Anomalies of the lumbosacral nerve roots. Review of 16 cases and classification.

Sixteen cases of lumbar nerve root anomalies found at surgery are reviewed and a classification system presented. All but two patients had an associated disc herniation which initiated the symptomalogy and was the indication for surgery. Fifty percent were found at repeat exploration. Eleven patients had conjoined nerve roots, five had two roots in one foramen, and three had connecting roots. Nerve root anomalies should be suspected in cases of failed disc surgery. Adequate decompression by foraminotomy or excision of pedicles is required as well as discectomy to alleviate the symptomatology.