Entrapment of Superficial Peroneal Nerve
Uncommon. Arises from L4, L5 &S1. A number of injuries can affect the nerve and its branches.
Can be stretched in severe ankle sprains or supinating feet. Usually occurs where nerve pierces deep fascia to become superficial. The medial dorsal cutaneous branch can be irritated at base of first metatarsal from a bony prominence and footwear. Also pressure from boots or from direct trauma.
Pain, burning, numbness and tingling along dorsolateral border of foot – especially with exercise; improves with rest. Some have vague discomfort on lateral ankle and foot. May be tender to palpation at site of entrapment. May be able to elicit Tinnel’s sign by percussion of nerve where it becomes superficial – about 7-9cm above ankle.
Relief of traction on nerve (may need orthoses if foot supinating). Cortisone injection at entrapment site; NSAID’s; activity modification; surgical decompression.