High-resolution ultrasound as a diagnostic adjunct in common peroneal neuropathy.

E ntrapment neuropathy of the common peroneal nerve is caused mostly by compression at the fibula head region. In cases of severe axon loss, demonstration of conduction block or reduction of conduction velocity would be difficult. Apart from demyelination, mechanical factors and ischemic mechanisms may play a role. Differing degrees of damage to individual nerve fascicles may occur within the common peroneal nerve, rendering interpretation of needle electromyography (EMG) difficult. High sciatic nerve lesions are also known to mimic peroneal neuropathy at the fibular head if electrodiagnostic examination is not performed adequately. High-resolution ultrasonography (US) may be a potential diagnostic tool in these technically challenging circumstances.