[Sciatica and nerve root anomalies. Apropos of a series of 20 cases].

We present 20 operative cases of lumbar nerve root anomalies, divided into 6 anatomical types: nerve roots with common dural emergence (4 cases), contiguous dural emergence (6 cases), with common dural sheath (4 cases), splited nerve roots (2 cases), anastomosis between roots (3 cases) and plexiform nerve roots (1 case). 14 cases are associated with a discal hernia. 10 cases presented with unilateral but biradicular sciatica. The asymmetry of emergence is the best symptom of the pre-operative radiological evaluation on the CT scan, moreover on the myelography. The management led to an enlargement of the surgical field by hemilaminectomy to recognize the anomaly and make easier the discectomy. In 3 cases, the anomaly was recognized in patients who had been previously operated on. There are only 53% of satisfactory final results. We present a review of the main publications concerning this subject.