INTRODUCTION: The most common reason for a poor surgical result of lumbar spinal stenosis is failure to recognize lateral spinal stenosis. It is entirely possible that the lumbar spinal nerve can be compressed at two or more sites from the intra‐spinal canal to the extraforaminal zone. The aim of this study is to introduce the doublecrush syndrome of the 5th lumbar spinal nerve (LSN) as a cause of failed back surgery (FBS).
METHODS: The authors retrospectively surveyed 18 surgical failure cases of the 5th lumbar radiculopathy. All of them had undergone the laminectomy at L4‐5 alone for double lesions of 5th LSN without recognition of extraforaminal stenosis at L5‐S1. The effects of the primary operations were somewhat effective, but not satisfactory for these patients. Therefore, additional extraforaminal decompression was undertaken for the salvage. The changes of leg pain and walking capacity were examined according to the JOA score during the follow‐up period to understand clinical features of this type of FBS.
RESULTS: The average leg pain and walking capacity scores (full score: 3 points) improved immediately after primary operation from 1.06 and 0.67 to 2.00 and 1.87. However, sciatica and intermittent claudication were not completely resolved and deteriorated with time. Before the salvage, the leg pain and walking capacity scores went down to 0.87 and 0.87. After the salvage, those improved to 2.1 and 2.5 again, and lasted up to final follow‐up. Additional surgery allowed the patients satisfactory relief of pain and disability.
DISCUSSION: This fact suggests that double‐crush syndrome may exist in surgical cases of lumbar spine in the same way as the nerve entrapment syndrome in the upper extremity. In order to improve surgical outcome, this disease condition must always be taken into account. The treatment should be applied to all the compression sites along the course of the 5th LSN from the intra‐spinal canal to the extraforaminal zone.