Mononeuropathy of the medial branch of the deep peroneal nerve in a scuba diver

Peripheral mononeuropathies occur only rarely in association with decompres sion illness. The sites previously reported to be affected are areas of pot ential entrapment in which a peripheral nerve traverses a confined area. In these instances, the pathophysiology has been presumed to be mechanical pr essure in an enclosed space by a gas bubble. A rare case is now presented o f a peripheral mononeuropathy of the medial branch of the deep peroneal ner ve in a scuba diver following surfacing from a 195 foot dive. This case dif fers from prior reports of mononeuropathy in association with decompression illness in that the affected nerve does not traverse a confined site in wh ich mechanical compression by a gas bubble is likely. The mechanism of inju ry is hypothesized to be a manifestation of decompression illness with a ga s bubble causing blood flow obstruction and an ischemic infarct.