Evaluation of portable nerve conduction testing in the diagnosis of carpal tunnel syndrome

A portable nerve conduction testing instrument (the electroneurometer) was investigated to evaluate its sensitivity and specificity in the diagnosis of carpal tunnel syndrome. The preoperative electroneurometer measurements of distal motor and sensory latencies of the median nerve in 43 consecutive hands with a dear diagnosis of carpal tunnel syndrome (typical history, clinical signs, and complete symptom relief after surgery) were analyzed. Distal motor and sensory latencies of the median nerve were also measured in 60 hands of asymptomatic healthy volunteers. The sensitivity of the device in the hands with carpal tunnel syndrome was 58% for distal motor latency (upper limit of normal, 4.4 ms) and 65% for distal sensory latency (upper limit of normal, 3.5 ms). The specificity of the instrument in the control hands was 87% and 92% for distal motor and sensory latency, respectively. Receiver operating characteristic curves showed distal sensory latency measurement to be a superior diagnostic test, with 3.3 ms as optimal upper limit of normal, giving a sensitivity of 74% and a specificity of 87%. The sensitivity and specificity of the device are comparable to those reported for conventional nerve conduction studies.