A patient shown to have wasting at the interdigital web spaces, experiences numbness of the ring finger and exhibits Wartenberg sign on physical examination most likely is suffering from:
A. Cubital tunnel syndromeThe ulnar nerve also innervates the dorsal surface of the small finger and ulnar side of the ring finger, so numbness in these areas can be explained by cubital tunnel syndrome. The patient may also report weakness in grip due to effects on the flexor digitorum profundus (FDP) tendons to the ring and small fingers and the intrinsic hand muscles. Patients with advanced disease may complain of inability to fully extend the ring and small finger interphalangeal (IP) joints. Physical examination for cubital tunnel syndrome begins with inspection. Look for wasting in the hypothenar eminence and the interdigital web spaces. When the hand rests flat on the table, the small finger may rest in abduction with respect to the other fingers; this is called Wartenberg sign. Tinel sign is often present at the cubital tunnel. Elbow flexion test will often be positive. Grip strength and finger abduction strength should be compared to the unaffected side. Froment sign can be tested by placing a sheet of paper between the thumb and index finger and instructing the patient to hold on to the paper while the examiner pulls it away without flexing the finger or thumb (this tests the strength of the adductor pollicis and first dorsal interosseous muscles). If the patient must flex the index finger and/or thumb (FDP-index and flexor pollicis longus [FPL] , both median nerve supplied) to maintain traction on the paper, this is a positive response.