An unusual case of dorsally situated bony spur in a lumbar split cord malformation

Dorsal bony spur in pediatric split cord malformations: eight-year experience from a tertiary care hospital

INTRODUCTION

Dorsal spurs in Type I split cord malformations (SCM-I) are infrequent findings. The pathogenesis of the same is debatable. The objective of this study is to analyze our experience with SCM-I patients having dorsal bony spurs.

METHODOLOGY

Retrospective analysis of SCM patients operated from 2010 to 2017 was performed. Their demographic profile, clinic-radiological features, operative findings, and outcome following surgery were recorded.

RESULTS

Twenty-four cases of Type I SCM harboring dorsal bony spurs were identified with mean age of 4.96 years. The commonest split site was lumbar, documented in 62.5%. Scoliosis was observed in 58.3%. Pre-operative neurological deficits were seen in 66.6% cases with asymmetric weakness of limbs seen in 16.6%. There was no new neurological deficit observed post-operatively.

CONCLUSIONS

This is the largest series of dorsal spurs occurring in SCM, reported in literature so far. Meticulous pre-operative evaluation and imaging are important to identify dorsal spurs for appropriate management and good clinical outcome. Differentiating dorsal spur from ventral spur is important as it has a bearing on surgical approach.

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.

Type 1.5 Split Cord Malformation : A New Theory of Pathogenesis

To report two cases of type 1.5 split cord malformation (SCM), a subtype of SCM with combined characteristics of types I and II and to review the relevant literature and propose a new possible pathogenetic theory for type 1.5 SCM. A 52-year-old woman had hemicords within a single dural sac with a dorsal bony septum at the L5 level. A 9-year-old boy had hemicords within a single dural sac with a ventral bony septum and fibrous extension at the L3 level. Both patients underwent microsurgical treatments for removing the bony septum, detethering the spinal cord, and sectioning the filum terminale. The surgical procedure revealed an extradural partial bony septum and hemicords within an intact single dural sac in each patient. Both patients were discharged from the hospital without de novo nerve dysfunction. Published cases have validated that types I and II SCM can overlap. We recommend recent type 1.5 SCM as a normative terminology for this overlapping SCM and report two rare cases of this SCM. We propose an associated pathogenesis consisting of uneven distribution and regression to explain type 1.5 SCM. Furthermore, we postulate that the amount of condensing meninx primitiva might determine whether the left bony septum has fibrous extensions to the opposite dura in type 1.5 SCM.

Type 1.5 Split Cord Malformations: An Uncommon Entity

BACKGROUND

Split cord malformations (SCMs) are among the rare congenital spinal anomalies. In 1992, Pang et al. proposed the unified theory of embryogenesis and explained the formation of SCM type 1 and 2. This theory has been widely accepted in the neurosurgical literature, backed by several studies. However, there have been reports in the literature that defy both the classification as well as the formation of SCMs, based on the unified theory of embryogenesis. We report a case of SCM that does not fit into this classification scheme and try to elucidate its embryologic basis, with review of the relevant literature. We also attempt to include this variety into the existing classification system of SCMs.

CASE DESCRIPTION

An 11-year-old boy presented with low backache after trivial trauma. He was neurologically intact. Imaging showed low-lying tethered cord and a midline ventral bony spur (D12, L1) with a single dural sac encasing both the hemicords. Surgical exploration showed a ventral bony spur with 2 hemicords, enclosed in a single dural tube. Excision of the bony spur and detethering of the filum terminal were performed. The postoperative course was uneventful and the patient was discharged satisfactorily.

CONCLUSIONS

SCMs possibly represent a continuum of changes beginning at the gestational age of days 20-30. Terminology such as mixed or intermediate type is used to denote SCMs that show features of both type 1 and type II. We prefer using type 1.5 SCMs for all such cases, thereby avoiding confusion and maintaining uniformity in the nomenclature. However, further experimental studies are required to substantiate our understanding of these complex embryologic anomalies on the basis of current hypotheses.

Type 1 Split Cord Malformation: The Significance of the 3D Orientation of the Bony Spur, Its Clinical Relevance, and Surgical Nuances

Background:

Split cord malformation (SCM) remains an important cause of tethered cord syndrome. SCM type 1, wherein a bony spur separates the two dural sacs, represents a challenging condition to treat. The management can be further complicated by the other associated dysraphic states in the same patient. The bony spur at the level of split cord has been variably classified in the literature. There is, however, a paucity of literature dealing with the three-dimensional disposition of the bony spur and its clinical and operative implications.

Materials and Methods:

Our study included 50 patients (male/female = 24:26) of SCM type 1. The orientation of bony spur was categorized into ventral complete, ventral incomplete, and dorsal types along with simultaneous assessment of their direction in sagittal and axial planes in multiplanar computed tomography (CT) scan. Surgical plan was individualized according to each patient’s morbid anatomy.

Results:

The most common site of bony spur was lumbar region (n = 24). Twenty-four (48%) patients had ventral complete type spur, 19 (38%) had ventral incomplete type, and 7 (14%) had dorsal bony spur. Dorsal bony spurs presented with a greater incidence of motor symptoms (71.4%) and bladder disturbances (28.5%), whereas the ventral incomplete type of bony spur was predominantly associated with sensory symptoms (42.1%). Patients with dorsal bony spurs showed better postoperative outcomes when compared to their ventral counterparts.

Conclusion:

Multiplanar assessment of the bony spur using CT scan helps in surgical drilling and improves the outcome. The dorsal SCM variety showed better clinical outcomes when compared to their ventral bony spurs.

Complex spinal dysraphism: myelomenigocele associated with dorsal bony spur, split cord malformation type I, syringomyelia, lipoma and tethered cord

Variations in split cord malformation (SCM) are known. However, association of SCM type I with myelomeningocele along with same level dorsal bony spur has not been described previously. We report a 1-year old male child who presented with these findings with associated syringomyelia, lipoma and tethered cord.

An Unusual Case of Split Cord Malformation with Simultaneous Ventral and Dorsal Bony Spur at a Single Site: A Technical Challenge

Split cord malformation (SCM) with simultaneous ventral and dorsal bony spur at a single site is an extremely rare entity with only one other case reported so far. We present a second such case in a 13-month-old female child, who presented with a skin dimple over the lumbar region with overlying hairy patch without any associated lower limb weakness or urinary complaints. Imaging demonstrated a complex Type I SCM with simultaneous ventral and dorsal bony spur at L4-L5 level. Intraoperatively, the patient was confirmed to have a Type Ic SCM with a ventrally based bony spur going dorsally to attach on the hypertrophied posterior arch of L4 and a dorsal spur going ventrally to attach on the L4 vertebral body. After meticulous microsurgical excision of the spur, the child was stable and developed no fresh neurological deficits. We discuss the relevant surgical implications and possible embryological mechanisms involved in such a complex SCM.

A unique case of split cord malformation type 1 with three different types of bony spurs

Split cord malformation (SCM) is a rare congenital anomaly. The presence of bony spurs seen in type 1 SCM are usually partial and unequivocally are found attached to the dorsal surface of the vertebral body. We present here a unique case of SCM where the bony spur was found attached to the ventral aspect of the posterior arch and there were three different types of spurs (Type 1A, 1B and 1C) in the same patient.

Concurrent split cord malformation and teratoma: dysembryology, presentation, and treatment

Split cord malformation (SCM) is a rare form of spinal dysraphism in which the spinal cord is divided in the sagittal plane, forming a double neural tube. In addition to being associated with a variety of malformations, SCM may occur with spinal cord tumors, with only exceptional cases involving teratomas. As only eight patients with a teratoma associated with SCM have been reported, their presentation characteristics and treatment are currently unclear. We review the literature of all patients with SCM with concurrent spinal teratoma, discuss the potential dysembryology, and report the first case of SCM with concurrent spinal teratoma in an elderly patient. The mean age of those with concurrent SCM and teratomas was 39.4 years, with 55.6% occurring in females. The lumbar spine was the most frequent location for teratomas (66.7%), with the Type II malformation more commonly occurring with these tumors (75%). The duration of symptoms varied widely, ranging from 1 month to 5 years, with the average duration being nearly 2 years. Back pain (87.5%) and lower extremity weakness (75%) were the most common presenting symptoms. As SCM may be associated with progressive neurological deterioration and teratomas can contain immature or malignant components, surgery should be attempted with the goal of gross total resection. Nonetheless, in patients with a concurrent tumor and spinal dysraphism, spinal teratomas should be considered in the differential diagnosis. Gross total resection of these lesions may be safely achieved even in the presence of SCM using intraoperative electrophysiologic monitoring.

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.

Split cord malformation with dorsally located bony spur: Report of four cases and review of literature

Split cord malformations (SCM) with a dorsally located bony spur are a very rare entity. The authors report a series of four such cases. The literature is reviewed regarding the pathogenesis and management of this uncommon variant of SCM. The presenting features include - scoliosis with motor and autonomic dysfunction (n = 1), scoliosis with cutaneous patch (n = 1), hypertrichotic area (n = 1), and motor deficits alone (n = 1). The location of spur was thoracic and lumbar in two patients (50%) each. Low-lying conus was present in three patients. Long segment syrinx was present in one patient. With respect to the bony anomalies, two patients had a hypertrophied posterior arch (HPA) and one patient had a dysraphic spine. All patients underwent surgical excision of the spur with detethering, if a low-lying conus was present. Two patients developed transient worsening of the neurological status after surgery which recovered at the time of the last follow-up; in both these patients, there was a HPA and a low-lying conus. Surgical excision of the spur with detethering of filum, in cases of low-lying conus, is the treatment of choice. Risk of post-operative worsening of the neurological status is increased in cases in which there is concomitant presence of HPA.

Split cord malformations: A two years experience at AIIMS

Background:

Over a 2-year period, 2008-2009, a total of 53 cases of split cord malformation (SCM) were treated at the All India Institute of Medical Sciences (AIIMS). This study is a retrospective analysis of clinical features, radiological findings, and surgical outcome of these patients.

Materials and Methods:

During this period, 53 cases of SCM were treated at AIIMS. They constitute around 27% of all spinal dysraphism surgeries performed at the department of Neurosurgery, AIIMS; as 200 cases of spinal dysraphism were operated during the study period. The data was obtained from case files, operation notes, discharge summaries, and follow-up files.

Observations:

There were 30 cases of SCM type I and 23 cases of type II SCM. Seven patients were adult above 18 years of age. Except 7 patients, remaining 46 were symptomatic. Bony deformity of spine was recorded in 24 patients; of them, 19 had scoliosis and 4 had kyphosis. Deformity of foot was recorded in 10 patients. Thirteen patients had hypertrichosis, while four had dermal sinus. Magnetic resonance imaging (MRI) was performed in all patients. MRI revealed syringomyelia in 14 patients; however, only one patient had associated Chiari malformation. Six patients had meningomyelocele. Intra-operative; thick filum was noticed in 10 cases and in another 9 cases, there was filum lipoma. Dermoid was encountered in 4 patients, one patient had epidermoid tumor. Site of split was thoracic in 22, followed by lumbar region in 21 patients. Only 3 patients had split in cervical spinal cord. Seven patients had two separate splits at two different levels. Two patients had posteriorly located bony spur. All patients underwent surgery. Seven patients, those who had no neurological deficits pre-op, remained unchanged post-op. Amongst the 46 patients who had preoperative neurological deficits, eight had neurological deterioration post-op; five had deterioration in motor power and three had urinary problem. Five of these patients had type Id split, 2 had type Ic split, and one had type Ib split. However, among 8 patients who deteriorated post-op, four improved to preoperative status by the time of discharge. Thus, 4/53(7%) patients had long-term deficits, all with type Id split. Follow-up data was available for 36 patients (68%) and mean follow-up period was 12 months (range 6-24 months). Follow-up MRI revealed decrease in syringomyelic cavity in 6 of the 14 patients (44%) who had syringomyelia on preoperative MRI scans.

Conclusion:

Overall, SCM is an uncommon condition. In all cases of progressive scoliosis, MRI must be carried out. We subjected all asymptomatic patients to surgery and none developed post-op deterioration. Overall post-op neurological deterioration was noticed in 15% patients, of which 8% had transient post-operative deterioration. The new Type I SCM subclassification system proposed by Mahapatra and Gupta is found to have a significant prognostic value in assessing post-operative neurological deterioration in patients with type I SCM.

Mixed split cord malformation: are we missing something?

BACKGROUND

The new classification for split cord malformation, based on the unified theory of embryogenesis includes two types Type I and II defined on the basis of the nature of the medium septum and the state of the dural tube. According to this, these are the only two essential features needed for typing and there is never an overlap between the two main forms. We have described two cases that defy this theory.

CASE REPORT

We present two patients with split cord malformation who appear to have a combination of features specific to Type I and Type II. Both patients had a partial bony spur within a single dural sac.

CONCLUSION

An overlap between the two forms of split cord malformation does exist. The role of meninx primitiva in the formation of median bony septum is debatable.

An unusual case of spinal dysraphism with four splits including three posterior spurs

BACKGROUND

Composite-type split spinal cord malformation (SCM) is very rare and results from 2 separate foci of ectoendodermal adhesions and endomesenchymal tracts leading to the development of SCM with an intervening normal cord in the same patient. Posterior spurs are even rarer. We report a unique case of composite SCM, where the patient had 3 posterior bony spurs and 1 fibrous spur at different levels. To our knowledge, this is the first reported case of a patient having composite-type SCM with posterior spurs at 3 different levels.

CLINICAL PRESENTATION

A 3-year-old girl presented to us with progressively worsening scoliosis. Neurological examination was unremarkable except for mild weakness in the left lower limb. Three-dimensional CT imaging demonstrated posterior bony spurs located at T(6), T(12) and L(3) levels. The patient underwent T(11)-L(5) laminoplasty and T(5)/T(6) laminectomy and excision of SCM type 1 with division of the thickened filum terminale. All the bony spurs arose from the inner surface of the lamina, where the base of the spur was located.

CONCLUSIONS

The unique point of this case report is the rarity of such a presentation. Careful planning and knowledge of the occurrence of such conditions can make surgery in these children safe, and all the levels can be treated in a single setting.

Complex split cord malformation with mediastinal extension of a teratoma and simultaneous ventral and dorsal bony spur splitting the cord

INTRODUCTION

Association of split cord malformation with teratoma is an extremely rare condition. It is very unusual to find split cord malformation with teratomas extending into the posterior mediastinum and still rarer to find bony spur arising dorsally and ventrally at the same level.

CASE REPORT

The authors describe the case of a 2-year-old child who presented with dorsal kyphosis and a dermal sinus. The neurological examination was unremarkable. MRI and noncontrast CT of the spine revealed Pang's type I split cord malformation at the D9-12 level. Bony spur was seen arising both dorsally and ventrally at the D9-12 level. Intraoperatively, intradural teratoma was found coming extradurally both posteriorly between the 2 spurs and anteriorly into the posterior mediastinum above the bony spurs through a defect in the vertebral body of 2 cm diameter. Near total excision was performed.

DISCUSSION

To the best of the authors' knowledge, this is the second case report of an intradural teratoma extending into the mediastinum, occurring with split cord malformations and other spinal anomalies. A similar case was reported from our institute in 2006. This is the first report of its kind of simultaneous dorsal and ventral bony spur at the same level.

Unusual split cord with neurenteric cyst and cerebellar heterotopia over spinal cord

OBJECTIVE

To report a case of splitting of a cord, which could neither be classified as type I nor type II according to Pang's classification. The child had associated neurenteric cyst and cerebellar tissue heterotopia.

CASE REPORT

A 3-year-old girl presented with a tuft of hair and dermal sinus at her upper dorsal spine. She had splitting of cord into two halves by two intradural horny osseocartilaginous spurs leaving a gap of 3 mm in between (two spurs and two halves of cords). A neurenteric cyst was seen passing from the anterior to posterior aspect of the cords through this gap. An associated heterotopic cerebellar tissue mass was encountered over the dorsum of cord proximal to splitting. The dermal sinus, neurenteric cyst, and spurs were excised to detether the cord. The heterotopic tissue was biopsied. The child had no neurological deficit at 2.5 years follow-up.

CONCLUSION

An unusual splitting of cord by unusual spurs may leave a gap between two spurs and two halves of cords to pass a neurenteric cyst. Rarely, heterotopic tissue may be associated with split cord syndrome. A dermal sinus may lead into underlying neurenteric cyst (rather than dermoid).

An unusual type of split cord malformation

A 4-year-old girl with an unusual type of split cord malformation (SCM) is reported. She presented with a capillary hemangioma in the lumbosacral region. Computed tomography and magnetic resonance imaging studies of the whole spinal axis revealed SCM. There was a Type II SCM at the L1 level and a dorsal bony septum at the S2 level. The conus medullaris terminated at the upper end of the L2 vertebral body. There was no tethered cord syndrome. There is no reported case to date of SCM with this malformation. She did not undergo surgical treatment due to the absence of tethered cord syndrome. Her neurological examination was unremarkable and she is still being followed up without any neurological abnormalities.

Split cord malformations: an experience of 203 cases

METHODS

A total of 203 patients with split cord malformation (SCM) were operated on at our centre between March 1989 and October 2003. Patients' demographic profile, radiological and operative details, complications and surgical outcome were evaluated retrospectively.

RESULTS

The mean age of the patients was 7.4 years and the female to male ratio was 1.3:1. The dorsolumbar and lumbar regions were the most common sites. One hundred thirty-two patients had type I SCM and 71 had type II SCM. One or more skin stigmata were present in 60% cases, hypertrichosis being the most common. Asymmetric weakness of the lower limbs and sphincter disturbances were present in 73 and 33% cases, respectively. Twenty-seven patients were asymptomatic. Of the symptomatic cases, 40.5% showed improvement in motor power, whereas 31% regained continence. The neurological status was unchanged in 48%. Seven percent of the patients showed neurological deterioration immediately after surgery.

CONCLUSIONS

SCMs are rare malformations of the spinal cord. We present the largest series so far reported in the world literature. The risk of developing neurological deficits increases with age; hence, all patients with SCM should be surgically treated prophylactically even if asymptomatic.

The intermediate type split cord malformation: hypothesis and case report

METHODS

A patient is described in which a complete osteofibrotic dorsally implanted septum was found in combination with a split cord malformation in a single dural tube. This case cannot be explained using the widely used theory as proposed by Pang et al. [Pang D, Dias MS, Ahab-Barmada M (1992) Split cord malformation, part I: A unified theory of embryogenesis for double spinal cord malformations. Neurosurgery 31:451-480] but must be regarded as a combination of type I and II split cord malformation.

RESULTS

The authors state that all types of split cord malformation can be reduced to a single derailment during development, with various degrees of severity.

CONCLUSIONS

The configuration of the malformation is determined by the way the median parts of the mesoderm come to development. Type I and II split cord malformation are not distinct entities.

Split spinal cord malformations: report of 22 cases and review of the literature

OBJECT

The aims of this study were to describe the embryological changes that drive the formation of a split spinal cord malformation, analyse the forms of presentation, evaluate the diagnostic procedures and discuss the indications for the different forms of therapy for each case.

METHODS

Clinical and radiological features of 22 cases of split spinal cord malformations (SSCM) are reported. Three groups of patients are considered: group a, patients with signs of tethered cord or scoliosis; group b, patients with midline cutaneous stigmata and group c, patients with a meningocele or meningomyelocele.

CONCLUSION

While CT scan is particularly useful for the evaluation of vertebral bodies and posterior arch abnormalities and spur characteristics in SSCM, MRI gives complementary information on the anatomy of spinal cord, dural sac, conus and filum terminale and permits the exclusion of associated lesions such as hydro-syringomyelia, dermal sinus or dermoid and epidermoid cysts. Surgery should be considered indicated in all cases of SSCM, even the asymptomatic ones, except in very badly handicapped meningomyelocele patients with nonprogressive disability and type II SSCM.