Local steroid injection in carpal tunnel syndrome(CTS) is widely practised for the relief of symptoms such as pain and paresthesias. We evaluated the effects of the injection with electrophysiologic changes and improvement in pain and paresthesias.

27 patients, 40 cases with carpal tunnel syndrome diagnosed clinically and electrophysiologically were injected with 40mg of triamcinolone acetonide. Patients were reevaluated with the visual analogue scale and electrophysiologic parameters after 2 to 4 weeks. Then we split up the patients into "excellent", "good" ,"poor" group by the degree of responses to the injections. In order to predict the injection effect, we analyzed several clinical and electrophysiologic factors: duration of symptoms, Phalen test, prolongation of distal motor latency of the median nerve, denervation evidence of the abductor pollicis brevis muscle.

Symptom relief was noted in the 89% of the cases[excellent(75%), good(14%)], and there was no statistically significant correlation between any of the above four factors and the degree of the symptom responses. Among the electrophysiologic parameters motor distal latency, motor residual latency, sensory onset and peak latency, median to radial sensory onset and peak latency difference reflected the clinical improvements(p＜0.05). But there was some cases that improved clinically but deteriorated electrophysiologically(2 cases in motor distal latency, 5 cases in motor residual latency, 1 case in sensory peak latency, none in sensory onset latency).

In conclusion we find that local steroid injection in CTS is an effective therapeutic modality for the symptom remission and it also showed changes in electrophysiologic parameters. And among these parameters sensory distal latency seems to be the most appropriate electrophysiologic parameter which best reflects the improvement of pain and paresthesias.