Peripheral nerve entrapment and injury in the upper extremity.

Peripheral nerve injury of the upper extremity commonly occurs in patients who participate in recreational (e.g., sports) and occupational activities. Nerve injury should be considered when a patient experiences pain, weakness, or paresthesias in the absence of a known bone, soft tissue, or vascular injury. The onset of symptoms may be acute or insidious. Nerve injury may mimic other common musculoskeletal disorders. For example, aching lateral elbow pain may be a symptom of lateral epicondylitis or radial tunnel syndrome; patients who have shoulder pain and weakness with overhead elevation may have a rotator cuff tear or a suprascapular nerve injury; and pain in the forearm that worsens with repetitive pronation activities may be from carpal tunnel syndrome or pronator syndrome. Specific history features are important, such as the type of activity that aggravates symptoms and the temporal relation of symptoms to activity (e.g., is there pain in the shoulder and neck every time the patient is hammering a nail, or just when hammering nails overhead?). Plain radiography and magnetic resonance imaging are usually not necessary for initial evaluation of a suspected nerve injury. When pain or weakness is refractory to conservative therapy, further evaluation (e.g., magnetic resonance imaging, electrodiagnostic testing) or surgical referral should be considered. Recovery of nerve function is more likely with a mild injury and a shorter duration of compression. Recovery is faster if the repetitive activities that exacerbate the injury can be decreased or ceased. Initial treatment for many nerve injuries is nonsurgical.