Surgical treatment of post-traumatic myelopathy associated with syringomyelia.

STUDY DESIGN Retrospective review. OBJECTIVE Evaluate the clinical outcome of surgical intervention for post-traumatic syringomyelia. INTRODUCTION Progressive post-traumatic cystic myelopathy (PPCM), or syringomyelia, can occur after spinal cord injury. The authors present their surgical treatment protocol and treatment outcome of a series of patients with post-traumatic syringomyelia. METHODS The medical records of 53 patients with PPCM undergoing surgical treatment were reviewed. Laminectomies and intraoperative ultrasonography were performed. For patients with no focal tethering and only a confluent cyst on ultrasonography, a syringosubarachnoid shunt (stent) was inserted. For patients with both tethering and a confluent cord cyst, an untethering procedure was performed first. When a cyst showed significant size reduction (>50%) after untethering, no shunt was placed. When the cyst size persisted on ultrasonographic images, a short syringosubarachnoid shunt was used. The mean follow-up was 23.9 months for the 45 patients available for follow-up (range 12-102 months). RESULTS The interval between the causative event and the operation was from 5 months to 37 years (mean 6.5 years). Pain was the most frequent manifestation, followed by motor deterioration and spasticity. Postoperative improvements in >50% of the patients were noted in those presenting with worsening motor function or spasticity. In 19 of 28 patients with associated tethered spinal cord, untethering alone caused significant collapse of the cyst. Postoperative MRI demonstrated cyst collapse in 95% of the patients with untethering alone and 93% of the patients with a syringosubarachnoid shunt. CONCLUSION Post-traumatic syringomyelia can occur with or without cord tethering. Untethering alone for patients with cord tethering and cyst formation can reduce cyst size and alleviate the symptoms and signs of syringomyelia in the majority of these cases. Untethering with expansion of subarachnoid space with an expansile duraplasty may be a more physiologic way of treating a tethered cord with associated syringomyelia, i.e., treating the cause rather than the result.