Pressure and nerve lesion in the carpal tunnel.

In 16 patients, where the diagnosis carpal tunnel syndrome was electrophysiologically confirmed, the pressure between the median nerve and the carpal ligament was measured peroperatively. At rest the pressure was 18-64 mmHg, mean 31 mmHg. Passive volar and dorsal wrist flexion increased the pressure about three times. Isometric or isotonic maximal contractions of wrist and finger muscles, elicited by tetanic nerve stimulation increased the pressure to three to six times the resting value. These high pressures may be one of the causes of the nerve lesion in the carpal tunnel syndrome.