Herniated thoracic disks.

Thoracic disc herniation is uncommon. An incidence of 0.25 to 0.75 per cent of protruded disks are in the thoracic region. A peak incidence is noted in the fourth decade with 75 per cent of the protruded disks occurring below T8. Pain is the most common initial symptom, present in 57 per cent of the cases, followed by sensory disturbances and motor involvement. By the time of diagnosis, 90 per cent of the patients have signs of spinal-cord compression. Although myelography has been considered the test of choice, 8 per cent false negative results and a correct preoperative diagnosis of 56 per cent has been reported. Now, with CT scanning with and without metrizamide, more accurate diagnoses can be achieved, even with cases in which myelography is negative. There has been a considerable improvement in the surgical treatment of herniated thoracic disks with over an 80 per cent rate of success for surgical approaches other than the posterior approach (decompressive laminectomy). An early and accurate diagnosis, coupled with improvement in the surgical approach, offers a much better prognosis for patients with thoracic disk herniation.