Double Crush Syndrome in the Lower Extremity: Simultaneous L5 Radiculopathy and Common Peroneal Nerve Compression

Background: Double crush syndrome (DCS) is defined as multiple sites of compression along a single nerve. The combination of a compressive proximal lesion in the lumbar spine and a distal common peroneal nerve entrapment may result in compound nerve dysfunction.

Methods: A retrospective analysis of 100 patients who underwent common peroneal nerve decompression with a diagnosis of L5 radiculopathy between January 2000 and April 2023 at two quaternary academic institutions was performed. Patients were included if they had both active L5 radiculopathy and active peroneal mononeuropathy on electromyography (EMG) or imaging findings. Ten patients had a "pure" DCS of the lower extremity, meaning the co-occurrence of both active diseases based on EMG or imaging. Descriptive statistics of patient demographics, clinical presentation, surgical details, and outcomes were performed.

Results: All 10 patients underwent common peroneal nerve decompression, 3 of the patients underwent a prior lumbar spine surgery to address their L5 radiculopathy. Preoperatively, 6 patients (60%) had a positive Tinel's sign, which reduced to 3 patients (30%) postoperatively. Relative to preoperative strength, dorsiflexion, extensor hallucis longus, and ankle eversion strength all improved on average following common peroneal nerve decompression. The presence of numbness in the lateral leg or dorsal foot decreased from 9 (90%) preoperatively to 4 (40%) postoperatively.

Conclusions: This is the first series to report DCS with two active points of compression in the lumbar spine and lower extremity based on EMG and imaging findings. Common peroneal nerve decompression was found to improve average dorsiflexion strength.