The radiology of thoracic disc protrusion.

The radiological features of 20 surgically proven thoracic disc protrusions are reviewed. In 15 (75%), characteristic plain film changes were found to be very helpful in making the correct diagnosis. Calcified disc material in the spinal canal was clearly demonstrated in 11 (55%) cases, and this, in association with linear calcification in the adjacent disc space, has been shown to be diagnostic of the condition. At myelography, central protrusions (55%) were found to be predominant, while lateral protrusions were uncommon. The differential diagnosis of a calcified lesion in the spinal canal includes thoracic disc protrusion, osteochondroma and meningioma.