Abnormal arrangement of the lower lumbar and first sacral nerves within the spinal canal.

Case 1-A man aged 46 stated that five months ago he had strained his back at work lifting bags of cement. The pain was felt low on the left side, and later radiated down the left leg. He was unable to work for six weeks. The pain did not resolve completely and had recently become worse again, extending to the left foot. He walked with a forward stoop, favouring the left leg. All back movements, particularly flexion, were limited. Local tenderness was not marked but straight leg raising was markedly restricted. The left knee jerk was slightly diminished and the left ankle jerk was absent. There were sensory changes, mainly hyperaesthesia, over the lower part of the leg. Disc hernia probably affecting the fifth lumbar nerve root was suspected. At operation a disc hernia was found and removed, but it was noted that the fifth lumbar and first sacral nerves appeared to arise from the same nerve root and to separate extrathecally. The disc hernia bulged posteriorly beneath both nerves at their conjoined point of emergence from the theca (Fig. 1). Progress was slow but nine months after the operation the patient was passed fit for restricted employment. ln reply to a recent follow-up enquiry he wrote that he was “fighting fit” at 60 and doing a full day’s work, fourteen