Spontaneous thoracic spinal cord herniation. A case report

STUDY DESIGN: This is a case report. OBJECTIVE: To focus attention on spontaneous spinal cord herniation as a rare cause of myelopathy that can be diagnosed preoperatively and can be corrected surgically. SUMMARY OF BACKGROUND DATA: A 34-year-old woman presented with spastic paraparesis. Magnetic resonance imaging scan of the thoracic spine revealed anterior displacement and tethering of the cord at T6-T7 and a dorsal intradural arachnoid cyst. Excision of the cyst was performed without improvement in symptomatology. During reoperation the thoracic spinal cord hernia was discovered and was reduced intradurally. METHODS: The authors describe the clinical, radiographic, and surgical findings of this patient and review the findings from other reported cases. They discuss the proposed theories for the pathophysiology of the cord herniation and the surgical management. RESULTS: The patient had idiopathic thoracic spinal cord herniation as there was no history of previous spine surgery or injury. The authors believe that the cord herniated through a congenital dural defect, which resulted in the development of a pseudoarachnoid cyst dorsally to the hernia. The patient improved after intradural reduction of the hernia and closure of the dural defect. CONCLUSION: Idiopathic spinal cord herniation should be recognized as a cause of progressive myelopathy that can be managed successfully with microsurgical techniques.