THE NUMB ARM AND HAND

Trauma and compression along the course of the median, ulnar or radial nerve from the brachial plexus to the fingers may cause pain, weaknes s, numbness or tingling of the upper extremity. Diabetes, smoking, alc ohol consumption, rheumatoid arthritis and hypothyroidism are risk fac tors for nerve entrapment, although these disorders typically produce bilateral symptoms. Carpal tunnel syndrome, the most common nerve entr apment condition, results from median nerve compression at the wrist. The diagnosis is suggested by decreased pain sensation and numbness in the thumb and index and middle fingers; symptoms are reproduced by wr ist hyperflexion and median nerve percussion. Volar splinting and ster oid injection often ameliorate symptoms. Decreased sensation of the li ttle finger and the ulnar aspect of the ring finger, along with intrin sic muscle weakness, may be caused by cervical radiculopathy, thoracic outlet syndrome or compression of the ulnar nerve above the elbow (cu bital tunnel syndrome) or at the wrist (ulnar tunnel syndrome). Electr omyography and radiography may help differentiate these conditions. Ra dial tunnel syndrome occasionally accompanies inflammation of the comm on wrist extensors and lateral epicondylitis (''tennis elbow''). A rad ial nerve block can help exclude concomitant radial tunnel syndrome in patients with symptoms of lateral epicondylitis.