Progressive post-traumatic cystic and non-cystic myelopathy

Spinal cord tethering and syringomyelia after trauma: impact of age and surgical outcome

Posttraumatic spinal cord tethering and syringomyelia frequently lead to progressive neurological loss. Although several studies demonstrated favourable outcome following spinal cord detethering with/without shunting, additional research is required as no clear consensus exists over the ideal treatment strategy and knowledge about prognostic demographic determinants is currently limited. In this investigation, we retrospectively investigated 67 patients (56 men, 11 women) who were surgically treated and followed for symptomatic spinal cord tethering and syringomyelia from 2012 to 2022 at our center. Age (B-coefficient 0.396) and severity of trauma to the spinal cord (B-coefficient - 0.462) have been identified as independent predictors for the rate of development of symptomatic spinal cord tethering and syringomyelia (p < 0.001). Following untethering surgery including expansion duraplasty with/without shunting, 65.9% of patients demonstrated an improvement of neurological loss (p < 0.001) whereas 50.0% of patients displayed amelioration of spasticity and/or neuropathic pain (p < 0.001). Conclusively, active screening for symptomatic spinal cord tethering and syringomyelia, particularly in younger patients with severe spinal trauma, is crucial as surgical untethering with/without shunting is able to achieve favourable clinical outcomes. This knowledge may enable clinicians to tailor treatment strategies in spinal cord injury patients suffering from progressive neurological loss towards a more optimal and personalized patient care.

Surgical Management of Lumbar Adhesive Arachnoiditis Postmeningitis: A Bermuda Triangle?—Case Report and Review of Literature

Spinal arachnoiditis can occur as a delayed sequel of meningitis. Cerebrospinal fluid flow disturbances and adhesive loculations can cause cord compression and traction on roots causing the symptoms. The surgical treatment of this condition is often considered a limited option, because of the high chances of recurrence of symptoms and adhesions, often considered as surgical failure. Here, we report a patient with extensive lumbar–sacral adhesive arachnoiditis successfully treated with limited adhesiolysis under neuromonitoring and cystoperitoneal shunt placement.

Long-term outcome following surgical treatment of posttraumatic tethered cord syndrome: a retrospective population-based cohort study

STUDY DESIGN

Retrospective population-based cohort study.

OBJECTIVE

To investigate the long-term outcome following surgery for posttraumatic spinal cord tethering (PSCT).

SETTING

Publicly funded tertiary care center.

METHODS

Patients surgically treated for PSCT between 2005-2020 were identified and included. No patients were excluded or lost to follow-up. Medical records and imaging data were retrospectively reviewed.

RESULTS

Seventeen patients were included. Median age was 52 (23-69) years and 7 (41%) were female. PSCT was diagnosed at a median of 5.0 (0.6-27) years after the initial trauma. Motor deficit was the most common neurological manifestation (71%), followed by sensory deficit (53%), spasticity (53%), pain (41%) and gait disturbance (24%). Median follow-up time was 5.1 (0.7-13) years. Fifteen patients (88%) showed satisfactory results following untethering, defined as improvement or halted progression of one or more of the presenting symptoms. Treatment goals were met for motor symptoms in 92%, sensory loss in 100%, spasticity in 100%, gait disturbance in 100% and pain in 86%. Statistically, a significant improvement in motor deficit (p = 0.031) and syrinx decrease (p = 0.004) was also seen. A postoperative complication occurred in four patients: three cases of cerebrospinal fluid leakage and one postoperative hematoma. Two patients showed a negative surgical outcome: 1 with increased neck pain and 1 with left arm weakness following the postoperative hematoma.

CONCLUSION

Surgical treatment of PSCT results in improved neurological function or halted neurological deterioration in the vast majority of patients.

Development of pre-syrinx state and syringomyelia following a minor injury: a case report

Background

A generally accepted rule is that posttraumatic syringomyelia (PTS) results from spinal cord injury (SCI).

Case presentation

Here, we report the development of syringomyelia without SCI in a 54-year-old Caucasian man following a mild motor vehicle accident. The computed tomography on admission excluded an injury of the spine. Because of neck and back pain, magnetic resonance imaging was performed on day 3 post-injury and demonstrated minimal changes from a ligamentous strain at the cervicothoracic transition. Any traumatic affection of the bone, vertebral discs, intraspinal compartment, or spinal cord were excluded. Some limb weakness and neurogenic bladder dysfunction started manifesting within the following weeks. Repeated MRIs following the accident demonstrated arachnoid adhesions at the C1–2 level and spinal cord edema equivalent to a pre-syrinx state at 12 months and syrinx formation at 24 months. Because of further deterioration, decompression was performed at 36 months.

Conclusions

We conclude that even after a minor trauma PTS can occur and that medullary edema (pre-syrinx state) may precede syrinx formation.

Treatment of posttraumatic syringomyelia: evidence from a systematic review

Background

Following spinal cord injury (SCI), the routine use of magnetic resonance imaging (MRI) resulted in an incremental diagnosis of posttraumatic syringomyelia (PTS). However, facing four decades of preferred surgical treatment of PTS, no clear consensus on the recommended treatment exists. We review the literature on PTS regarding therapeutic strategies, outcomes, and complications.

Methods

We performed a systematic bibliographic search on (“spinal cord injuries” [Mesh] AND “syringomyelia” [Mesh]). English language literature published between 1980 and 2020 was gathered, and case reports and articles examining syrinx due to other causes were excluded. The type of study, interval injury to symptoms, severity and level of injury, therapeutic procedure, duration of follow-up, complications, and outcome were recorded.

Results

Forty-three observational studies including 1803 individuals met the eligibility criteria. The time interval from SCI to the diagnosis of PTS varied between 42 and 264 months. Eighty-nine percent of patients were treated surgically (n = 1605) with a complication rate of 26%. Symptoms improved in 43% of patients postoperatively and in 2% treated conservatively. Stable disease was documented in 50% of patients postoperatively and in 88% treated conservatively. The percentage of deterioration was similar (surgery 16%, 0.8% dead; conservative 10%). Detailed analysis of surgical outcome with regard to symptoms revealed that pain, motor, and sensory function could be improved in 43 to 55% of patients while motor function deteriorated in around 25%. The preferred methods of surgery were arachnoid lysis (48%) and syrinx drainage (31%).

Conclusion

Even diagnosing PTS early in its evolution with MRI, to date, no satisfactory standard treatment exists, and the present literature review shows similar outcomes, regardless of the treatment modality. Therefore, PTS remains a neurosurgical challenge. Additional research is required using appropriate study designs for improving treatment options.

Cerebrospinal fluid levels of GFAP and pNF-H are elevated in patients with chronic spinal cord injury and neurological deterioration

BACKGROUND

Years after a traumatic spinal cord injury (SCI), a subset of patients may develop progressive clinical deterioration due to intradural scar formation and spinal cord tethering, with or without an associated syringomyelia. Meningitis, intradural hemorrhages, or intradural tumor surgery may also trigger glial scar formation and spinal cord tethering, leading to neurological worsening. Surgery is the treatment of choice in these chronic SCI patients.

OBJECTIVE

We hypothesized that cerebrospinal fluid (CSF) and plasma biomarkers could track ongoing neuronal loss and scar formation in patients with spinal cord tethering and are associated with clinical symptoms.

METHODS

We prospectively enrolled 12 patients with spinal cord tethering and measured glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase L1 (UCH-L1), and phosphorylated Neurofilament-heavy (pNF-H) in CSF and blood. Seven patients with benign lumbar intradural tumors and 7 patients with cervical radiculopathy without spinal cord involvement served as controls.

RESULTS

All evaluated biomarker levels were markedly higher in CSF than in plasma, without any correlation between the two compartments. When compared with radiculopathy controls, CSF GFAP and pNF-H levels were higher in patients with spinal cord tethering (p ≤ 0.05). In contrast, CSF UCH-L1 levels were not altered in chronic SCI patients when compared with either control groups.

CONCLUSIONS

The present findings suggest that in patients with spinal cord tethering, CSF GFAP and pNF-H levels might reflect ongoing scar formation and neuronal injury potentially responsible for progressive neurological deterioration.

Safety and Efficacy of Syringoperitoneal Shunting with a Programmable Shunt Valve for Syringomyelia Associated with Extensive Spinal Adhesive Arachnoiditis: Technical Note

OBJECTIVE

Although syringomyelia associated with extensive spinal adhesive arachnoiditis (SAA) can be a progressive disease that has potentially devastating clinical consequences, its surgical resolution has remained poorly defined. The aim of the present study was to verify the safety and efficacy of syringoperitoneal shunting for syringomyelia associated with extensive SAA.

METHODS

The present retrospective study included 15 patients who had undergone syringoperitoneal shunting with a programmable shunt valve for the diagnosis of syringomyelia associated with extensive SAA from October 2012 to June 2018. The shunt pressure was appropriately adjusted according to the postoperative sequential clinical condition and change in syringomyelia evaluated using magnetic resonance imaging. The average postoperative follow-up duration was 32.7 months.

RESULTS

No surgery-related complications such as shunt dysfunction or infection occurred during the follow-up period, except for 2 patients with minor issues with the shunt tube. The average shunt pressure at the last follow-up examination was 4.5 cm H₂O. The findings from the clinical assessment suggested that the average grade on the sensory pain scale was 2.9 before surgery and had improved significantly to 2.5 at the most recent follow-up examination. Radiological analysis suggested that improvement of syringomyelia was noted in 14 of the 15 patients (93.3%), with no cases of radiological aggravation. No recurrence of syringomyelia developed during the follow-up period in the present study.

CONCLUSION

Syringoperitoneal shunting with a programmable shunt valve was safe and effective for clinical control of syringomyelia associated with extensive SAA. Long-term follow-up is mandatory to monitor for shunt dysfunction and mechanical trouble.

Canine Snake-Eye Myelopathy: Clinical, Magnetic Resonance Imaging, and Pathologic Findings in Four Cases

Intramedullary signal change (ISC) is a non-specific finding that is frequently observed on magnetic resonance imaging (MRI) examinations of the canine spinal cord. ISC can represent a variety of primary pathological processes such as neoplasms or myelitides or secondary changes such as edema, cysts, gliosis, or myelomalacia. An unusual phenotype of ISC is the “snake-eye” myelopathy (SEM), which refers to bilaterally symmetric T2 hyperintensities preferentially affecting the ventral horn gray matter on transverse MR images, which resemble a pair of snake's eyes. The pathophysiology of SEM is poorly understood in humans, and this imaging finding may be associated with cervical spondylotic myelopathy, spinal cord ischemia, ossification of the posterior longitudinal ligament, amyotrophic lateral sclerosis, and Hirayama disease. Here we describe four dogs with cervical MRI examinations consistent with an SEM-like phenotype. All dogs initially presented with a central cord syndrome or tetraparesis referable to a C6-T2 neuroanatomic localization, which was attributed to disc-associated spinal cord compression in three cases, while one dog had the SEM-like phenotype with no identifiable etiology. Once the SEM-like phenotype was present on MRI examinations, dogs demonstrated insidious clinical deterioration despite therapeutic interventions. Deterioration was characterized by lower motor neuron weakness and neurogenic muscle atrophy progressing to paralysis in the thoracic limbs, while neurological functions caudal to the level of the SEM-like lesion remained largely preserved for months to years thereafter. Neuropathological features of the SEM-like phenotype include multisegmental cavitations and poliomyelomalacia of laminae VI-IX of the caudal cervical spinal cord, although the lesion evolved into pan-necrosis of gray matter with extension into the adjacent white matter in one case with an 8 years history of progressive disease. Although the pathophysiology of SEM remains unknown, the topographical distribution and appearance of lesions is suggestive of a vascular disorder. As the SEM-like phenotype was uniformly characterized by longitudinally and circumferentially extensive neuronal necrosis, results of this small case series indicate that dogs with clinical signs of central cord syndrome and the SEM-like phenotype involving the cervicothoracic intumescence on MR examinations have a poor prognosis for the preservation or recovery of thoracic limb motor function.

Chronic post-traumatic intramedullary lesions in dogs, a translational model

Objectives

Post-traumatic intramedullary myelopathies and cavitations are well described lesions following spinal cord injury (SCI) in humans and have been described in histopathological evaluations in dogs. Human intramedullary myelopathies/cavitations are associated with severe initial SCI and deterioration of clinical signs. Canine intervertebral disc extrusions share similarities with SCI in humans. In this descriptive study, magnetic resonance imaging (MRI) findings in spinal cords of dogs suffering from chronic post-traumatic myelopathies, including cavitations, are elucidated. An additional aim of the study was to compare diagnostic imaging and histopathological findings and identify similarities between human and canine chronic post-traumatic spinal cord lesions.

Methods

Thirty-seven dogs with thoracolumbar SCI and one or more 3Tesla MRI investigations more than 3 weeks after SCI were included. Extent of intramedullary lesions and particularly cavitations were evaluated and measured in sagittal and transverse MRI planes. These data were compared with clinical data.

Results

A total of 91.9% of study patients developed chronic intramedullary lesions, and 86.5% developed intramedullary cavitations. Paraplegia without deep pain perception at initial examination was significantly associated with longer chronic myelopathies/cavitations (P = 0.002/P = 0.008), and with larger maximal cross-sectional area (mCSA) of the lesions (P = 0.041/0.005). In addition, a non-ambulatory status after decompressive surgery was also associated with the development of longer intramedullary lesions/cavitations (P<0.001) and larger lesion mCSA (P<0.001/P = 0.012). All dogs with negative outcome developed myelopathies/cavitations. In the group of 21 dogs with positive outcome, 3 did not develop any myelopathies, and 5 did not develop cavitations.

Conclusions

Development of chronic intramedullary lesions/cavitations are common findings in canine SCI. Extensive chronic intramedullary lesions/cavitations reflect a severe initial SCI and negative clinical outcome. This supports the hypothesis that chronic spinal cord changes following SCI in humans share similarities with canine chronic spinal cord changes after spontaneous intervertebral disc extrusion.

Surgical Management of Syringomyelia Associated with Spinal Adhesive Arachnoiditis, a Late Complication of Tuberculous Meningitis: A Case Report

Syringomyelia associated with tuberculous meningitis is an extremely rare condition. Only a few studies have reported clinical experience with syringomyelia as a late complication of tuberculous meningitis. Twenty-six years after a tuberculous meningitis episode, a 44-year-old man presented with progressively worsening spastic paresis of the lower limbs and impaired urinary function for 2 years. Radiological examination revealed syringomyelia extending from the level of C2 to T9 and arachnoiditis with atrophy of the spinal cord between C2 and T3. We performed laminectomy from C7 to T1, dissected the arachnoid adhesion and placed a syringo-pleural shunt via keyhole myelotomy. One year after the operation, his neurological condition improved. The postoperative control magnetic resonance imaging revealed the correctly located shunt and significantly diminished syringomyelia cavities. We aim to discuss the mechanism of syrinx formation following tuberculous meningitis and to share our surgical therapeutic experience with this rare disease entity.

[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.

Intracranial hypotension after syringopleural shunting in posttraumatic syringomyelia: Case report and review of the literature

We report a case of a 45-year-old male with a syringopleural shunt who developed intracranial hypotension. The patient presented with 2 weeks history of worsening headache and back pain, on a background of having had a syringopleural shunt inserted for a thoracic posttraumatic syrinx. Computerized tomography imaging of the brain revealed bilateral subdural fluid collections. Magnetic resonance imaging appearances of spinal and intracranial pachymeningeal enhancement confirmed intracranial hypotension. We present a rare case of intracranial hypotension secondary to syringopleural shunting in a patient with posttraumatic syringomyelia.

Decorin treatment of spinal cord injury

The scarring response after a penetrant central nervous system injury results from the interaction between invading leptominingeal/pericyte-derived fibroblasts and endogenous reactive astrocytes about the wound margin. Extracellular matrix and scar-derived axon growth inhibitory molecules fill the lesion site providing both a physical and chemical barrier to regenerating axons. Decorin, a small leucine-rich chondroitin-dermatan sulphate proteoglycan expressed by neurons and astrocytes in the central nervous system, is both anti-fibrotic and anti-inflammatory and attenuates the formation and partial dissolution of established and chronic scars. Here, we discuss the potential of using Decorin to antagonise scarring in the central nervous system.

Clinical Features of Post-Traumatic Syringomyelia

Objective

The purpose of this study was to analyze the clinical manifestations, radiological findings, treatment results, and clinical significance of post-traumatic syringomyelia (PTS).

Methods

We retrospectively reviewed the medical charts of nine surgical patients with symptomatic PTS between 1992 and 2012.

Results

The most common clinical manifestation was development of new motor weakness. The mean interval between the initial injury and the onset of new symptoms 21.9 years. The mean length of the syringes observed on preoperative magnetic resonance images was 7.8 spinal levels. Shunting procedures were performed in five patients. Four patients underwent arachnoidolysis and duraplasty. Patients developed mechanical shunt failure. Postoperatively, one patient showed clinical improvement, four patients were stable, and four patients showed deterioration.

Conclusion

PTS is a disabling sequelae of spinal cord injury, which develops months to years after spinal injury. We have to consider that patients with PTS may have poor long-term outcome.

Arachnolysis or cerebrospinal fluid diversion for adult-onset syringomyelia? A Systematic review of the literature

OBJECTIVE

To identify surgical practice patterns in the literature for nonpediatric syringomyelia by systematic review and to determine the following: 1) What is the best clinical practice of cerebrospinal fluid (CSF) diversion to maximize clinical improvement or to achieve the lowest recurrence rate? 2) Does arachnolysis, rather than CSF diversion, lead to prolonged times to clinical recurrence?

METHODS

A database search comprising PubMed, Cochrane Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, and Cochrane Database of Systematic Reviews was conducted to find pertinent articles on postinfectious, posttraumatic, or idiopathic syringomyelia.

RESULTS

An advanced PubMed search in August 2012 yielded 1350 studies, including 12 studies meeting Oxford Centre for Evidence-Based Medicine criteria for level IV evidence as a case series, with a total of 410 patients (mean age, 39 years). Data on 486 surgeries were collected. Mean follow-up data were available for 10 studies, with a mean follow-up time of 62 months. On regression analysis, increased age had a significant correlation with a higher likelihood of having clinically significant recurrence on mean follow-up (P < 0.05). The use of arachnolysis in surgery was associated with a longer duration until clinically symptomatic recurrence (P = 0.02). Data on mortality were unavailable. The mean number of surgeries per patient across all studies was 1.20 (range, 0.95-2.00).

CONCLUSIONS

With postinfectious and posttraumatic etiologies, arachnolysis was the only surgical treatment to have a statistically significant effect on decreasing recurrence rates. More prospective, randomized, controlled studies are required to reach a clear consensus.

Post-traumatic syringomyelia: outcome predictors

OBJECTIVE

To identify risk factors that predispose to post-traumatic syringomyelia (PTS) and describe the outcome of surgical management.

METHODS

Retrospective cohort study of 27 patients with post-traumatic syringomyelia. Spinal cord injury of these patients spanned the period from 1963 to 2008. All data were collected retrospectively using available medical records and radiological images.

RESULTS

There were 24 males and 3 females. The level of initial spine injury was thoracic in 21, cervical in 4, and lumbar in 2. The average age (±SD) at diagnosis of PTS was 40±13 years. The mean follow-up ±SD from injury was 18±11 years. On admission after injury, there were 14 patients with American Spinal Injuries Association (ASIA) disability scores of A, 3 with ASIA C, and 10 with ASIA score of D. At the time of diagnosis of PTS, local kyphosis at the site of injury measured 28±12°, and the residual canal was 67±19% compared to the average rostral and caudal anteroposterior diameter. Fourteen patients underwent a single operation for PTS, and 13 needed two or more procedures. In the 11 patients in whom the initial surgery included a duraplasty, 3 required reoperation for unsuccessful reduction in the size of the syrinx and failure to improve symptoms. In the 16 patients in whom the initial procedure was that of a shunt alone, 10 required revision (p=0.0718 rate of revision between shunting and duraplasty). As a result of treatment for PTS, improvement in symptoms of PTS occurred in 14, symptoms were unchanged in 10, and progressed in 3. In the 11 patients with sequential MRI scans, a significant correlation was shown between the reduction in the size of the syrinx and clinical improvement (p<0.001).

CONCLUSION

PTS is often the result of severe spinal cord injuries, with over half of patients having an ASIA disability score of A. Our review corroborates other published reports showing that PTS is associated with significant deformity and stenosis. Irrespective of treatment, over half of the patients required reoperation for their PTS. Duraplasty and arachnolysis are the preferred treatment for PTS over shunting alone. Treatment was associated with cessation of symptoms or improvement in nearly 90% of the patients.

Differential cavitation, angiogenesis and wound-healing responses in injured mouse and rat spinal cords

The vascular disruption, blood vessel loss and cavitation that occur at spinal cord injury (SCI) epicenters in mice and rats are different, but few studies have compared the acute SCI response in the two species. This is of interest since key elements of the rat SCI response are shared with humans. In this study, we investigated acute SCI responses and characterized changes in pro- and anti-angiogenic factors and matrix deposition in both species. Cavitation was absent in mouse but the area of the lesion site was 21- and 27-fold larger at 8 and 15 days post-lesion (dpl), respectively, in the rat compared to intact control. The absence of wound cavitation in the mouse was correlated with increased levels of immunoreactive pro-angiogenic, pro-matrix and pro-wound-healing factors, e.g. laminin, matrix metalloproteinase-1 (MMP-1) and vascular endothelial growth factor-A (VEGF-A) within the wound, which were 6.0-, 2.9-, and 2.8-fold, respectively, higher in the mouse compared to rats at 8 dpl. Increased axonal sparing was observed after dorsal column (DC) injury, detected by higher levels of neurofilament 200 (NF200) immunoreactivity in the dorsal column of mice compared to rats at both T7 and T9 spinal segments. Despite similar post SCI deficits in plantar heat tests at 2h after injury (1.4- and 1.6-fold lower than control mice and rats, respectively), by 7 days the magnitude of these responses were comparable to sham-treated controls in both species, while no post-SCI changes in Von Frey hair filament test response were observed in either species. We conclude that the more robust angiogenesis/wound-healing response in the mouse attenuates post-injury wound cavitation. Although the spinal cord functions that were monitored post-injury were similarly affected in both species, we suggest that the quality of the angiogenesis/wound-healing response together with the diminished lesion size seen after mouse SCI may protect against secondary axon damage and create an environment more conducive to axon sprouting/regeneration. These results suggest the potential therapeutic utility of manipulating the angiogenic response after human SCI.

Perilesional myeloradiculopathy with tethered cord in post-traumatic spinal cord injury

STUDY DESIGN

A retrospective series of cases.

OBJECTIVE

To identify, among post-traumatic myelopathies, a specific entity in which clinical and radiological features are not extensive but are strictly limited to the perilesional zone.

SETTING

The data set of the Regional Spinal Cord Injury Department of Nantes, France.

METHODS

A systematic analysis of all traumatic spinal cord injury (SCI) patients who presented with a neurological aggravation delayed from initial injury, without syringomyelia or extensive myelomalacia.

RESULTS

Twelve patients presenting with this type of complication were identified (that is, four tetraplegics and eight paraplegics). The neurological worsening consisted in weakness of the muscles close to the motor level in five patients, and in isolated at-level neuropathic pain in seven patients. A tethered cord was evidenced by the magnetic resonance imaging (MRI) results in all of the patients. Roots were involved by the tethering on the MRI results in eight cases. Surgery, with untethering and expansile duraplasty, was performed in all cases. Surgery allowed motor recovery in patients who presented with a motor loss (motor score gain range=1-7 points; median=3) and decreased pain in all pain patients (decrease on the 10-point numerical rating scale: range=1-6 points; median=4).

CONCLUSIONS

In traumatic SCI patients, a tethered cord could be responsible for clinical and radiological changes, which are strictly localised to the perilesional area. The term perilesional myeloradiculopathy is proposed for this complication, which requires cord release surgery.

Post-traumatic deformity: prevention and management

Traumatic spinal column injuries (SCI) can result in devastating deformities that often have long-term impact on the patient's quality of life. These deformities result in pain and occasionally neurological deficits. The deformities affecting adults often differ slightly from those in the pediatric population. In adults, injuries to the spinal column frequently result in a sagittal plane deformity, such as kyphosis or lordosis. However, in children, spinal cord injuries often cause coronal deformities, such as scoliosis. Patients with post-traumatic spinal column deformities may present acutely immediately after the injury, many years after the inciting event, or at any time in-between. Patients with post-traumatic spinal deformity initially complain of pain at the site of the deformity, but with time may complain of pain above or below the deformity as a result of degenerative changes. Any change or worsening of neurological status is a worrisome complaint, and often these patients require surgical intervention. Procedures such as fusions and spinal column osteotomies have shown promising results in treating patients with post-traumatic spinal deformities and have been shown to improve their quality of life.

Experimental syringohydromyelia induced by adhesive arachnoiditis in the rabbit: changes in the blood-spinal cord barrier, neuroinflammatory foci, and syrinx formation

There are many histological examinations of syringohydromyelia in the literature. However, there has been very little experimental work on blood permeability in the spinal cord vessels and ultrastructural changes. We prepared an animal model of spinal adhesive arachnoiditis by injecting kaolin into the subarachnoid space at the eighth thoracic vertebra of rabbits. The animals were evaluated 4 months later. Of the 30 rabbits given kaolin injection into the cerebrospinal fluid, 23 showed complete circumferential obstruction. In the 7 animals with partial obstruction of the subarachnoid space, intramedullary changes were not observed. However, among the 23 animals showing complete obstruction of the subarachnoid space, dilatation of the central canal (hydromyelia) occurred in 21, and intramedullary syrinx (syringomyelia) was observed in 11. In animals with complete obstruction, fluorescence microscopy revealed intramedullary edema around the central canal, extending to the posterior columns. Electron microscopy of hydromyelia revealed a marked reduction of villi on the ependymal cells, separation of the ependymal cells, and cavitation of the subependymal layer. The dilated perivascular spaces indicate alterations of fluid exchange between the subarachnoid and extracellular spaces. Syringomyelia revealed that nerve fibers and nerve cells were exposed on the surface of the syrinx, and necrotic tissue was removed by macrophages to leave a syrinx. Both pathologies differ in their mechanism of development: hydromyelia is attributed to disturbed reflux of cerebrospinal fluid, while tissue necrosis due to disturbed intramedullary blood flow is considered to be involved in formation of the syrinx in syringomyelia.

Treatment of posttraumatic syringomyelia

Object

This paper presents results of a prospective study for patients undergoing surgery for posttraumatic syringomyelia between 1991 and 2010.

Methods

A group of 137 patients with posttraumatic syringomyelia were evaluated (mean age 45 ± 13 years, mean follow-up 51 ± 51 months) with pre- and postoperative MRI and clinical examinations presenting in this period and followed prospectively by outpatient visits and questionnaires. Surgery was recommended for symptomatic patients with a progressive course. Short-term results were determined within 3 months of surgery, whereas long-term outcomes in terms of clinical recurrences were studied with Kaplan-Meier statistics.

Results

Three groups were distinguished according to the type of trauma: Group A, patients with spinal trauma but without cord injury (ASIA E, n = 37); Group B, patients with an incomplete cord injury (ASIA C or D, n = 55); and Group C, patients with complete loss of motor function or a complete cord injury (ASIA A or B, n = 45). Overall, 61 patients with progressive symptoms underwent 71 operations. Of these operations, 61 consisted of arachnolysis, untethering, and duraplasty at the trauma level (that is, decompression), while 4 ASIA A patients underwent a cordectomy. The remaining procedures consisted of placement of a thecoperitoneal shunt, 2 opiate pump placements, and 2 anterior and 1 posterior cervical decompression and fusion. Seventy-six patients were not treated surgically due to lack of neurological progression or refusal of an operation. Neurological symptoms remained stable for 10 years in 84% of the patients for whom surgery was not recommended due to lack of neurological progression. In contrast, 60% of those who declined recommended surgery had neurological progression within 5 years. For patients presenting with neurological progression, outcome was better with decompression. Postoperatively, 61% demonstrated a reduction of syrinx size. Although neurological symptoms generally remained unchanged after surgery, 47% of affected patients reported a postoperative improvement of their pain syndrome. After 3 months, 51% considered their postoperative status improved and 41% considered it unchanged. In the long-term, favorable results were obtained for Groups A and C with rates for neurological deterioration of 6% and 14% after 5 years, respectively. In Group B, this rate was considerably higher at 39%, because arachnolysis and untethering to preserve residual cord function could not be fully achieved in all patients. Cordectomy led to neurological improvement and syrinx collapse in all 4 patients.

Conclusions

The technique of decompression with arachnolysis, untethering, and duraplasty at the level of the underlying trauma provides good long-term results for patients with progressive neurological symptoms following ASIA A, B and E injuries. Treatment of patients with posttraumatic syringomyelia after spinal cord injuries with preserved motor functions (ASIA C and D) remains a major challenge. Future studies will have to establish whether thecoperitoneal shunts would be a superior alternative for this subgroup.

Spinal syringomyelia following subarachnoid hemorrhage

Subarachnoid blood has been reported as a cause of chronic spinal arachnoiditis. Although syringomyelia has been thought to be caused by spinal arachnoiditis, reports of syringomyelia following aneurysmal subarachnoid hemorrhage (SAH) are very rare. We describe two patients with syringomyelia associated with chronic spinal arachnoiditis following SAH. From January 2001 to December 2010, 198 patients with aneurysmal SAH were treated at Kinki University School of Medicine. Two of the 198 patients had syringomyelia following aneurysmal SAH; thus the rate of syringomyelia associated with aneurysmal SAH was 1.0%. Patient 1 was a 54-year-old woman who presented with back pain, back numbness and gait disturbance 20 months after SAH. Her MRI revealed syringomyelia of the spinal cord from C2 to T10. She underwent shunting of the syrinx to the subarachnoid space. Patient 2 was a 49-year-old man, who was admitted to the hospital with headache, diplopia, hoarseness, dysphagia and ataxia five months after SAH. MRI revealed syringomyelia from the medulla oblongata to C6, and an enlargement of the lateral and fourth ventricles. After foramen magnum decompression and C1 laminectomy, a fourth ventricle-subarachnoid shunt was placed by insertion of a catheter. Spinal arachnoiditis and spinal syringomyelia are rare but important chronic complications after SAH.

Focal adhesive arachnoiditis of the spinal cord: Imaging diagnosis and surgical resolution

Background:

Although adhesive arachnoiditis of the spinal cord can cause progressive symptoms associated with syringomyelia or myelomalacia, its surgical resolution based on the imaging diagnosis is not well characterized. This study aims to describe the use of imaging for the diagnosis of focal adhesive arachnoiditis of the spinal cord and its surgical resolution using microsurgical arachnoidolysis.

Materials and Methods:

Four consecutive patients with symptomatic syringomyelia or myelomalacia caused by focal adhesive arachnoiditis underwent microsurgical arachnoidolysis. Comprehensive imaging evaluation using constructive interference in steady-state (CISS) magnetic resonance imaging (MRI) or myelographic MR imaging using true fast imaging with steady-state precession (TrueFISP) sequences was included before surgery to determine the surgical indication.

Results:

In all four patients a focal adhesion was identified at the cervical or thoracic level of the spinal cord, a consequence of infection or trauma. Three patients showed modest or minor improvement in neurological function, and one patient was unchanged after surgery. The syringomyelia or myelomalacia resolved after surgery and no recurrence was noted within the follow-up period, which ranged from 5 months to 30 months.

Conclusions:

MRI diagnosis of focal adhesive arachnoiditis is critical to determine the surgical indication. Microsurgical arachnoidolysis appears to be a straightforward method for stabilizing the progressive symptoms, though the procedure is technically demanding.

The challenges of managing spine and spinal cord injuries: an evolving consensus and opportunities for change

The current Spine Focus Issue reflects the collective efforts of members of the Spine Trauma Study Group, and seeks to summarize as well as critically evaluate many of the key controversies related to the management of spinal trauma and spinal cord injury. Some of the topics discussed in this issue include the optimal timing for surgical intervention in spinal cord injury and central cord syndrome, the optimal treatment for both elderly and skeletally mature individuals with odontoid process fractures, management of pediatric spine trauma, rehabilitation strategies for the spinal injured patient, return to play guidelines, and variations in international practice patterns for the management of common spine trauma scenarios. The current Spine issue serves as an update to clinicians on these topics as well as a framework for stimulating new discussion and research in the field as a whole.

Surgical management of post-traumatic syringomyelia

STUDY DESIGN

Systematic review.

OBJECTIVE

To determine the indications for surgical intervention and optimal surgical treatment technique for patients with post-traumatic syringomyelia and spinal cord tethering.

SUMMARY OF BACKGROUND DATA

The proper management strategy for post-traumatic syringomyelia has not been established. Most modern surgical series have documented improvement in symptomatic patients who have an internal decompression of their syrinx. Several options exist and include shunting the syrinx (to the subarachnoid space or to either the pleural or peritoneal cavities) as well as spinal cord untethering (with or without expansile duraplasty).

METHODS

A systematic review of literature followed by expert panel consensus was performed. English language literature published between 1980 and 2010 was gathered to examine articles search was conducted using the search terms syringomyelia, syrinx, spinal cord injury, traumatic syringomyelia, post-traumatic syringomyelia. Case reports and articles examining syrinx due to other cause were excluded. Articles were graded for strength of evidence according to the GRADE approach. The evidentiary tables were reviewed and approved by all 4 authors, and disagreements were resolved by consensus.

RESULTS

The literature search yielded a total of 296 abstracts, and 22 articles were found to fulfill all the criteria specified above. All identified articles were of low or very low evidence levels. The reported incidence of post-traumatic syringomyelia is 0.5% to 4.5%; the incidence is twice as common in complete versus incomplete injuries. The literature consistently demonstrated that surgery post-traumatic syringomyelia is effective at arresting or improving motor deterioration, but not sensory dysfunction or pain syndromes. The literature does not support surgical intervention for incidental, asymptomatic syrinx. The literature does not support one surgical technique as superior for the treatment of post-traumatic syringomyelia.

CONCLUSION

The literature supports and the consensus panel recommended that there is no indication for direct decompression at the time of initial injury specifically for the purpose of limiting future risk of syringomyelia. The literature supports and the consensus panel gave a strong recommendation for surgical intervention in the setting of motor neurologic deterioration as a consequence of post-traumatic syrinx/tethered cord. The panel gave a weak recommendation against surgical intervention for patients developing sensory loss/pain syndrome or for asymptomatic but expanding syrinx. Finally, the literature does not provide strong evidence to support the superiority of one surgical technique over the others; however, the consensus panel gave a weak recommendation that spinal cord untethering with expansile duraplasty is the preferred first-line surgical technique.

Surgical Treatment of Posttraumatic Syringomyelia

OBJECTIVE

The present study evaluates the effectiveness of 2 surgical procedures, shunting and untethering, for posttraumatic syringomyelia.

METHODS

We retrospectively reviewed the medical charts of all surgical patients with posttraumatic syringomyelia in our department. Shunting was performed before 1997; after 1997, we used arachnoidolysis and untethering.

RESULTS

Shunting was performed in 15 patients, and 19 patients underwent arachnoidolysis. Statistical analysis found that the 2 groups did not differ in age or initial clinical or radiological presentation. All patients suffered from progressively worsening symptoms. Reconstruction of the subarachnoid space by arachnoidolysis and untethering the cord allowed us to improve or stabilize 94% of our patients. Shunting exposed the patients to a higher rate of clinical recurrence and reoperation. Comparisons between the 2 groups found a significant difference (better results) in favor of arachnoidolysis for the McCormick classification (P = .03), American Spinal Injury Association motor score of the lower extremities (P = .02), and subjective grading (P = .001). There was no significant difference in the evolution of pain or the Vaquero index between the 2 groups; however, a tendency appeared in favor of arachnoidolysis for cyst evolution in regard to the extent of the cyst and the Vaquero index (P = .05).

CONCLUSION

Our results confirmed that arachnoidolysis is an effective and safe treatment for posttraumatic syringomyelia. Because the majority of patients were stabilized, we concluded that surgery should be performed as soon as possible in patients with clearly progressing clinical features.

Role of the blood-spinal cord barrier in posttraumatic syringomyelia

OBJECT

Posttraumatic syringomyelia produces a significant burden of pain and neurological deficits in patients with spinal cord injury. The mechanism of syrinx formation is unknown and treatment is often ineffective. A possible explanation for syrinx formation is fluid leakage from the microcirculation in the presence of a compromised blood-spinal cord barrier (BSCB). The aim of this study was to investigate the structural and functional integrity of the BSCB in a model of posttraumatic syringomyelia.

METHODS

The excitotoxic amino acid and arachnoiditis model of syringomyelia was used in 27 Sprague-Dawley rats. Structural integrity of the BSCB was assessed using immunoreactivity to endothelial barrier antigen (EBA), and loss of functional integrity was assessed by extravasation of intravascular horseradish peroxidase. Animals were studied after 3 days, or at 1, 3, 6, or 12 weeks after surgery. There were laminectomy-only and saline injection control animals for comparison at each time point.

RESULTS

Syrinxes formed in 16 of the 17 animals injected with excitotoxic amino acid. Loss of structural and functional integrity of the BSCB in syrinx animals was noted at all time points. Disruption of the BSCB was most dramatic in tissue adjacent to the syrinx, and in the central and dorsal gray matter. Changes in EBA expression generally corresponded with altered vascular permeability, although in the acute stages, widespread vascular permeability occurred without a corresponding decrease in EBA expression. At the later time points (3-12 weeks) EBA expression was often absent, although no vascular leakage was observed.

CONCLUSIONS

This study demonstrated a prolonged structural and functional disruption of the BSCB in this model of posttraumatic syringomyelia. Loss of functional integrity of the BSCB, with fluid entering the interstitial space of the spinal cord, may contribute to initial cyst formation after spinal cord injury and subsequent enlargement of the cyst, to produce posttraumatic syringomyelia.

The influence of coughing on cerebrospinal fluid pressure in an in vitro syringomyelia model with spinal subarachnoid space stenosis

Background

The influence of coughing, on the biomechanical environment in the spinal subarachnoid space (SAS) in the presence of a cerebrospinal fluid flow stenosis, is thought to be an important etiological factor in craniospinal disorders, including syringomyelia (SM), Chiari I malformation, and hydrocephalus. The aim of this study was to investigate SAS and syrinx pressures during simulated coughing using in vitro models and to provide information for the understanding of the craniospinal fluid system dynamics to help develop better computational models.

Methods

Four in vitro models were constructed to be simplified representations of: 1) non-communicating SM with spinal SAS stenosis; 2) non-communicating SM due to spinal SAS stenosis with a distensible spinal column; 3) non-communicating SM post surgical removal of a spinal SAS stenosis; and 4) a spinal SAS stenosis due to spinal trauma. All of the models had a flexible spinal cord. To simulate coughing conditions, an abrupt CSF pressure pulse (~ 5 ms) was imposed at the caudal end of the spinal SAS by a computer-controlled pump. Pressure measurements were obtained at 4 cm intervals along the spinal SAS and syrinx using catheter tip transducers.

Results

Pressure measurements during a simulated cough, showed that removal of the stenosis was a key factor in reducing pressure gradients in the spinal SAS. The presence of a stenosis resulted in a caudocranial pressure drop in the SAS, whereas pressure within the syrinx cavity varied little caudocranially. A stenosis in the SAS caused the syrinx to balloon outward at the rostral end and be compressed at the caudal end. A >90% SAS stenosis did not result in a significant Venturi effect. Increasing compliance of the spinal column reduced forces acting on the spinal cord. The presence of a syrinx in the cord when there was a stenosis in the SAS, reduced pressure forces in the SAS. Longitudinal pressure dissociation acted to suck fluid and tissue caudocranially in the SAS with a stenosis.

Conclusions

Pressures in the spinal SAS during a simulated cough in vitro had similar peak, transmural, and longitudinal pressures to in vivo measurements reported in the literature. The pressure wave velocities and pressure gradients during coughing (longitudinal pressure dissociation and transmural pressure) were impacted by alterations in geometry, compliance, and the presence of a syrinx and/or stenosis.

Posttraumatic spinal cord tethering and syringomyelia: surgical treatment and long-term outcome

Object

Permanent neurological loss after spinal cord injury (SCI) is a well-known phenomenon. There has also been a growing recognition and improved understanding of the pathophysiological mechanisms of late progressive neurological loss, which may occur after SCI as a result of posttraumatic spinal cord tethering (SCT), myelomalacia, and syringomyelia. A clinical study of 404 patients sustaining traumatic SCIs and undergoing surgery to arrest a progressive myelopathy caused by SCT, with or without progressive myelomalacia and cystic cavitation (syringomyelia) was undertaken. Both objective and subjective long-term outcomes were evaluated. To the authors' knowledge, this is the first series of this size correlating long-term patient perception of outcome with long-term objective outcome analyses.

Methods

During the period from January 1993 to November 2003, 404 patients who had previously sustained traumatic SCIs underwent 468 surgeries for progressive myelopathies attributed to tethering of the spinal cord to the surrounding spinal canal, with or without myelomalacia and syrinx formation. Forty-two patients were excluded because of additional pathological entities that were known to contribute to a progressive myelopathy. All surgeries were performed by the same neurosurgeon at a single SCI treatment center and by using a consistent surgical technique of spinal cord detethering, expansion duraplasty, and when indicated, cyst shunting.

Results

Outcome data were collected up to 12 years postoperatively. Comparisons of pre- and postoperative American Spinal Injury Association sensory and motor index scores showed no significant change when only a single surgery was required (86% of patients). An outcome questionnaire and phone interview resulted in > 90% of patients self-assessing arrest of functional loss; > 50% of patients self-assessing improvement of function; 17 and 18% self-assessing improvement of motor and sensory functions to a point greater than that achieved at any time postinjury, respectively; 59% reporting improvement of spasticity; and 77% reporting improvement of hyperhidrosis.

Conclusions

Surgery for spinal cord detethering, expansion duraplasty, and when indicated, cyst shunting, is a successful treatment strategy for arresting a progressive myelopathy related to posttraumatic SCT and syringomyelia. Results suggest that surgery leads to functional return in ~ 50% of patients, and that in some patients posttraumatic SCT limits maximal recovery of spinal cord function postinjury. A patient's perception of surgery's failure to arrest the progressive myelopathy corresponds closely with the need for repeat surgery because of retethering, cyst reexpansion, and pseudomeningocele formation.

Surgical management of posttraumatic thoracolumbar kyphosis

BACKGROUND CONTEXT

Spine trauma is relatively common, and each year approximately 10,000 to 17,000 people in the United States will sustain a spinal cord injury and approximately 150,000 to 160,000 will fracture their spinal column. Posttraumatic spinal deformity is a common potential complication of spinal injury and poses one of the greatest challenges in spinal surgery.

PURPOSE

To provide a comprehensive and current review of posttraumatic deformity focusing on the epidemiology, clinical and radiographical presentation, treatment options, and prognosis.

STUDY DESIGN/SETTING

A thorough review of the English literature on the management of posttraumatic deformity was performed. Pertinent articles were identified by using PubMed and a review of publications by the American Academy of Orthopaedic Surgeons.

METHODS

Each article was reviewed, and findings were analyzed to formulate a concise review of current treatment methods for posttraumatic deformity.

RESULTS

Successful treatment of posttraumatic deformity is dependent on careful patient selection and appropriate surgical intervention, which should be considered in the presence of significant or increasing deformity, increasing back and/or leg pain, "breakdown" at levels above or below the deformity, pseudarthrosis or malunion, and increasing neurological deficit. The goals of surgery should be to decompress the neural elements if neurological claudication or a neurological deficit is present, to recreate normal sagittal contours and balance, and to optimize the chances for successful fusion; these goals can be achieved through an all-anterior, all-posterior, or a combined anterior/posterior approach assuming that close attention is paid to using the appropriate bone-grafting techniques, selecting technically sound segmental instrumentation, and providing appropriate biomechanical environment for maintenance of correction and successful fusion.

CONCLUSIONS

Posttraumatic spinal deformity is a common complication of spinal injury, and it is therefore essential for patients with vertebral column injuries to have a careful initial evaluation, close follow-up, and early intervention when needed. Once posttraumatic deformity is present, successful outcome is achievable assuming a thorough, systematic, and technically well-executed surgical intervention is performed.

Post-traumatic syringomyelia producing paraplegia in an infant

BACKGROUND

Post-traumatic syringomyelia is described in adults after spinal trauma but extremely rarely seen in children, especially in the first year of life.

MATERIALS AND METHODS

We describe a boy who, at the age of 7 months, suffered spinal trauma during a car accident when he was held at his mother's lap and suffered extreme flexion of his torso. He suffered a mid-shaft fracture of his right femur, treated with hip spica for 6 weeks. After removal of the spica, it was noticed that he was not moving his legs, but he had preserved pain sensation in the lower half of his trunk and legs. A spine magnetic resonance scan performed 2 months after the injury showed a compressed wedge fracture of the body of T5 vertebra, kyphosis and a large syringomyelia cavity extending from T4 to T8. He had two operations to control the syringomyelia with laminotomy-laminoplasty, dissection of the arachnoid adhesions initially and drainage of the cavity on the second operation, with only modest success. He remains paraplegic 7 years after the injury. He has received thoracic brace immediately after the first spinal operation, which avoided kyphosis.

DISCUSSION

Spinal trauma is rare in the first year of life; hence, post-traumatic syringomyelia is very rarely seen in infants. Nevertheless, it should be suspected after a major trauma, in the presence of paraplegia. Surgical treatment of post-traumatic syringomyelia in young children has the additional consideration of post-laminotomy kyphosis; hence, thoracic brace should be used early.

The role of spinal tissue scarring in the pathogenesis of progressive post-traumatic myelomalacia

OBJECTIVES

Experimental spinal cord injury (SCI) with focal spinal tissue scarring was studied to better understand the progressive post-traumatic myelomalacia (PPM).

METHODS

Using a stereotactic device, the authors developed an acute compression of spinal cord at Th-10 in the adult rat. In Group A, the rat thoracic spinal cord was compressed epidurally with preservation of local cerebrospinal fluid (CSF) dynamics. In Group B (spinal tissue scarring), the rat thoracic spinal cord was compressed directly after disruption of meninges of dura mater and arachnoid membrane, followed by gelatine sponge sealing. All rats were maintained for 12 weeks after injury.

RESULTS

Imaging analysis revealed the significant increase of cystic cavitation in the contused spinal cord in Group B compared with Group A. Anterograde axonal tracing demonstrated that the labeled corticospinal axons had extended axonal sprouting into the nearby gray matter and displayed prominent dieback at the rostral interface of the spinal cord lesion in both groups. No significant difference in motor and sensory functions between the two groups was noted.

DISCUSSION

The new experimental model of PPM formation was devised. Spinal tissue scarring at the injury site may cause a tethering effect on the spinal cord, which may lead to significant alteration of the spinal cord parenchyma. Although the devastating effect of PPM on motor and sensory functions is still not resolved completely, the results in the present study suggest the importance of careful analysis in the treatment of PPM after SCI.

Unraveling the riddle of syringomyelia

The pathophysiology of syringomyelia development is not fully understood. Current prevailing theories suggest that increased pulse pressure in the subarachnoid space forces cerebrospinal fluid (CSF) through the spinal cord into the syrinx. It is generally accepted that the syrinx consists of CSF. The here-proposed intramedullary pulse pressure theory instead suggests that syringomyelia is caused by increased pulse pressure in the spinal cord and that the syrinx consists of extracellular fluid. A new principle is introduced implying that the distending force in the production of syringomyelia is a relative increase in pulse pressure in the spinal cord compared to that in the nearby subarachnoid space. The formation of a syrinx then occurs by the accumulation of extracellular fluid in the distended cord. A previously unrecognized mechanism for syrinx formation, the Bernoulli theorem, is also described. The Bernoulli theorem or the Venturi effect states that the regional increase in fluid velocity in a narrowed flow channel decreases fluid pressure. In Chiari I malformations, the systolic CSF pulse pressure and downward motion of the cerebellar tonsils are significantly increased. This leads to increased spinal CSF velocities and, as a consequence of the Bernoulli theorem, decreased fluid pressure in narrow regions of the spinal CSF pathways. The resulting relatively low CSF pressure in the narrowed CSF pathway causes a suction effect on the spinal cord that distends the cord during each systole. Syringomyelia develops by the accumulation of extracellular fluid in the distended cord. In posttraumatic syringomyelia, the downwards directed systolic CSF pulse pressure is transmitted and reflected into the spinal cord below and above the traumatic subarachnoid blockage, respectively. The ensuing increase in intramedullary pulse pressure distends the spinal cord and causes syringomyelia on both sides of the blockage. The here-proposed concept has the potential to unravel the riddle of syringomyelia and affords explanations to previously unanswered clinical and theoretical problems with syringomyelia. It also explains why syringomyelia associated with Chiari I malformations may develop in any part of the spinal cord including the medullary conus. Syringomyelia thus preferentially develops where the systolic CSF flow causes a suction effect on the spinal cord, i.e., at or immediately caudal to physiological or pathological encroachments of the spinal subarachnoid space.

Post-traumatic syringomyelia: a review of the cases presenting in a regional spinal injuries unit in the north east of England over a 5-year period

STUDY DESIGN

Retrospective study of the management of patients with a confirmed diagnosis of post-traumatic syringomyelia (PTS) in a regional spinal injuries unit.

OBJECTIVES

To investigate the incidence of PTS in a regional spinal injuries unit, and to assess mode of presentation, management, and subsequent outcome.

SUMMARY OF BACKGROUND DATA

Majority of patients male, mean age 44 years (range 33-60 years), with thoracic spinal cord injury (SCI). Most PTS developed within 5 years after injury (range 6 months to 25 years) and presented with reduced sensation. Fifty percent had surgical intervention at the time of SCI, and 50% managed conservatively. Four patients had additional spinal injury pathology not corrected at time of surgery.

METHODS

Retrospective analysis of the case notes of all patients with a confirmed diagnosis of PTS (n = 16). Demographic details obtained and details of the original injury and subsequent clinical course and management noted.

RESULTS

Incidence of PTS = 0.02%. Magnetic resonance imaging scanning performed in 56% with PTS. The majority of PTS developed around the site of the original lesion. The most common method of management was insertion of a syringoperitoneal shunt (44%). Thirty-one percent improved after surgery, 31% remain stable. One patient died. The symptoms of 3 patients continue to deteriorate slowly despite surgical intervention.

CONCLUSIONS

Incidence of PTS are lower in our study than that quoted in the literature. Benefits of initial surgical management of SCI in reducing development of PTS are unclear. Benefits of surgical management of PTS are unclear. Additional studies are required as this may influence future management of spinal cord injured patients.

The pathogenesis of syringomyelia associated with lesions at the foramen magnum: a critical review of existing theories and proposal of a new hypothesis

Syringomyelia is frequently accompanied by an extramedullary lesion at the foramen magnum, particularly a Chiari I malformation. Although syringomyelia associated with foramen magnum obstruction has characteristic clinical, radiological, and neuropathological features, its pathogenesis remains unclear. Currently prevalent hydrodynamical theories assert that obstruction of the subarachnoid space at the foramen magnum interferes with flow of cerebrospinal fluid (CSF) between the spinal and the intracranial subarachnoid compartments. As a result, spinal CSF is driven into the spinal cord through the perivascular spaces to form a syrinx. These theories are implausible biophysically because none postulates a pump adequate to drive fluid through these spaces. None of the theories can explain why syrinx pressure is higher than CSF pressure; why extensive gliosis, edema, and vascular wall thickening regularly occur; and why the composition of syrinx fluid is not identical with that of CSF. A new theory of pathogenesis is proposed to address these difficulties. In the presence of subarachnoid obstruction at the foramen magnum, a variety of activities, such as assuming the erect posture, coughing or straining, and pulsatile fluctuations of CSF pressure during the cardiac cycle, produce transiently higher CSF pressure above the block than below it. There are corresponding changes in transmural venous and capillary pressure favoring dilation of vessels below the block and collapse of vessels above the block. The spatially uneven change of vessel caliber produces mechanical stress on the spinal cord, particularly caudal to the block. The mechanical stress, coupled with venous and capillary dilation, partially disrupt the blood-spinal cord barrier, allowing ultrafiltration of crystalloids and accumulation of a protein-poor fluid. The proposed theory is consistent with the neuropathological findings in syringomyelia and with the pressure and composition of syrinx fluid. It also accounts for the prolonged course of syringomyelia and its aggravation by cough, strain, and assumption of an erect posture. It contributes to understanding the low incidence and the morphology of syringobulbia. It explains the poorly understood presentation of foramen magnum meningiomas with symptoms of a mid- to low-cervical myelopathy. The theory also affords an understanding of the late recurrence of symptoms in children with hydromyelia who are treated with a ventricular shunt.

The role of excitotoxic injury in post-traumatic syringomyelia

Fifty percent of patients with neurological deterioration from post-traumatic syringomyelia do not respond to treatment. Treatment failure is due in part to an incomplete understanding of the underlying aetiology. An animal model that mimics the human disease is required to investigate underlying pathophysiology and treatment options. A previous study was designed to mimic trauma-induced effects on the spinal cord that result in syringomyelia, combining an excitotoxic insult with kaolin-induced arachnoiditis. In this excitotoxic model, syringes were produced in 82% of animals. The aims of the current study were to improve the model to produce syringes in all animals treated, to examine the relative influences of excitotoxic injury and neuronal loss on syrinx formation, and to use magnetic resonance imaging (MRI) to examine syringes non-invasively. A temporal and dose profile of intraparenchymal quisqualic acid (QA) and subarachnoid kaolin was performed in Sprague Dawley rats. MRI was used to study four syrinx and six control animals. In one subgroup of animals surviving for 6 weeks, 100% (eight of eight) developed syringes. Syrinx formation and enlargement occurred in a dose and time dependent manner, whilst significant neuronal loss was only dose dependent. Animal syrinx histology closely resembled human post-traumatic syringomyelia. Axial T2-weighted MR images demonstrated syrinx presence. The results suggest that the formation of an initial cyst predisposes to syrinx formation in the presence of subarachnoid adhesions.

Altered subarachnoid space compliance and fluid flow in an animal model of posttraumatic syringomyelia

STUDY DESIGN

A histologic study of cerebrospinal fluid tracers in Sprague-Dawley rats undergoing lumboperitoneal shunt insertion in the excitotoxic animal model of posttraumatic syringomyelia (PTS).

OBJECTIVES

To determine the effects of cerebrospinal fluid (CSF) diversion from the subarachnoid space on perivascular flow (PVS) and syrinx formation in posttraumatic syringomyelia.

SUMMARY OF BACKGROUND DATA

In an animal model of PTS, fluid enters syringes from the subarachnoid space via perivascular spaces. Preferential PVS flow occurs at the level of the syrinx. It has been suggested that arachnoiditis predisposes to posttraumatic syringomyelia formation by obstructing subarachnoid cerebrospinal fluid flow and enhancing perivascular flow.

MATERIALS AND METHODS

Thirty-two male Sprague-Dawley rats were investigated using the CSF tracer horseradish peroxidase (HRP), the excitotoxic model of PTS, and lumboperitoneal shunt insertion. Five experimental groups consisted of normal controls, syrinx only and shunt only controls, and shunt insertion before or after syrinx formation. In all groups except normal controls, CSF flow studies were performed 6 weeks after the final intervention. Grading scales were used to quantify HRP staining.

RESULTS

All excitotoxic model animals formed syringes. Perivascular flow was greatest at the level of the syrinx. Cerebral cortex perivascular flow was significantly reduced after shunt insertion in animals with a syrinx (P < 0.05). Shunt insertion did not alter syrinx length or size. There were no significant differences between shunt and syrinx first groups.

CONCLUSIONS

Increasing caudal subarachnoid space compliance with a shunt does not affect local CSF flow into the spinal cord and syrinx. These results suggest that localized alterations in compliance, as opposed to obstruction from traumatic arachnoiditis, may act as an important factor in syrinx pathogenesis.

Critical care and perioperative management in traumatic spinal cord injury

Traumatic spinal cord injury is frequently associated with brain injury and with alterations in respiratory and cardiovascular function that require critical care management. Complications include respiratory failure, atelectasis, pneumonia, neurogenic shock, autonomic dysreflexia, venous thromboembolism, and sepsis. While complications may be managed with supportive care, the goal of ameliorating neurologic outcome has proved elusive. Methylprednisolone, when instituted <8 hours after traumatic spinal cord injury, was associated in two clinical trials with statistically significant improvements in motor scores at 6 months and 1 year; however, critical reappraisal of these data raises questions about their validity and clinical relevance. Until more evidence of clinically effective therapies is available, acute management must be driven by pathophysiologic principles, with emphasis on interventions that attenuate secondary neurologic injury; these include the rational use of immobilization, cautious airway management, and promotion of cord perfusion and oxygenation with the appropriate level of hemodynamic and respiratory support. Clinical trials of pharmacologic neuroprotection have yielded disappointing results, but the ongoing elucidation of spinal cord repair and regenerative mechanisms suggests new therapeutic prospects.