Increased electromyographic activity of the abductor pollicis brevis and hand strength deficits in women with carpal tunnel syndrome: A cross-sectional study.

Abstract

Background: Carpal tunnel syndrome (CTS) can impact hand function, potentially altering muscle activity and strength during common manual tasks. Understanding these changes is essential for developing effective interventions.

Purpose: To verify if there are differences in electromyographic activity of wrist and hand muscles and in hand strength between women with and without CTS during sustained isometric grip and pinch strength tasks.

Study design: Cross-sectional study.

Methods: The study included 26 women diagnosed with CTS by a hand surgeon and a control group of 22 women without CTS. Electromyographic activities of the extensor carpi ulnaris (ECU), extensor carpi radialis longus and brevis, flexor carpi ulnaris, flexor digitorum superficialis, and abductor pollicis brevis (APB) were recorded during sustained grip and pulp-to-pulp pinch tasks. Muscle activity was quantified using the root mean square, and hand strength was measured with a Hand Grip Electronic Dynamometer, focusing on peak strength and the average over the last 60% of each task.

Results: Women with CTS showed a significant increase in root mean square of the APB during both grip and pinch tasks, and an increase in ECU activity during the pinch task. Additionally, the CTS group exhibited decreased peak strength and lower average strength over the last 60% of both tasks compared to controls.

Conclusions: Women with CTS demonstrate increased muscle activity in the APB during both grip and pinch tasks and in the ECU during pinch, along with significant deficits in hand strength. These findings suggest that CTS is associated with impaired muscle function and strength, underscoring the importance of targeted interventions to improve hand function in this population.