Preoperative diagnosis of conjoined roots anomaly with herniated lumbar disks.

Twelve cases of nerve root anomalies encountered during investigation for low back pain and sciatica are presented. Most of these patients had a herniated lumbar intervertebral disk and were operated upon with the preoperative knowledge of an associate nerve root malformation. Three patients were found to have a symptomatic nerve root malformation without disk herniation. These patients were conservatively treated. In all cases we found a constant myelographic sign that is described.