[Intervertebral disk prolapse as an unusual cause of Horner's syndrome].

A case of protrusion of the first thoracic intervertebral disc is presented. The patient suffered from severe acute pain in the chest and left arm. Horner's syndrome was present, probably due to compression of the preganglionic sympathetic fibres as they leave the spinal cord through the anterior root. The diagnosis was confirmed by myelography and CT scanning. The prolapsed disc was removed by laminectomy and the symptoms resolved.