Repetitive Plantar Flexion (Provocation) Test for the Diagnosis of Intermittent Claudication due to Peroneal Nerve Entrapment Neuropathy: Case Report

The diagnosis of peroneal nerve (PN) entrapment neuropathy (PNEN) is based on clinical symptoms and nerve conduction studies. However, these studies do not always detect PNEN. Our 64-year-old patient suffered persistent left L5 numbness after two lumbar surgeries. Two years before admission to our institute his left leg pain gradually reappeared. When walking, his numbness in the left lower thigh to the dorsum of the foot increased. Electrophysiological testing revealed no conduction block on the PN. To identify the origin of his intermittent symptoms we performed loading of repetitive ankle plantar flexion in the at-rest posture to avoid the lumbar factor. We used this provocation test to check for PNEN because it occurs at a site where the PN passes the soleus- and the peroneus longus muscle (SM, PLM). The symptoms appeared reproducibly within 10 s of loading. PN neurolysis under local anesthesia showed that the PN was strongly compressed by the SM and PLM. This procedure eased his symptoms and he was able to walk without elicitation of numbness and pain upon repetitive ankle plantar flexion. In our case, repetitive plantar flexion elicited the symptoms and this provocation test may be useful to identify PN dynamic entrapment neuropathy as the origin of intermittent claudication.