Idiopathic spinal cord herniation associated with calcified thoracic disc extrusion--case report.

A 48-year-old man presented with idiopathic spinal cord herniation associated with calcified thoracic disc extrusion at the T7-8 intervertebral level, manifesting as Brown-Sequard syndrome at the thoracic level persisting for 20 years. Preoperative magnetic resonance imaging and computed tomography myelography revealed ventral displacement of the spinal cord and extrusion of a calcified disc at the T7-8 intervertebral level. At surgery, the spinal cord herniation at this level was released from the dura mater and carefully returned to the dural sac. An extruded calcified thoracic disc was found just below the dural defect at the same level. The development of idiopathic spinal cord herniation is associated closely with a defect in the ventral dura mater of unknown etiology. In our case, the etiology of the ventral dural defect was probably associated with the calcified thoracic disc extrusion.