A case of idiopathic spinal cord herniation with duplicated dura mater

Unveiling the Current Understanding of Idiopathic Spinal Cord Herniation: A Systematic Review

Background

Idiopathic spinal cord herniation (ISCH) is a rare condition that is characterized by ventral herniation of the spinal cord through a defect in the dura mater into the epidural space, with no identifiable cause. ISCH is frequently underdiagnosed, and the information available in case reports is limited. To provide an overview of the clinical manifestations and diagnosis of this condition, this study aims to conduct a review of reported cases of ISCH.

Methods

A literature review was carried out using seven databases. The search was conducted using the keywords "Idiopathic spinal cord herniation" OR "Idiopathic Ventral Spinal Cord Herniation" AND "Case report" OR "case series."

Results

A total of 92 relevant papers reporting 224 cases, besides the index case, were determined. Of the cases, 58.5% were females and the mean age was 50.7 (SD 13.2) years. Symptoms, diagnoses, and outcomes were similar between genders. The most common clinical signs included motor symptoms (82.6%), instability (61.3%), hypoesthesia (59.2%), and disturbance of thermal sensitivity (47.3%). Brown-Séquard syndrome was observed in 27.2% of the cases, and surgical treatment was employed in 89.7% of the cases.

Conclusions

ISCH is a pathology that is principally treated with surgical approach. This study provides valuable insights into the clinical manifestations and diagnosis of ISCH, which can aid in the early recognition and treatment of this rare condition.

Idiopathic Ventral Spinal Cord Hernia-A Single-Center Case Series of 11 Patients

BACKGROUND

Idiopathic spinal cord herniations (ISCH) are rare defects of the ventromedial or mediolateral dura mater with herniation of the spinal cord through the defect with approximately 350 described cases worldwide. Patients usually become symptomatic with motor or sensory neurological deficits and gait disturbances.

OBJECTIVE

To describe characteristic symptoms and clinical findings and to evaluate the postoperative course and outcomes of ISCH.

METHODS

We present a single-center data analysis of a case series of 11 consecutive patients who were diagnosed with ISCH and underwent surgery in our department between 2009 and 2021.

RESULTS

All herniations were located in the thoracic spine between T2 and T9. In most cases, gait ataxia and dysesthesia led to further workup and subsequently to the diagnosis of ISCH. A "far-enough" posterior-lateral surgical approach, hemilaminectomy or laminectomy with a transdural approach, was performed under intraoperative neurophysiological monitoring which was followed by adhesiolysis, repositioning of the spinal cord and sealing using a dura patch. After surgery, clinical symptoms improved in 9 of 11 patients (81.8%), while only 1 patient experienced deterioration of symptoms (9.1%) and 1 patient remained equal (9.1%). The median preoperative McCormick grade was 3 (±0.70), while the median postoperative grade was 2 (±0.98) ( P = .0047).

CONCLUSION

In our case series of ISCH, we found that in most patients, neurological deficits improved postoperatively. This indicates that surgery in ISCH should not be delayed in symptomatic patients.

Idiopathic herniation of the thoracic spinal cord

Since 1974, when Wortzman et al were the first to describe a case of idiopathic spinal cord herniation (ISCH), the number of reported cases has increased owing to magnetic resonance imaging (MRI) now is routinely available for patients with myelopathy and spinal surgeons are becoming more familiar with this clinical entity. This extremely rare herniation occurs exclusively in the thoracic spine, causing slowly progressive myelopathy. Diagnosis is based on ventral displacement of the spinal cord in the thoracic spine. MRI is the technique of choice to exclude a posterior arachnoid cyst, the most common mistaken diagnosis, and to recognize a spinal cord herniation when an anterior dural defect is present. A case of ISCH is reported and a Literature review of this clinical entity often mis-diagnosed has been obtained.

Novel Strategy of Ventral Dural Repair for Idiopathic Thoracic Spinal Cord Herniation: Report of Outcomes and Review of Techniques

BACKGROUND

Idiopathic ventral thoracic spinal cord herniation is a rare condition that usually presents with progressive myelopathy or Brown-Séquard syndrome. More than 100 cases have been reported with significant variance in surgical treatment strategies and likewise, significant variance in patient outcomes. Although laminectomy has often been used, to date, there is no consensus regarding the optimal surgical approach or strategy for ventral dural repair.

OBJECTIVE

To report and illustrate a novel approach to repair the ventral dural defect with more than 2 yr of clinical follow-up. The specific approach and graft used are both detailed.

METHODS

A retrospective chart review of all known cases of idiopathic spinal cord herniation at the Cleveland Clinic over the last 15 yr was performed. Postoperative outcome scores (including the Japanese Orthopedic Association score, European Myelopathy score, and Nurick) were calculated preoperatively and postoperatively.

RESULTS

A total of 5 patients were identified. Four of five patients improved clinically after surgery and 1 patient remained unchanged at last follow-up (average 23.2 mo, range 12-60 mo). There were no complications. All patients had postoperative magnetic resonance imaging demonstrating realignment of the spinal cord and no recurrence of tethering.

CONCLUSION

A unilateral dorsolateral, transpedicular approach combined with laminectomy provides excellent exposure for ventral or ventrolateral dural defects associated with idiopathic spinal cord herniation and minimizes spinal cord manipulation. A collagen matrix graft used as an onlay between the spinal cord and ventral dural defect is a safe and effective option for ventral dural repair.

Idiopathic Spinal Cord Herniation Associated With a Thoracic Disc Herniation: Case Report, Surgical Video, and Literature Review

PURPOSE

The aim of this publication is to present a case of idiopathic spinal cord herniation (ISCH) associated with a transdural disk herniation, demonstrate an operative technique used to treat this condition and provide an updated review the literature.

BACKGROUND CONTEXT

ISCH is an infrequent condition that can cause progressive myelopathy leading to severe neurological dysfunction. This condition is characterized by ventral displacement of the spinal cord across a defect in the dura, either congenital or acquired, resulting in vascular compromise and adhesion that subsequently causes injury to the spinal cord. We present the management of such a patient, in addition to a review of the literature regarding management of ISCH.

METHODS

This patient underwent surgery using the dural graft sling technique for repair of the dural defect and restoration of normal spinal cord position within the thecal sac. A review of the literature revealed a total of 171 patients supplemented by our 1 patient, which were then analyzed.

RESULTS

The majority of patients, treated with a variety of surgical techniques, experienced improvements in symptomatology. Our patient experienced significant improvement in symptomatology.

CONCLUSIONS

Although ISCH is a rare clinical condition that causes myelopathy, patients managed with surgery generally, though not universally, have a favorable neurological outcome. The associated surgical technique video demonstrates the dural sling technique for the treatment of this rare disorder.

Understanding Idiopathic Spinal Cord Herniation - A Comprehensive Review of Imaging and Literature

Idiopathic spinal cord herniation (ISCH) is displacement of spinal cord through a dural or arachnoidal defect. Most patients present with back pain or myelopathy, paresthesia, and sensory or motor weakness. Imaging findings include anterior displacement of the cord with possible kink, no filling defect on CT myelography, and no restricted diffusion/mass lesion on magnetic resonance imaging. Abrupt kink in the spinal cord or widened cerebrospinal fluid (CSF) space can be caused by a variety of reasons. The differential considerations include arachnoid web, intradural extramedullary epidermoid or arachnoid cyst, abscess or cystic schwannoma. We discuss the features, imaging, differentials, and treatment of ISCH as a rare cause of such kink in the cord. While reading such cases, a radiologist should include the location, segments involved, cord signal abnormality, visible defect, scalpel sign or C–sign, ventral cord kink, nuclear trail sign, the ventral CSF space preservation, or obliteration and the type.

Duplication of Ventral Dura as a Cause of Ventral Herniation of Spinal Cord-A Report of Two Cases and Review of the Literature

BACKGROUND

Idiopathic spinal cord herniation (ISCH) is a treatable spinal disease. It is rare and often misdiagnosed, causing a delay in management. The etiology is multifactorial, with one of the causes being duplication of the ventral dura. The spinal cord herniates within this defect and becomes strangulated, causing neurological deficits. We report the duplication of a ventral spinal cord as an important cause of ISCH in our review.

CASE DESCRIPTION

We present 2 cases of ISCH with duplication of the dura, including their relevant clinical and imaging features. The patients underwent surgical reduction of the herniated spinal cord with enlargement of the defect and placement of a dural substitute ventral to the cord. We have also reported the outcomes of the 2 patients, with an emphasis on the factors predictive of poor outcomes (i.e., long-standing symptoms, a delay in intervention, poor neurological status at presentation, and a thinned out atrophic spinal cord found during surgery). We also reviewed the available data for duplication of the dura with ISCH.

CONCLUSIONS

Very few asymptomatic patients can be treated conservatively. The surgical outcomes have been favorable for symptomatic patients. Proper exposure, gentle manipulation while reducing the herniated spinal cord, enlargement of the defect, and the use of intraoperative monitoring will help limit the postoperative deficits. Duplication of the ventral dura is an important cause of ISCH. It prevents the formation of an anterior pseudomeningocele after surgery. Owing to the rarity of the disease and the lack of follow-up data with recurrence rates, it has not been possible to form clear guidelines for management.

The Pathogenesis of Ventral Idiopathic Herniation of the Spinal Cord: A Hypothesis Based on the Review of the Literature

Idiopathic ventral herniation of the spinal cord (SC) is not often encountered in daily practice. Its clinical prevalence, however, will increase through increasing awareness and more frequent use of MRI. A clear explanation of its pathophysiology has never been formulated. It was hypothesized that the findings during surgery might indicate the real causative mechanism. An extensive literature search was performed, using Embase, PubMed, and Google Scholar. Titles and abstracts were screened by two investigators, using strict inclusion and exclusion criteria. Reference lists of the full paper versions of each included article were checked. The following data were registered for the articles included: age, gender, level of herniation, relation to intervertebral disk, duration of symptoms, findings from surgery, and outcomes. Nine cases treated at our department were added. A total of 117 articles reporting on 259 patients were included. Including our cases, 268 patients were reviewed. Females outnumbered males (160/100). The mean age was 51.3 ± 12.0 years. In 236 patients, the duration of symptoms was reported: 55.5 ± 55.6 months. In 178 patients, the intraoperative findings for the herniated part of the SC were not mentioned. In 59 patients, a tumor-like extrusion was seen, without any alteration to the SC. Deformation of the SC itself was never observed. Biopsies of these structures were without clinical consequence. Based on the intraoperative findings reported in literature and the cases presented, acquired causes, such as trauma and erosion of the dura due to a herniated disk, were not plausible. We hypothesize that a non-functioning appendix to the SC can only develop during an early embryologic phase, in which several layers separate. We propose renaming this entity as congenital transdural appendix of the SC.

Differentiation of idiopathic spinal cord herniation from dorsal arachnoid webs on MRI and CT myelography

OBJECTIVE

Dorsal arachnoid webs (DAWs) and spinal cord herniation (SCH) are uncommon abnormalities affecting the thoracic spinal cord that can result in syringomyelia and significant neurological morbidity if left untreated. Differentiating these 2 entities on the basis of clinical presentation and radiological findings remains challenging but is of vital importance in planning a surgical approach. The authors examined the differences between DAWs and idiopathic SCH on MRI and CT myelography to improve diagnostic confidence prior to surgery.

METHODS

Review of the picture archiving and communication system (PACS) database between 2005 and 2015 identified 6 patients with DAW and 5 with SCH. Clinical data including demographic information, presenting symptoms and neurological signs, and surgical reports were collected from the electronic medical records. Ten of the 11 patients underwent MRI. CT myelography was performed in 3 patients with DAW and in 1 patient with SCH. Imaging studies were analyzed by 2 board-certified neuroradiologists for the following features: 1) location of the deformity; 2) presence or absence of cord signal abnormality or syringomyelia; 3) visible arachnoid web; 4) presence of a dural defect; 5) nature of dorsal cord indentation (abrupt “scalpel sign” vs “C”-shaped); 6) focal ventral cord kink; 7) presence of the nuclear trail sign (endplate irregularity, sclerosis, and/or disc-space calcification that could suggest a migratory path of a herniated disc); and 8) visualization of a complete plane of CSF ventral to the deformity.

RESULTS

The scalpel sign was positive in all patients with DAW. The dorsal indentation was C-shaped in 5 of 6 patients with SCH. The ventral subarachnoid space was preserved in all patients with DAW and interrupted in cases of SCH. In no patient was a web or a dural defect identified.

CONCLUSIONS

DAW and SCH can be reliably distinguished on imaging by scrutinizing the nature of the dorsal indentation and the integrity of the ventral subarachnoid space at the level of the cord deformity.

The Lumbosacral Dural Venous Sinus: A New Discovery with Potential Clinical Applications

BACKGROUND

Traditionally, the dural venous sinuses have been described only in the cranium. However, anecdotally, during various neurosurgical intradural procedures in the lumbosacral spine, we noticed an intradural collection of blood. With no prior studies on this in the extant medical literature, the following anatomic investigation seemed warranted.

METHODS

Twenty fresh frozen adult cadavers were used for the study. The dural sac was exposed and removed. A 30-gauge needle was inserted into the dura mater while not traversing the full thickness of the dura mater. Once the needle was positioned halfway into the thickness of the dura mater, injection of black ink was attempted. Cross-sections of the dural sac were performed, and the sections were stained using hematoxylin and eosin and examined under a light microscope.

RESULTS

Spinal venous sinuses were identified between the L5 and S1 levels in 14 (70%) specimens. Transdural vessels were found through the thickness of the dural sac along its entire circumference, but the spinal venous sinus was only identified in the posterior region of the dural sac in the lumbosacral region (L3 to S1).

CONCLUSIONS

Our study identified a dural venous sinus located in the dorsal lumbosacral region and near the midline. We suggest this structure be called the lumbosacral venous sinus. Although the function of such a sinus is speculative, knowledge of its presence might benefit those interpreting imaging of this region, especially with regional pathology such as dural arteriovenous fistulas.

Idiopathic spinal cord herniation with duplicated dura mater and dorsal subarachnoid septum. Report of a case and review of the literature

Background

Idiopathic spinal cord herniation (ISCH) is a rare condition and its pathogenesis remains unclear. The purpose of this case report is to present an ISCH case with dorsal subarachnoid septum suggesting the pathogenesis of ISCH being adhesions from preexisting inflammation.

Methods

Single case report.

Results

A 60-year-old woman presented with Brown-Séquard syndrome below the level of T6. Magnetic resonance imaging revealed the thoracic spinal cord was displaced ventrally, and the dorsal subarachnoid space was enlarged and had a septum between the spinal cord and dura mater. Intraoperatively, the dorsal dura mater was seen to be adherent and the subarachnoid septum was identified after durotomy. The inner layer defect of the duplicated dura mater was found in the ventral dura mater, through which the spinal cord had herniated. After releasing the septum, the adhesions around the dura mater, and the hiatus, the spinal cord was reduced.

Conclusions

The present case indicates that adhesions around the dura mater can be the pathogenesis of ISCH.

Idiopathic spinal cord herniation: Clinical review and report of three cases

Idiopathic spinal cord herniation (ISCH) is a rare condition, of unknown pathogenesis, that primarily affects the thoracic spinal cord. It is characterized by ventral displacement of the spinal cord through a dural defect. The aim of this study was to review the literature and to present a retrospective single center experience with three cases of ISCH. The literature review analyzed a total of 78 relevant publications on ISCH, which included a total of 171 patients, supplemented with 3 patients treated at our institution. Numerous case reports have demonstrated improvement in clinical outcomes after surgery; however, follow-up is predominantly short, data are incomplete, the condition is frequently misdiagnosed, and it is difficult to predict which patients will benefit from surgery. We identified 159 cases treated with surgical management. The mean symptom duration was 54 months, and the mean follow-up 33 months. The result at follow-up was improved neurological outcome in 74%, unchanged result in 18%, and worse outcome in 8%. There were 15 cases of conservative management, with mean symptom duration 52 months and mean follow-up 33 months. The neurological outcome was unchanged in 100%. ISCH is a rare condition causing progressive thoracic myelopathy, and the natural history is unknown. There is a lack of evidence-based treatment strategies, and the majority of cases are treated with surgical management at diagnosis. Management of ISCH needs to be individualized for each patient, and clinicians should be encouraged to report new cases, standardize case reports, and ensure long-term follow-up.

Spinal cord herniation: management and outcome in a series of 12 consecutive patients and review of the literature

BACKGROUND

Spinal cord herniation is a rare entity that has been recognized and described with increasing frequency in the past few years. It is characterized by herniation of the spinal cord through an anterior dural defect. In their study of 12 cases, the authors attempt to develop management and treatment guidelines for patients suffering from this condition.

METHODS

A retrospective analysis of the medical files was carried out in a series of 12 consecutive patients treated at our Institution between 1998 and 2011 for spinal cord herniation. The clinical, radiological and surgical findings, management and outcome were reviewed.

RESULTS

The male:female ratio was 5:7, with a mean age of 47 years (range 26–71 years). All patients presented a progressively worsening symptomatology. Symptoms at presentation included progressive myelopathy, corticospinal tract sign, algoparesthesia and sphincter dysfunction. The radiological appearance was uniform. All the lesions were located between the T2 and T8 vertebrae. One patient was initially managed conservatively. All patients underwent surgical correction via a posterior approach, with reduction of the herniated spinal cord, the positioning of a muscular autograft to fill the anterior cavity and closure of the dural defect with an artificial dural patch. Six patients showed improvement of preoperative symptomatology at follow-up, while the others remained free from symptom progression.

CONCLUSIONS

The authors present one of the largest studies to date regarding patients with spinal cord herniation and emphasize that the possibility of this condition must be kept in mind when addressing all patients with progressive myelopathy.

Idiopathic thoracic spinal cord herniation: retrospective analysis supporting a mechanism of diskogenic dural injury and subsequent tamponade

BACKGROUND AND PURPOSE

tSCH in the absence of spinal trauma or surgery is a rare disorder for which numerous mechanisms have been proposed. Here, we have conducted an analysis of images in all published reports of idiopathic tSCH and identified evidence supporting a pathogenesis in which anterior dural erosion at thoracic levels generates a CSF leak that pushes adjacent spinal tissue to tamponade the dural defect, causing progressive myelopathy. Additionally, we describe a case of tSCH in which postural headache was a significant symptom before myelopathy. This finding suggests that tSCH pathogenesis may be related to spontaneous intracranial hypotension.

MATERIALS AND METHODS

Published imaging from all available prior case reports in the scientific literature was reviewed to determine whether tSCH occurred at the disk or bone level. The presence of EDF, HNP, or an osteophyte in the spinal canal was determined from review of published images. Additionally, 3 previously unreported cases from the teaching files of our department were assessed by using these criteria.

RESULTS

In greater than two-thirds (47 of 67) of identified cases with published images, tSCH occurred at a disk level. When assessment was possible, EDF, HNP, and osteophytes were present in 26.8%, 30.7%, and 26.2% of cases, respectively. Overall, 52.3% of cases with published images demonstrated evidence of these abnormalities.

CONCLUSIONS

Our analysis of published imaging indicates that tSCH occurs preferentially at spinal levels and with imaging findings consistent with dural injury that support the proposed etiology of this disorder.

The value of intraoperative motor evoked potential monitoring during surgical intervention for thoracic idiopathic spinal cord herniation

OBJECT

Thoracic idiopathic spinal cord herniation (TISCH) is a rare neurological disorder characterized by an incarceration of the spinal cord at the site of a ventral dural defect. The disorder is associated with clinical signs of progressive thoracic myelopathy. Surgery can withhold the natural clinical course, but surgical repair of the dural defect bears a significant risk of additional postoperative motor deficits, including permanent paraplegia. Intraoperative online information about the functional integrity of the spinal cord and warning signs about acute functional impairment of motor pathways could contribute to a lower risk of permanent postoperative motor deficit. Motor evoked potential (MEP) monitoring can instantly and reliably detect dysfunction of motor pathways in the spinal cord. The authors have applied MEPs during intraoperative neurophysiological monitoring (IOM) for surgical repair of TISCH and have correlated the results of IOM with its influence on the surgical procedure and with the functional postoperative outcome.

METHODS

The authors retrospectively reviewed the intraoperative neurophysiological data and clinical records of 4 patients who underwent surgical treatment for TISCH in 3 institutions where IOM, including somatosensory evoked potentials and MEPs, is routinely used for spinal cord surgery. In all 4 patients the spinal cord was reduced from a posterior approach and the dural defect was repaired using a dural graft.

RESULTS

Motor evoked potential monitoring was feasible in all patients. Significant intraoperative changes of MEPs were observed in 2 patients. The changes were detected within seconds after manipulation of the spinal cord. Monitoring of MEPs led to immediate revision of the placement of the dural graft in one case and to temporary cessation of the release of the incarcerated spinal cord in the other. Changes occurred selectively in MEPs and were reversible. In both patients, transient changes in intraoperative MEPs correlated with a reversible postoperative motor deficit. Patients without significant changes in somatosensory evoked potentials and MEPs demonstrated no additional neurological deficit postoperatively and showed improvement of motor function during follow-up.

CONCLUSIONS

Surgical repair of the dural defect is effected by release and reduction of the spinal cord and insertion of dural substitute over the dural defect. Careful monitoring of the functional integrity of spinal cord long tracts during surgical manipulation of the cord can detect surgically induced impairment. The authors' documentation of acute loss of MEPs that correlated with reversible postoperative motor deficit substantiates the necessity of IOM including continuous monitoring of MEPs for the surgical treatment of TISCH.

Idiopathic spinal cord herniation at two separate zones of the thoracic spine: the first reported case and literature review

BACKGROUND CONTEXT

Idiopathic spinal cord herniation (ISCH) is a rare cause of progressive myelopathy. Preoperative diagnosis can be made with magnetic resonance imaging (MRI). Many surgical techniques have been applied by various authors, and ISCH is usually reversible by surgical treatment.

PURPOSE

To present a case of ISCH in two separate zones at two thoracic levels. To our knowledge, this is the first such case to be published in English literature. We also discuss the clinical findings, surgical procedures, and surgical outcomes for other previously reported cases of ISCH in the literature.

STUDY DESIGN

Case report.

METHODS

A 52-year-old woman with bilateral lower extremity weakness underwent thoracic MRI, which revealed transdural spinal cord herniation at two separate zones, namely, the T4-T5 and T5-T6 intervertebral disc levels.

RESULTS

During surgery, the spinal cord was reduced, the two separate dural defects were connected, and the new single defect was restored then reinforced with a thin layer of fascial graft. The posterior dural defect was then closed with interrupted stitches. The patient's neurologic status was characterized by no changing of the preoperative motor status. Follow-up MRI scans showed that the cord was replaced in the dural sac and showed cord hyperintensity in the herniation levels. The patient could move with a cane at the sixth month postoperatively.

CONCLUSIONS

Idiopathic spinal cord herniation is a rare clinical condition that should be considered in the differential diagnosis of paraplegia. Although progression of neurologic deficits can be very slow, reduction of the spinal cord and repair of the defect are crucial to stop or reverse the deterioration. The outcome for patients who initially have Brown-Séquard syndrome is significantly better than for patients who presented with spastic paralysis. To our knowledge, this case study represents the first reported instance in which two separate anterior dural defects caused two levels of anterior spinal cord herniation.

Idiopathic ventral spinal cord herniation: a rare presentation of tethered cord

Idiopathic ventral spinal cord herniation is a rare condition that has been increasingly reported in the last decade. The natural history and optimal management have yet to be defined. Therefore, debate exists regarding the pathogenesis and surgical management of this condition. The purpose of this review article is to further educate neurosurgeons about the surgical techniques and outcomes associated with treating this rare and often misdiagnosed condition.

Image classification of idiopathic spinal cord herniation based on symptom severity and surgical outcome: a multicenter study

Object

The purpose of this study was to provide the first evidence for image classification of idiopathic spinal cord herniation (ISCH) in a multicenter study.

Methods

Twelve patients who underwent surgery for ISCH were identified, and preoperative symptoms, severity of paralysis and myelopathy, disease duration, plain radiographs, MR imaging and CT myelography findings, surgical procedure, intraoperative findings, data from spinal cord monitoring, and postoperative recovery were investigated in these patients. Findings on sagittal MR imaging and CT myelography were classified into 3 types: a kink type (Type K), a discontinuous type (Type D), and a protrusion type (Type P). Using axial images, the location of the hiatus was classified as either central (Type C) or lateral (Type L), and the laterality of the herniated spinal cord was classified based on correspondence (same; Type S) or noncorrespondence (opposite; Type O) with the hiatus location. A bone defect at the ISCH site and the laterality of the defect were also noted.

Results

Patients with Type P herniation had a good postoperative recovery, and those with a Type C location had significant severe preoperative lower-extremity paralysis and a significantly poor postoperative recovery. Patients with a bone defect had a significantly severe preoperative myelopathy, but showed no difference in postoperative recovery.

Conclusions

The authors' results showed that a Type C classification and a bone defect have strong relationships with severity of symptoms and surgical outcome and are important imaging and clinical features for ISCH. These findings may allow surgeons to determine the severity of preoperative symptoms and the probable surgical outcome from imaging.

Operative treatment of anterior thoracic spinal cord herniation: three new cases and an individual patient data meta-analysis of 126 case reports

OBJECTIVE

Anterior thoracic spinal cord herniation is a rare cause of progressive myelopathy. Much has been speculated about the best operative treatment. However, no evidence in favor of any of the promoted techniques is available to date. Therefore, we decided to analyze treatment procedures and treatment outcomes of anterior thoracic spinal cord herniation to identify those factors that determine postoperative outcome.

METHODS

An individual patient data meta-analysis was conducted, focusing on age, gender, vertebral segment of herniation, preoperative neurological status, operative interval, operative findings, operative techniques, intraoperative neurophysiological monitoring, postoperative imaging, neurological outcome and follow-up. Three cases from our own institution were added to the material collected. Bivariate analysis tests and multivariate logistic regression tests were used so as to define which variables were associated with outcome after surgical treatment of anterior thoracic spinal cord herniation.

RESULTS

Brown-Séquard syndrome and release of the herniated spinal cord appeared to be strong independent factors, associated with favorable postoperative outcome. Widening of the dura defect is associated with the highest prevalence of postoperative motor function improvement when compared with the application of an anterior dura patch (P < 0.036).

CONCLUSION

Most patients with anterior thoracic spinal cord herniation require operative treatment because of progressive myelopathy. Patients with Brown-Séquard syndrome have a better prognosis with respect to postoperative motor function improvement. In this review, spinal cord release and subsequent widening of the dura defect were associated with the highest prevalence of motor function improvement. D-wave recording can be a very useful tool for the surgeon during operative treatment of this disorder.

Idiopathic spinal cord herniation: case report and review of the literature

BACKGROUND

Idiopathic spinal cord herniation (ISCH) is a rare cause of progressive myelopathy frequently present in Brown-Séquard syndrome. Preoperative diagnosis can be made with magnetic resonance imaging (MRI). Many surgical techniques have been applied by various authors and are usually reversible by surgical treatment.

METHODS

Case report and review of the literature.

FINDINGS

A 45-year-old woman with Brown-Séquard syndrome underwent thoracic MRI, which revealed transdural spinal cord herniation at T8 vertebral body level. During surgery the spinal cord was reduced and the ventral dural defect was restorated primarily and reinforced with a thin layer of subdermal fat. The dural defect was then closed with interrupted stitches.

RESULTS

Although neurologic status improved postoperatively, postsurgical MRI demonstrated swelling and abnormal T2-signal intensity in the reduced spinal cord. Review of the English language literature revealed 100 ISCH cases.

CONCLUSIONS

ISCH is a rare clinical entity that should be considered in differential diagnosis of Brown-Séquard syndrome, especially among women in their fifth decade of life. Outcome for patients who initially had Brown-Séquard syndrome was significantly better than for patients who presented with spastic paralysis. Although progression of neurologic deficits can be very slow, reduction of the spinal cord and repair of the defect are crucial in stopping or reversing the deterioration.

Diagnosis and treatment of spinal cord herniation: a combined experience

OBJECT

Idiopathic spinal cord herniation (ISCH) is an uncommon clinical entity typically presenting with lower-extremity myelopathy. Despite the existence of 85 ISCH cases in the literature, misdiagnosis and delayed diagnosis remain a major concern.

METHODS

The authors conducted a retrospective review of patients who underwent surgery for ISCH at their institutions between 1993 and 2004. Seven patients were treated for ISCH, five in New York and two in Buenos Aires. The patients' ages ranged from 32 to 72 years. There were three men and four women. The interval between the onset of symptoms and surgery ranged from 12 to 84 months (mean 42.1 months). Preoperatively, spinal cord function in four patients was categorized as American Spinal Injury Association (ASIA) Grade D, and that in the other three patients was ASIA Grade C. In all patients a diagnosis of posterior intradural arachnoid cyst had been rendered at other institutions, and three had undergone surgery for the treatment of this entity. In all cases, the herniation was reduced and the defect repaired with a dural patch. The follow-up period ranged from 10 to 147 months (mean 49.2 months). Clinical recovery following surgery varied; however, there was no functional deterioration compared with baseline status. Syringomyelia, accompanied by neurological deterioration, developed post-operatively in two patients at 2 and 10 years, respectively.

CONCLUSIONS

Patients presenting with a diagnosis of posterior intradural arachnoid cyst should be evaluated carefully for the presence of an anterior spinal cord herniation. Based on the authors' literature review and their own experience, they recommend offering surgery to patients even when neurological compromise is advanced.