What is the treatment for Diastometamyelia (split spinal cord syndrome)?

Treatment for Diastematomyelia (Split Spinal Cord Malformation)

Surgical excision of the bony or fibrous septum is the definitive treatment for Type I diastematomyelia with progressive neurological deterioration or tethered cord, while conservative observation is recommended for asymptomatic Type I and all Type II diastematomyelia. 1

Understanding the Two Types

Split cord malformation exists in two distinct forms that require different management approaches:

• Type I diastematomyelia contains two hemicords, each within separate dural sacs, with an intervening extradural bony or cartilaginous spike that causes tethering 2
• Type II diastematomyelia (diplomyelia) contains two hemicords within a single dural sac with a fibrous band, typically less symptomatic 2
• Type I accounts for approximately 79% of cases (123/156 patients) and Type II represents 21% (33/156 patients) 1

Surgical Indications Algorithm

Operate immediately for:

• Type I diastematomyelia with progressive neurological deterioration - surgical removal of the bony spur prevents further damage and improves symptoms in 78% of patients (96/123 cases) 1
• Type I with tethered filum terminale - intradural exploration and release of tethering prevents irreversible spinal cord damage 1
• Before planned spinal deformity correction surgery - removal of the spur prevents neurological injury during corrective procedures for associated scoliosis (present in 60% of cases) 3

Observe conservatively for:

• Asymptomatic Type I diastematomyelia - these patients show stable neurological status without surgery over 2-20 year follow-up 1
• All Type II diastematomyelia - surgical intervention provides no functional improvement, with 9 surgical patients remaining stable without improvement and 24 nonsurgical patients maintaining stable deficits 1
• Stable, non-progressing neural deficits - observation is safer than prophylactic surgery, which carries risk of significant neurological damage 4, 3

Critical Surgical Considerations

The operation involves:

• Laminectomy with excision of the bony, cartilaginous, or fibrous septum dividing the hemicords 1
• Intradural exploration of the lumbar region to release conus tethering when present 1
• Most lesions occur in the lumbar and thoracolumbar region, typically spanning 6 vertebral segments 1

Expected surgical complications include:

• Cerebrospinal fluid leakage (1.3% of cases, 2/154 patients) 1
• Temporary neurological deterioration (2.6% of cases, 4/154 patients) 1
• Epidural hematoma (0.6% of cases, 1/154 patients) 1

Common Pitfalls to Avoid

Never perform prophylactic removal of bone spurs in asymptomatic patients - two children suffered significant neurological damage during prophylactic spur removal, demonstrating that the surgical risk outweighs benefit without progressive symptoms 4

Do not assume all diastematomyelia requires surgery - Type II diastematomyelia shows no improvement with surgical intervention, making conservative management the appropriate choice 1

Avoid spinal traction or corrective surgery without first removing the spur in Type I - three children underwent successful spinal correction under traction with spurs in situ without sequelae, but this carries substantial risk and pre-operative spur removal is safer when corrective surgery is planned 4, 3

Recognize associated cutaneous markers - hairy patches (fawn's tail), capillary malformations, dermal sinus tracts, or subcutaneous masses overlying the spine should prompt imaging evaluation 2

Image before any spinal procedure - myelography or MRI is essential before any procedure that might cause traction on the spinal cord, as 87% of patients have neural deficits and 60% have congenital scoliosis 3

Long-Term Outcomes

Surgical patients with Type I diastematomyelia maintain stable neurological status without symptom aggravation over 2-20 years (mean 4.5 years) of follow-up, with 78% showing clinical improvement 1. Conservative management of appropriate cases (asymptomatic Type I and all Type II) results in stable neurological manifestation without deterioration over the same follow-up period 1.