Split cord malformations: A two years experience at AIIMS

Abstract

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.

Keywords: Spinal dysraphism; split cord malformation; unified theory.

Figure 1

(a-d) Sagittal, axial T1W, axial T2W MRI images and axial CT image of a representative case showing SCM type I with classic bony spur at L1 vertebral level causing asymmetric division of spinal cord into two separate hemicords with separate dural sheaths

Figure 2

(a-d) Sagittal, axial T1W, axial T2W MRI images and axial CT image of a representative case showing SCM type I with dorsally located bony spur at D12 vertebral level. Also note low lying cord and long segment syrinx