A 48 year old man presents with pain and discomfort over the dorsum of the left foot and the front of the left leg just below the knee, for 5 weeks. He was also unable to extend the foot over the last few days. He gives a history of intermittent discomfort, pain, and paraesthesia in the same area for six years, which responded to physiotherapy and analgesics. There was no history of trauma.
Shows denervation of the L/tibialis anterior and peroneus longus muscles
L/common peroneal nerve: delayed latency and reduction of amplitude suggestive of a compressive lesion distal to the head of the fibula L/tibial and Sural nerves: conduction velocity is within normal limits
The common peroneal nerve is compressed by a 12 mm x 10 mm mass anterolateral to the fibula and 2.5 cm distal to the head of the fibula
The x-ray appears normal