ELECTROPHYSIOLOGIC DIAGNOSIS OF CARPAL-TUNNEL SYNDROME IN 1993 - A REVIEW OF 100 CASES

A range of diagnostic investigations and threshold values were evaluated prospectively in 100 cases of symptomatic carpal tunnel syndrome in 60 patients. Proportions of cases with abnormal findings were 44/100 for the needle study, 56/100 for distal motor latency, 65/100 for digit-to-wrist orthodromic sensory conduction velocity, and 78/100 for palm-to-wrist orthodromic sensory conduction velocity. Among the 22 patients who had normal findings for these conventional parameters, 5 had a double peak after global fourth digit stimulation, 20 had a fourth digit median-ulnar latency difference of 0.40 msec or more, and 22 had an abnormal centimetric test. These data highlight the value of palm-to-wrist orthodromic sensory conduction velocity measurements among routine tests, of fourth digit medianulnar latency difference measurement among sophisticated nonroutine tests, and of the centimetric test as the gold standard for the diagnosis of carpal tunnel syndrome.