Spontaneous thoracic spinal cord herniation through an anterior dural defect.

A 44-year-old woman was examined for progressive left lower extremity weakness and spasticity. Thoracic spine MR imaging and CT myelography showed a ventral dural defect at T7-T8 with an extradural subarachnoid fluid collection and extradural herniation of the spinal cord. Intraoperative sonography confirmed the appropriate level for dural entry and the finding of spinal cord herniation. After reduction of the herniated spinal cord, the patient experienced gradual improvement in neurologic function.