Compression neuropathy of the peroneal nerve secondary to a ganglion cyst.

Peripheral neuropathies caused by ganglion cysts are rare, particularly in the lower extremities. The case of a 45-year-old man with a two-month history of foot drop and swelling in the region of the right fibular head is presented. Physical examination and electromyogram studies verified a peroneal nerve palsy. Magnetic resonance imaging revealed a lobulated, multilocular, cystic-appearing mass extending around the fibular neck. Surgical decompression of the nerve with removal of the mass and careful articular branch ligation was performed. Surgical pathology reports confirmed the diagnosis of a ganglion cyst. The patient regained full function within four months of the decompression. Pertinent findings on physical examination are discussed, as well as electromyogram and magnetic resonance imaging results. If symptoms persist, early surgical decompression (between the third and fourth months) is recommended.