Computerized tomography in diagnosis of compression of the common peroneal nerve by ganglion cysts.

A 48-yr old man noted gradual onset of pain, and paresthesia on the lateral aspect of his right leg. The findings were suggestive of S1 root compression. CT of spine was normal. Physical examination revealed a small mass overlying the right fibular head. CT revealed this to be a cystic mass. At surgery a ganglion cyst compressing the common peroneal nerve was found. Peripheral nerves may be compressed by ganglia producing a syndrome mimicking central nerve root compression. CT is the modality of choice for detection of these lesions.