27 - Tarsal Tunnel Syndrome

Abstract

Patients with pain and numbness in the foot often are referred to the electromyography (EMG) laboratory for evaluation of possible tarsal tunnel syndrome (TTS). TTS results from entrapment of the distal tibial nerve under the flexor retinaculum at the medial ankle. Superficially, it might seem that tibial nerve entrapment under the flexor retinaculum at the ankle is analogous to median nerve entrapment under the flexor retinaculum at the wrist (i.e., carpal tunnel syndrome [CTS]). However, in contrast to CTS, which is very common, TTS is exceptionally rare. Although electrophysiology can be useful in demonstrating focal slowing at the tarsal tunnel in those rare cases of true TTS, every electromyographer should be aware that significant technical difficulties are often encountered when studying the distal tibial nerve and the muscles it innervates, especially in older patients. Neuromuscular ultrasound can be very helpful in cases of suspected tibial neuropathy at the tarsal tunnel, especially in cases of trauma or unusual structural lesions.