[A case of idiopathic thoracic spinal cord herniation].

We report a case of idiopathic thoracic spinal cord herniation. A 63-year-old female came to our hospital complaining of a slowly progressive gait disturbance that began 5 years ago. She showed signs of a left dominant spastic paraparesis and sensory disturbance. Her left foot had already became a drop foot from 2 years ago. Magnetic resonance (MR) imaging and computed tomographic (CT) myelography demonstrated that the atrophic spinal cord had displaced to the ventral side with a dilated dorsal subarachnoid space at T2-3 level. Surgery was performed via T2-3 laminoplastic laminectomy. The ventral aspect of the spinal cord revealed a defect in the inner layer of the duplicated dura mater, into which the gliotic spinal cord herniated. The herniated spinal cord was repositioned and the dural defect was repaired using a GORE-TEX dura substitute. Postoperative course was uneventful. Although the patient showed marked improvement in the right lower limb, there was slight improvement in the left lower limb. The clinical symptoms of this disease are uncommon and progress slowly, and if left untreated will result in paraparesis. Therefore early diagnosis and operation is important to prevent the progression of symptoms and to achieve a satisfactory outcome.