An Amendment to the Neidre and MacNab Classification System for Lumbosacral Nerve Root Anomaly and Its Implication in...

Lumbar disc herniation complicated with nerve root anomaly presents great challenges to diagnosis and treatment. Improper selection of surgical procedures may cause inferior outcomes and neurologic injury.

A 66-year old man presented with low back pain and radicular symptoms involving bilateral L5 and S1 nerve roots. Instead of percutaneous endoscopic lumbar discectomy, aggressive decompression was carried out because of a deviation between the examination and imaging findings. Surgical detection disclosed a confluent nerve root comprising 2 adjacent contributions that arose from the thecal sac exiting from the left L5/S1 foramen, in the absence of the root otherwise exiting through the caudal foramen. We found that the overwhelming left radicular symptoms were attributable to compression on this swelling anomalous root by a narrowed L5/S1 root cannula. Aggressive decompression and distraction of the intervertebral space successfully released the nerve root. Twenty months postoperatively, the patient experienced evident relief of the radicular symptoms and improvement of muscle strength with no complication.

Lumbosacral nerve root anomaly should be remembered and ruled out before selecting surgical methods. Inappropriate procedures can not alleviate the symptoms associated with the anomalous roots and may expose such patients to the risk of neural injury. In clinical practice, surgeons should select percutaneous endoscopic lumbar discectomy with caution, and stop the procedure instantly when unexplainable radicular irritation is evoked.