High-resolution sonography of the common peroneal nerve: detection of intraneural ganglia.

We performed sonographic examination of the common peroneal nerve in 41 consecutive patients with a footdrop to determine whether there was a structural lesion of the peroneal nerve. Five of the 28 patients (18%) with an isolated peroneal mononeuropathy had an intraneural ganglion of the peroneal nerve confirmed by histology. High-resolution sonography should be considered in patients with nontraumatic peroneal palsy.