A randomized controlled trial on the effectiveness of mirror therapy in improving strength, range of movement and muscle activity, in people with carpal tunnel syndrome

Abstract

Background: There is little information on the potential effects of mirror therapy (MT) on motor recovery in individuals with Carpal Tunnel Syndrome (CTS).

Purpose: To compare the effectiveness of a MT protocol versus a therapeutic exercise (TE) protocol, in improving strength, range of motion (ROM), muscle activity, pain, and functionality in patients with CTS.

Study design: Randomized clinical trial.

Methods: Thirty-nine participants with unilateral CTS were divided into two groups: (i) MT group (n = 20) that followed an exercise protocol applied to the unaffected hand reflected in a mirror, and (ii) TE group (n = 19) that followed the same exercise protocol using the unaffected hand but without a mirror. Strength, wrist ROM, muscle activity, pain and functionality, were assessed at baseline (T0), after treatment (T1) and one month after treatment (T2).

Results: At T1, the MT group showed significantly higher wrist flexion-extension ROM compared to TE (p = 0.04, d = 0.8), maintained at T2 (p = 0.02, d = 0.8). No significant changes were observed in ulnar-radius deviation, pronosupination, or fatigue following either MT or TE (p > 0.05). MT exhibited enhanced handgrip strength at T1 (p = 0.001, d = 0.7), as well as an increase in the extensor carpi radialis (ECR) and flexor carpi radialis (FCR) maximum muscle activity (p = 0.04, d = 1.0; p = 0.03, d = 0.4). At T1, both groups decreased pain (p = 0.002, d = 1.1; p = 0.02, d = 0.7), and improved functionality (p < 0.001, d = 0.8; p = 0.01, d = 0.5) (MT and TE respectively).

Discussion: MT led to enhancements in wrist flexion-extension movement, handgrip strength and functionality unlike TE. MT notably increased muscle activity, particularly in the ECR and FCR muscles.

Conclusions: MT is a favorable strategy to improve wrist flexion-extension ROM, handgrip strength, ECR and FCR muscle activity, and functionality in people with unilateral CTS.

Trial registration: ClinicalTrials.gov NCT05115396.

Keywords: Carpal tunnel syndrome; Cross-education; Hand; Mirror therapy; Strength.