DISCAL HERNIATION, AN EXCEPTIONAL REASON FOR REOPERATION AFTER LUMBAR STENOSIS SURGERY

Purpose of the study: Discal herniation is an exceptional cause of lumbar canal stenosis. When surgery for this disorder was first performed in the sixties, discectomy was not exceptional because discal protrusions were frequent. It was rather rapidly observed however that these protrusions were actually osteoarthitic discal rims that do not cause root compression. Discectomy was thus almost completely abandoned for lumbar stenosis surgery. Consequently, the development of true discal herniation after surgery for lumbar canal stenosis is highly exceptional. To our knowledge, this situation has not been reported in the literature. Among several hundred procedures for decompression of the lumbar canal practised in our unit over the last thirty years, we have observed seven cases. Material and methods: The patients were aged 43 to 74 years at the time of reoperation (mean 61 years). The stenosis was at the L4-L5 level in all patients and extended to L3-L4 in three and to L5-S1 in two and was bilateral in one patient. The L4-L5 disk had been removed at the prior surgery in three patients. Delay to recurrent pain was variable, from six months to eleven years. The sciatic pain was associated with motor disorders in one patient. Discal herniation was observed at the L4-L5 level in all patients and was often voluminous, excluded in three patients. Reossification was present in one patient but did not have a compressive effect. Treatment after recurrence was chemonucleolysis in three patients, with two successes and one failure. Surgical treatment by discal excision was used in four cases associated with instrumented fusion in one patient. Results: The patients were reviewed at one to ten years after the second operation. Nucleolysis was successful in two and a failure in one. The patient with failure of nucleolysis was treated by a new decompression with fusion and achieved an excellent result at ten years. Pain relief was achieved after surgery in all patients though only partial in one. Discussion and conclusion: Discal herniation is rare in elderly subjects and can cause problems late after surgical decompression of lumbar canal stenosis. It is important to search for discal herniation which is not always easy to confirm radiologically due to postoperative remodeling. Chemonucleolysis is an effective and economical solution when the disk has not been resected during the first procedure. When an operation is necessary, spinal fusion is not useful except in case of associated instability.