Intraneural ganglionic cyst of the common peroneal nerve: case report and review of the literature.

The authors report a case of compression of the peroneal nerve by an intraneural ganglionic cyst. The chief complaint is generally a lateral upper leg pain occasionally associated with foot drop and swelling of the upper tibiofibular joint. In our case, the disease was revealed by a tentative intraarticular injection of betamethasone. Early microsurgical treatment remains the only way to avoid permanent motor sequellae.