Anterior tarsal tunnel syndrome.

Anterior tarsal tunnel syndrome is a rarely reported entrapment neuropathy of the deep peroneal nerve under the extensor retinaculum at the ankle. The roof of the tunnel is the inferior extensor retinaculum. The floor is the fascia overlying the talus and navicular. Within the tunnel are four tendons, an artery, a vein, and the deep peroneal nerve. Two patients with foot pain and dysesthesias had prolonged peroneal distal latencies with reduced amplitudes from the extensor digitorum brevis (EDB). Electromyographic (EMG) abnormalities were confined to the EDB. Both patients underwent surgical decompression of the anterior tarsal tunnel with reduction of their pain and dysesthesias. If present, an accessory peroneal nerve, which does not go through the tunnel, can mask EMG findings in the EDB. Diagnosing anterior tarsal tunnel syndrome can also be difficult if there is a tendency to assume that fibrillation potentials in the EDB are due to shoe wear and prolonged peroneal latencies to cool extremities.