to CSF transfer function reproduced an in vivo-like CSF flow waveform. The 1-D tube model of the SSS resulted in a distribution of CSF pressure and flow and a wave speed that were similar to those in vivo. The SCBF to CSF pulse delay was found to vary a great degree along the spine depending on craniospinal compliance and vascular anatomy. The properties and anatomy of the SC arterial network and SSS were found to have an important impact on pressure and flow and perivascular fluid movement to the SC. Overall, the coupled model provides predictions about the flow and pressure environment in the SC and SSS. More detailed measurements are needed to fully validate the model.

Amelioration of caudal thoracic syringohydromyelia following surgical management of an adjacent arachnoid cyst

A nine-year-old male, neutered, pug was presented for investigation of progressive ambulatory paraparesis and pelvic limb ataxia of three months' duration. Magnetic resonance imaging was suggestive of caudal thoracic syringohydromyelia with an adjacent intradural arachnoid cyst. The cyst was marsupialised following dorsal laminectomy. Neurological status had improved 10 weeks following surgery when repeat magnetic resonance imaging revealed reduced spinal cord compression both as a result of resolution of the cyst and reduction in size of the syringohydromyelia. At 17 months following surgery, the dog showed further improvements in neurological status, exhibiting mild pelvic limb ataxia and proprioceptive deficits. Improved cerebrospinal fluid flow following surgery may have played a role in the improvement in both conditions. The presence of syringohydromyelia in this context does not preclude a favourable clinical outcome following surgical management.