Ventral tethering in split cord malformation

lVentral tethering-is the prognosis worse than in dorsal tethering in the dysraphic spine?

OBJECTIVE

To compare cases of dysraphism with ventral tethering of cord with those with dorsal tethering and to find out any differences in the outcome of surgery in them.

METHODS

We collected the data of 188 consecutively operated tethered cord patients at our institute in the past 7 years and divided them into ventral tethering and dorsal tethering groups. Those that we felt had both dorsal and ventral tethering were excluded. Their preoperative clinical, radiological, and baseline neurophysiological parameters as well as postoperative clinical and radiological parameters were analyzed in a retrospective study.

RESULTS

Among the 188 tethered cord patients, 52 (28%) had ventral tethering and 136 (72%) had posterior tethering. Preoperative neurodeficit and cord signal changes as well as absent baseline MEP (of any one muscle) were significantly more associated with ventral tethered cord than the dorsal tethered cord. The neurological deterioration after surgery occurred significantly in the ventral tethered cord group than in the dorsal tethered cord group. Also, the postoperative MRI had more incomplete detethering cases in the ventral group than in the dorsal tethered cord group.

CONCLUSION

Ventral tethered cord is more likely to present with preoperatively neurological deficits. It should be carefully identified in the preoperative MRI, so that the intraoperative difficulties in complete detethering and postoperative deterioration can be anticipated.

Double spinal cord tethering and congenital kyphosis in a 4-year-old boy

PURPOSE

Congenital kyphosis (CK) is an uncommon condition that develops due to a defect of formation or segmentation of one or more vertebrae during the first weeks of embryonic life and can be frequently associated with abnormalities of the spinal cord. Meningocele manqué (MM) is a rare congenital malformation consisting of intradural fibrous bands tethering the spinal cord, oftentimes in combination with a split cord malformation. The aim of this manuscript is to describe combined surgical management of a rare case of CK associated with double spinal cord tethering.

STUDY DESIGN

Case report.

METHODS

We report the case of a 4-year-old boy presenting with a combination of congenital kyphosis due to L2 fully segmented posterior hemivertebra and double spinal cord tethering, at the level of the filum terminale and at L1-L2 due to an intradural ventral fibrous band.

RESULTS

Spinal cord detethering and L2 hemivertebra resection with kyphosis correction were achieved with a single stage procedure. Segmental kyphosis was corrected from 45° to 11° post-operatively. Apart from a transitory sensory impairment, no immediate or delayed complications were noted and, at 2 years follow-up, correction and spinal alignment were stable.

CONCLUSION

To the best of our knowledge, this is the first case to report the simultaneous occurrence of congenital kyphosis and double spinal cord tethering due to MM and tethering of the filum terminale. Our case report shows that surgical correction of the deformity and spinal cord detethering can be safely and effectively achieved during the same surgical procedure.

Gastrulation and Split Cord Malformation

Split cord malformation (SCM) is a rare form of closed spinal dysraphism, in which two hemi-cords are present, instead of a single spinal cord. SCM is categorised into type 1 and type 2. Type 1 SCM is defined by the presence of a bony or osseocartilaginous spur between the hemi-cords, whereas type 2 SCM has no bony spur, and the two hemi-cords are contained within a single dura. In this chapter, we present the putative mechanisms by which SCM arises, including gastrulation defects and Pang's unified theory. The typical and rare clinical presentations and variations are described. Finally, we outline the step-by-step surgical approach to both SCM 1 and 2 and the overall prognosis of both conditions.

Split Notochord Syndrome with Spinal Column Duplication and Spinal Cord Lipoma: A Case Report

Background and Importance: Split notochord syndrome (SNS) is an exceedingly rare type of spinal dysraphism. SNS is sometimes associated with other congenital dysraphic defects but, as in our case, the association with spinal cord lipoma, tethered cord, and spinal deformity in the form of spinal column duplication would be exceedingly rare. Herein, the authors report a three-year-old child presented with SNS associated with complex spinal deformity and other associated congenital anomalies. The patient underwent microsurgical release of the tethering element with excellent short- and long-term outcomes. Clinical Presentation: A male newborn with healthy nonconsanguineous parents was born with multiple gastrointestinal and genitourinary anomalies, and duplicated vertebral columns at the lumbosacral area consistent with split notochord syndrome. The patient was initially managed for the gastrointestinal and genitourinary anomalies. As there was no obvious neurological deficit initially, the neurosurgical intervention was postponed till the child reached 30 months of age, when he underwent uneventful release of both spinal cords at their spit point. Conclusions: SNS is an exceedingly rare developmental anomaly that is usually associated with varying degrees of complex congenital dysraphic defects. Early clinical diagnosis, understanding of the pathophysiology of spinal cord tethering, and microsurgical cord untethering are the important steps in optimal management.

A Type II Split Cord Malformation in an Adult Patient: An Operative Case Report

BACKGROUND AND IMPORTANCE

Split cord malformations (SCMs) are rare conditions in which the spinal cord is split into two hemicords within either a single thecal sac or two separate thecal sacs. The hemicords are typically split by a bony or fibrous structure. We present an adult patient who presented with a type II SCM with tethered cord. This is the first case of such a presentation with an accompanying intraoperative video. Unusual features of the case were the presence of an incomplete fibrous septum and lack of a discrete filum terminale.

CLINICAL PRESENTATION

A 50-yr-old woman presented with back pain, radiculopathy, urinary urgency, and episodic fecal incontinence. Her exam was notable for weakness of the right extensor hallicus longus. Imaging showed an SCM extending from L3 to S1, a fibrous septum located at L4-5, and a low-lying conus at S4. She was treated with a decompressive L3-S4 laminectomy and disconnection of all the dural attachment points. She required lumbar drain placement postoperatively and reoperation for wound dehiscence and persistent pseudomeningocele. At the time of last follow-up, she was neurologically intact with improvement in bowel/bladder function.

CONCLUSION

SCM is an uncommon presentation in adults and is often accompanied by findings of skin stigmata, tethered cord, and other central nervous system/skeletal anomalies. Obtaining full multimodal imaging is critical to understanding subtle anatomic variations that can pose operative challenges. We report the treatment of an adult patient with type II SCM, and provide an intraoperative video demonstrating the removal of an incomplete midline fibrous septum.

Chinese expert consensus on diagnosis and management of split cord malformation

Split cord malformation (SCM) is a neural tube defect that the spinal cord is longitudinally separated into two hemicords with individual functions, which causes severe spinal cord impairment and sensorimotor deficit. As a kind of myelodysplasia and a special type of tethered cord syndrome, SCM is not widely understood, and common issues in the diagnosis and treatment of SCM should be clarified. In this paper, the Chinese Split Cord Malformation Working Group made a consensus for SCM on embryopathogenesis and types, clinical presentations, neuroimaging assessment, indications and principle of the surgery, surgical techniques and nuances, and prognosis and follow up.

Ventral and dorsal tethering bands of the spinal cord in the same patient: a case report

Fibrous bands are one of the causes of tethered cord syndrome and these can be located on the dorsal or more rarely, ventral aspect of the dura mater. We report a case of dorsal and ventral tethering bands in the same patient found at surgery for tethered cord syndrome. Such fibrous bands restrict normal movement of the spinal cord and lead to a variety of neurological symptoms. To our knowledge, we report the first case of dorsal and ventral tethering bands of the spinal cord in the same patient. This case report aims to increase awareness of such anatomical variations and emphasize the importance of meticulous surgical dissection in order to identify such bands.

Meningocele manqué: a comprehensive review of this enigmatic finding in occult spinal dysraphism

The term meningocele manqué (MM) was coined in 1972 to describe a broad range of surgical findings characterized by intradural bands tethering neural structures to the dorsal dura. Over the following decades, reports continued to lump intradural tethering bands associated with a variety of comorbidities under the umbrella term MM. In more recent years, disorders previously called MM have been identified as embryologically distinct and were reclassified. While this sectioning continues, there remains a set of intradural tethering disorders for which no better term than MM exists. Herein, we comprehensively review the literature surrounding MM, including embryological disorders, clinical, radiographic, and surgical presentation, as well as alternative classification methods and MM treatment.

Duplicated filum terminale in the absence of split cord malformation: a potential cause of failed detethering procedures

INTRODUCTION

A duplicated filum terminale appears to be a rare finding in the absence of a split cord malformation. Herein, we discuss this finding and its potential dysembryology.

CASE REPORTS

We report two cases of duplicated filum terminale without split cord malformation. The first case presented as an incidental finding with thickened filum terminale. At time of surgery, a thickened filum was resected and a smaller size filum was transected and both were confirmed with pathologic examination. The second case presented with a lumbar skin hemangioma. Screening MRI showed a duplicated filum terminale with fat signal in both structures. Pathology also confirmed the diagnosis of two fila terminalia.

CONCLUSIONS

The neurosurgeon should consider the possibility of two fila terminalia during operation to transect a single filum for tethered spinal cord.

Surgical manifestations of thoracic arachnoid pathology: series of 28 cases

Object

Various pathologies involving the thoracic arachnoid mater uniformly manifest as thoracic myelopathy and may present a significant management dilemma. The authors undertook this study to assess outcome in cases of thoracic myelopathy due to thoracic arachnoid pathology.

Methods

The authors have cared for and followed 28 patients with thoracic myelopathy from thoracic arachnoid pathology over the last 17 years. A chart review and contemporary follow-up of these patients was performed and outcomes were reported.

Results

Patients with thoracic myelopathy from thoracic arachnoid pathology often have improvement in their condition after surgical decompression/detethering procedures. While not universal, patients in this series had improvement in mJOA scores at 1 year after surgery (p = 0.0001) and at last follow-up (p = 0.04). Results indicated that across a wide variety of pathologies the extent of thoracic spinal cord involvement is a predictor of the disease course and outcome. Comparison of the group of patients with cord involvement limited to 2 vertebral segments (short-segment pathology) versus the group with cord tethering of more than 2 segments (long-segment pathology) showed that patients in the short-segment group more frequently had ventral or dorsal arachnoid bands (p = 0.003), more frequently had signal change in the cord on MRI (p = 0.02), and less frequently presented with a syrinx (p = 0.02), and a smaller percentage of patients in this group underwent reoperation (p = 0.02). While patients with short-segment pathology typically improved after a single operative intervention, patients with long-segment pathology typically improved after multiple operations, frequently for CSF diversion.

Conclusions

Thoracic arachnoid pathology causing thoracic cord dysfunction and myelopathy is varied, has multiple etiologies, and can be difficult to treat over the long term. Surgical management, when indicated, is case specific. Serial long-term follow-up is essential to document enduring clinical and radiographic success.

Split cord malformation types I and II: a personal series of 131 patients

PURPOSE

A personal series of 131 patients with split cord malformation (SCM) operated on is presented.

METHODS

Age, gender, symptoms and signs, radiological and operative findings, complications, associated anomalies, outcome, and pathological specimens were analyzed.

RESULTS

There were 88 girls (73 %) and 43 boys (27 %). The female predominance was slightly more remarkable in type I SCMs than in type II SCMs. The presenting symptoms can be summarized as skin lesions, spina bifida aperta, scoliosis or kyphoscoliosis, sphincter disturbance, foot deformities and weakness, and/or atrophy in the lower extremities. The ages of patients with neurological deficits and orthopedic deformities were significantly older than those without deficits (P = 0.030). The duration of symptoms was longer in the patients with neurological deficits and orthopedic deformities than that in those without deficits (P = 0.00095). In six patients, composite SCMs were present. Only one patient with a type II SCM did not have an associated spinal cord lesion. A type I SCM was more frequently encountered in patients with spina bifida (P < 0.0005). Transient postoperative complications were seen in 29 patients (22 %). There was no permanent complication. Retethered cord syndrome developed in five patients with a type I SCM.

CONCLUSIONS

The risk of neurological and orthopedic deficits increases with the age of the patient. The risk of permanent deficit after surgery is very low. The whole spine must be examined for additional lesions. All patients should be surgically treated when diagnosed, especially before the development of orthopedic and neurological manifestations, and all associated lesions should also be treated at the same session.

Non-fusion and growing instrumentation in the correction of congenital spinal deformity associated with split spinal cord malformation: an early follow-up outcome

STUDY DESIGN

A retrospective case review.

INTRODUCTION

To evaluate the safety and efficacy of the non-fusion technique in achieving and maintaining the proper correction for congenital spinal deformity (CSD) and allowing normal spinal growth in patients with split spinal cord malformation (SSCM).

MATERIALS AND METHODS

Seven patients who had CSD and SSCM were adopted, with a mean age of 8 years. All the patients in this study received Halo-gravity traction (HGT) prior to expansion of the spine and instrumentation with vertical expandable titanium prosthetic rib, growing rod or their hybrid. Five of them underwent opening wedge thoracoplasty simultaneously. And the two patients with type I SSCM underwent bony spur excision in the initial surgery before corrective manipulation. Then all the patients received a lengthened operation every six months. Changes of their major curve and length of T1-S1 spine were measured, and complications, neurological status were recorded. All the patients were followed up with an average of 32.6 months.

RESULTS

Their mean major curve improved from 90.1° to 58.6° with a correction rate of 34.9 %. The T1-S1 length increased from 26.3 to 34.7 cm at final follow-up. Especially, one of the type I SSCM patients whose neurological deterioration was found preoperatively was significantly improved.

CONCLUSION

Preoperative Halo-gravity traction followed by non-fusion and growing instrumentation may be effective and safe for young children of CSD associated with SSCM. But it is an ongoing study and additional large multicenter studies are necessary to further assess the safety and efficacy of non-fusion and growing instrumentation.

Tethered cord syndrome in adults

OBJECT

The treatment of tethered cord syndromes in adults is discussed regarding the natural history and surgical indications. The author analyzes data obtained in patients who were diagnosed with a tethered cord in adulthood and either underwent surgical or conservative therapy between 1991 and 2009.

METHODS

Since 1991, data obtained in 2515 patients with spinal cord pathologies were entered into the spinal cord database, and prospective follow-up was performed through outpatient visits and questionnaires. Of the 2515 patients, 85 adults with a tethered cord syndrome formed the basis of this study. The tethering effect was caused either by a split cord malformation, a thick filum terminale, a conus medullaris lipoma with extradural extension, or various combinations of these mechanisms. The mean age of the patients was 46 ± 13 years (range 23-74 years) and the mean follow-up duration was 61 ± 62 months. Two groups were distinguished based on the absence (Group A, 43 patients) or presence (Group B, 42 patients) of an associated lipoma or dysraphic cyst (that is, dermoid, epidermoid, or neurenteric cyst). Surgery was recommended for patients with symptoms only. Short-term results were determined within 3 months of surgery, whereas long-term outcomes (clinical recurrences) were evaluated using Kaplan-Meier statistics.

RESULTS

For all patients, pain was the most common major complaint. Severe neurological deficits were rare. In Group A, 20 of 43 patients underwent surgery, whereas in Group B 23 of 42 patients underwent surgery. Among individuals who did not undergo surgery, 17 patients refused surgery and 25 patients underwent recommended conservative treatment. Short-term postoperative results indicated a significant improvement of pain and a stabilization of neurological symptoms. Long-term results showed a good prognosis in patients in whom first-time (that is, nonrevision) surgery achieved successful untethering, with a 10-year rate of neurological stabilization in 89% of Group A and a 10-year rate of neurological stabilization in 81% of Group B patients. The benefit of secondary operations in Group B was limited, with eventual clinical deterioration occurring in all patients within 10 years. For patients treated conservatively, follow-up information could be obtained in 33 of 42 patients. Twenty-eight patients remained in stable clinical condition. Only 5 of the conservatively treated patients experienced clinical deterioration over time; in 4 of these individuals with deterioration, surgery had been recommended but was refused by the patient. The clinical recurrence rate in all conservatively treated patients was 21% after 10 years. With a recommendation for surgery this figure rose to 47% within 5 years.

CONCLUSIONS

Surgery in adult patients with a tethered cord syndrome should be reserved for those with symptoms. In surgically treated patients, pain relief can often be achieved, and long-term neurological stabilization tends to persist more often than it does in conservatively treated patients. A conservative approach is warranted, however, in adult patients without neurological deficits. Revision surgery in patients with complex dysraphic lesions should be performed in exceptional cases only.

Limited dorsal myeloschisis: a distinctive clinicopathological entity

BACKGROUND

Limited dorsal myeloschisis (LDM) is a distinctive form of spinal dysraphism characterized by 2 constant features: a focal "closed" midline defect and a fibroneural stalk that links the skin lesion to the underlying cord. The embryogenesis is hypothesized to be incomplete disjunction between cutaneous and neural ectoderms, thus preventing complete midline skin closure and allowing persistence of a physical link (fibroneural stalk) between the disjunction site and the dorsal neural tube.

OBJECTIVE

To illustrate these features in 51 LDM patients.

METHODS

All patients were studied with magnetic resonance imaging or computed tomography myelography, operated on, and followed for a mean of 7.4 years.

RESULTS

There were 10 cervical, 13 thoracic, 6 thoracolumbar and 22 lumbar lesions. Two main types of skin lesion were saccular (21 patients), consisting of a skin-base cerebrospinal fluid sac topped with a squamous epithelial dome, and nonsaccular (30 patients), with a flat or sunken squamous epithelial crater or pit. The internal structure of a saccular LDM could be a basal neural nodule, a stalk that inserts on the dome, or a segmental myelocystocele. In nonsaccular LDMs, the fibroneural stalk has variable thickness and complexity. In all LDMs, the fibroneural stalk was tethering the cord. Twenty-nine patients had neurological deficits. There was a positive correlation between neurological grade and age, suggesting progression with chronicity. Treatment consisted of detaching the stalk from the cord. Most patients improved or remained stable.

CONCLUSION

LDM is a distinctive clinicopathological entity and a tethering lesion with characteristic external and internal features. We propose a new classification incorporating both saccular and flat lesions.

Tethering tracts in spina bifida occulta: revisiting an established nomenclature

OBJECT

The goal of the present study goal was to systematically confirm the previously recognized nomenclature for tethering tracts that are part of the spectrum of occult spinal dysraphic lesions.

METHODS

The tethering tract in 20 patients with spina bifida occulta underwent histological examination with H & E staining and epithelial membrane antigen (EMA) immunolabeling, and additional selected specimens were stained with Masson trichrome.

RESULTS

All tethering tracts contained fibrous connective tissue. Four tracts were lined with epithelial cells and either originated within a dermoid cyst, terminated at a skin dimple/sinus opening, or had both of these characteristics. No tethering tracts exhibited EMA positivity or meningeal elements. Although all tethering tracts originated in juxtaposition to the spinal cord, their termination sites were variable.

CONCLUSIONS

Based on histological findings and presumed embryological origin, the authors broadly classified tethering tracts terminating within the dura mater, epidural space, or lamina as "short tethering tracts" (STTs). The STTs occurred mostly in conjunction with split cord malformations and had a purely fibrous composition. Tethering tracts terminating superficial to the overlying lamina were classified as "long tethering tracts" (LTTs), and the authors propose that these are embryologically distinct from STTs. The LTTs were of two varieties: epithelial and nonepithelial, the former being typically associated with a skin dimple or spinal cord (epi)dermoid cyst. In fact, analysis of the data suggested that not every tethering tract terminating in or on the skin should be classified as a dermal sinus tract without histological confirmation, and because no evidence of meningeal tissue-lined tracts was detected, the use of the term "meningocele manqué" may not be appropriate.