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. Summa
ry of Background Data. A 34-year-old woman presented with spastic para
paresis. Magnetic resonance imaging scan of the thoracic spine reveale
d anterior displacement and tethering of the cored at T6-T7 and a dors
al intradural arachnoid cyst. Excision of the cyst was performed witho
ut improvement in symptomatology. During reoperation the thoracic spin
al cord hernia was discovered and was reduced intradurally. Methods. T
he authors describe the clinical, radiographic, and surgical findings
of this patient and review the findings from other reported cases. The
y discuss the proposed theories for the pathophysiology of the cord he
rniation and the surgical management. Results. The patient had idiopat
hic thoracic spinal cord herniation as there was no history of previou
s 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 def
ect. Conclusion. Idiopathic spinal cord herniation should be recognize
d as a cause of progressive myelopathy that can be managed successfull
y with microsurgical techniques.