[Electrophysiologic diagnosis of carpal tunnel syndrome in 1993. Apropos 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 median-ulnar latency difference measurement among sophisticated nonroutine tests, and of the centimetric test as the gold standard for the diagnosis of carpal tunnel syndrome.