PERIPHERAL-NERVE INJURIES IN THE ATHLETE

Peripheral nerves are susceptible to injury in the athlete because of the excessive physiological demands that are made on both the neurolog ical structures and the soft tissues that protect them. The common mec hanisms of injury are compression, traction, ischaemia and laceration. Seddon's original classification system for nerve injuries based on n europhysiological changes is the most widely used. Grade 1 nerve injur y is a neuropraxic condition, grade 2 is axonal degeneration and grade 3 is nerve transection. Peripheral nerve injuries are more common in the upper extremities than the lower extremities, tend to be sport spe cific, and often have a biomechanical component. While the more acute and catastophic neurological injuries are usually obvious, many remain subclinical and are not recognised before neurological damage is perm anent. Early detection allows initiation of a proper rehabilitation pr ogramme and modification of biomechanics before the nerve injury becom es irreversible. Recognition of nerve injuries requires an understandi ng of peripheral neuroanatomy, knowledge of common sites of nerve inju ry and an awareness of the types of peripheral nerve injuries that are common and unique to each sport. The electrodiagnostic exam, usually referred to as the 'EMG', consists of nerve conduction studies and the needle electrode examination. It is used to determine the site and de gree of neurological injury and to predict outcome. It should be perfo rmed by a neurologist or physiatrist (physician specialising in physic al medicine and rehabilitation), trained and skilled in this procedure . Timing is essential if the study is to provide maximal information. Findings such as decreased recruitment after injury and conduction blo ck at the site of injury may be apparent immediately after injury but other findings such as abnormal spontaneous activity may take several weeks to develop. The electrodiagnostic test assists with both diagnos is of the injury and in predicting outcome. Proximal nerve injuries ha ve a poorer prognosis for neurological recovery. The most common perip heral nerve injury in the athlete is the burner syndrome. Though prima rily a football injury, burners have been reported in wrestling, hocke y, basketball and weight-lifting as a result of acute head, neck and/o r shoulder trauma. Most burners are self-limiting, but they occasional ly produce permanent neurological deficits. The axillary nerve is comm only injured with shoulder dislocations but is also susceptible to inj ury by direct compression. The sciatic and common peroneal nerves can be injured by trauma. The suprascapular, musculocutaneous, ulnar, medi an and tibial nerves are susceptible to entrapment. The long thoracic and femoral nerves can be injured by severe traction.