Local injection versus surgery in carpal tunnel syndrome: neurophysiologic outcomes of a randomized clinical trial

The aim of our study was to characterize the neurophysiologic outcomes in a randomized clinical trial comparing local corticosteroid injection and decompressive surgery in idiopathic carpal tunnel syndrome.

Clinical and neurophysiologic assessments were done at baseline and 12 months after treatment. Four parameters were evaluated in the nerve conduction study (NCS): distal motor latency, motor amplitude, sensory conduction velocity and sensory amplitude. Statistic signification was established by the Student's t test, independent and paired samples, and Mann-Whitney test. Repeated measures analysis of variance was used by the three domains of symptoms. Correlations between the changes showed in clinical parameters and those evidenced by electromyography were calculated by the Pearson's test.

Both groups of therapy were comparable at baseline. In 95 wrists, a second NCS was done 12 months post-treatment. Although clinical outcome improved in a similar way in both groups, we found statistically significant improvement in three (distal motor latency, sensory conduction velocity and sensory amplitude) of four neurophysiologic parameters only in the surgery group, when compared to baseline values.

Although local corticosteroid injection and decompressive surgery are clinically effective in reducing symptoms of carpal tunnel syndrome, only surgery results in an improvement of the neurophysiologic parameters, at 12-months follow-up.

Only decompressive surgery allows resolution of neurophysiologic changes. The symptoms of the syndrome are resolved with corticosteroid injections.