[Re-operation in protrusion of a lumbar intervertebral disk: report of 30 cases].

Thirty cases, who had been operated on under diagnosis of protrusion of lumbar intervertebral disk, were re-operated upon because of failure of relieving their sufferings or tardy recurrence of symptoms. The actual causes found at operation were: missing a preexisting schwannoma in 4 patients, failing in working on correct space in diskectomy in 3, leaving another co-existed protruded disk untouched in 2, and lastly, recurrence of disk protrusion at the previous space in 7. Causes of these mishaps were discussed and some preventive precautions and measures have been suggested.