Utilizing peroneal nerve conduction studies to differentiate L5 radiculopathy and peripheral neuropathies of the...

L5 radiculopathy, peroneal neuropathy at the fibular head (PNFH), and sciatic neuropathy (SN) often share similar clinical features, such as foot drop. The ability of peroneal nerve conduction studies (NCSs) to distinguish these three conditions was investigated.

NCS findings of the patients with L5 radiculopathy, PNFH and SN were reviewed retrospectively. Additionally, needle electromyography (EMG) findings of the tibialis anterior (TA) and peroneus longus (PL) muscles were analyzed.

Sixty-six patients with L5 radiculopathy, 53 patients with PNFH, and 75 patients with SN were included. Fourteen (21.2%) patients with L5 radiculopathy, 14 (26.4%) patients with PNFH, and 57 (76.0%) patients with SN had abnormal superficial peroneal nerve compound nerve action potential (CNAP) amplitude. Superficial peroneal nerve CNAP amplitude abnormalities were significantly more prevalent in SN patients (p < 0.001). Among patients with abnormal superficial peroneal nerve CNAP amplitudes, peroneal nerve compound muscle action potential (CMAP) abnormalities recorded from TA/extensor digitorum brevis were observed in 11/9 L5 radiculopathy patients (p = 0.014/0.002), 6/6 PNFH patients (p = 0.413/0.063), and 48/37 SN patients (p < 0.001/0.001). Needle EMG abnormalities in TA/PL muscles were found in 50(75.8%)/61(92.4%), 53(100%)/34(64.2%), and 51(68.0%)/45(60.0%) of patients with L5 radiculopathy, PNFH, and SN, respectively.

This study highlights that, unlike PNFH, superficial peroneal nerve CNAP amplitude abnormalities in L5 radiculopathy and SN are often accompanied by peroneal nerve CMAP amplitude abnormalities.