Improved inching method for the diagnosis and prognosis of carpal tunnel syndrome.

A modified sensory "inching" method for the electrodiagnosis of carpal tunnel syndrome (CTS) is described. The median nerve as stimulated at the cubital portion, with 8 channel recording electrodes placed along the nerve across the carpal tunnel. In most of the CTS cases, there was a conductive abnormality from 3 to 4.5 cm distal to the proximal ending of the flexor retinaculum. Subjects' values, obtained by subtracting the theoretical latency from the measured latency, which were more than 0.6 ms, could not be improved by conservative therapy. As we could determine from subtle change at the short span of nerve conduction, below the electrodes from the proximal to the affected site of the carpal tunnel, this method provides high sensitivity and specificity for the diagnosis of CTS.