Management of extreme carpal tunnel syndrome: evidence from a long-term follow-up study.

Extreme carpal tunnel syndrome (CTS) is characterized by severe thenar atrophy, plegia of the abductor pollicis brevis (APB), fixed sensory deficit in the median nerve distribution, and absence of median motor and sensory responses on electrophysiological examination. In this study we report long-term follow-up of 37 patients with extreme CTS. Of the 24 patients with idiopathic extreme CTS, 9 were untreated, and 3 received conservative treatment. At follow-up, none of these patients showed objective or electrophysiological improvement, and all but 1 still reported positive symptoms. Conversely, 12 patients (14 hands) who underwent carpal tunnel release showed: resolution of positive symptoms in all but 1 hand; reappearance of median compound muscle action potentials (4.2 +/- 0.6 mV); reappearance of sensory nerve action potentials in all but 1 (7.9 +/- 0.8 microV); improvement of APB strength to grade 4 or 5 on the Medical Research Council scale in 11 hands; and resolution of hypesthesia in 1 hand. Six of 13 patients with non-idiopathic extreme CTS were operated. Of the 6, we found no or poor reinnervation in 3 patients, restoration of nerve responses and normal APB strength but no relief from pain and/or paresthesia in 2, and full recovery in 1. If untreated, extreme CTS is an irreversible condition. Although the outcome is considered to be disappointing in such cases, carpal tunnel release provides long-term relief, significant sensorimotor reinnervation, and improvement of motor deficit in most patients. It should be considered to be the first-choice treatment for idiopathic extreme CTS. Associated diseases do not necessarily imply a poor surgical outcome.