Prediction of outcome of decompression for carpal tunnel syndrome.

45 patients (55 hands) with carpal tunnel syndrome treated surgically have been studied. Painful nocturnal paraesthesiae occurred in patients with short histories and was a good prognostic feature. Electromyography proved of value in assessing motor lesions and the degree of the process. The first sign of muscle involvement was fibrillation potential. In longer histories, an increased amount of polyphasic potentials and reduced voluntary pattern was seen. The reduced pattern is reversible in cases of short duration and the absence of muscle wasting. In cases with marked alteration and signs of chronic muscle degeneration, the prognosis for pain is good, but not so for the neurological deficit. The nerve conduction velocity improved quickly after decompression of the median nerve in accordance with the complaints of the patient. Electrophysiological methods proved their value in staging and follow-up.