Localizing peroneal nerve lesions.

The main result of a peroneal nerve lesion, foot drop, is so obvious that few patients can ignore its presence. However, the detailed knowledge of peroneal nerve anatomy needed to localize the lesion may tax even a seasoned clinician. Examination of the strength of five muscles--the tibialis anterior, peroneus longus and brevis, posterior tibial, gluteus medius and quadriceps--provides information necessary to localize the site of the neuropathy. This tentative localization can be confirmed by electromyography. Treatment is directed to the cause of the lesion and stabilization of the ankle if necessary.