[Early electroneurographic diagnosis of carpal tunnel syndrome (author's transl)]

A comparison of distal motor latencies after stimulation of the median and ulnar nerves proximal to the ligamentum carpi transversum and recording from the thenar muscles shows: a) in normal subjects (99 measurements) a 0,7 msec longer latency after stimulation of the ulnar nerve, b) in generalized polyneuropathies in 46% (n = 48) a reversal of the two motor latencies, i.e., a longer median than ulnar nerve latency. c) in manifest carpal tunnel syndromes with pathologically prolonged motor latencies this reversal in all cases; d) in carpal tunnel syndromes with only pathologically prolonged sensory latencies in 11 out of 13 patients a reversal of motor latencies; e) in patients with carpal tunnel syndromes a reversal of motor latencies in 65% (n = 46) on the clinically symptom-free side. It is concluded that a reversal of distal motor latencies may be the earliest sign of a carpal tunnel syndrome, if a generalized polyneuropathy is excluded and typical symptoms are reported.