Carpal tunnel syndrome (CTS) is a disorder with a prevalence of about 5.8% for females and 0.6% for males. This study aims to determine whether intramuscular stimulation (IMS) to the pronator teres muscle subsequently reduces the severity of clinical parameters and the diameter of the median nerve.
Seventy-five individuals with a cross-sectional diameter of the median nerve of more than 2 mm were included in this randomized clinical trial. Thirty-seven individuals received IMS to the pronator teres muscle with a depth of up to 45-50 mm. The 38 individuals in the control group received an acupuncture needle at Li11 with a depth of 4-5 mm. Both groups had 7 treatments within 7 weeks. The primary outcome was the cross-section of the median nerve in the carpal tunnel. Additionally, Phalen’s test, Tinel’s sign, VAS for pain intensity, and pincer grip strength were measured.
Both IMS subjects and controls showed significant reductions in the cross-section of the median nerve from baseline to follow-up (p < 0.001 and p = 0.002 respectively). The IMS group had the largest change, but the difference in change between the groups was not significant (p = 0.39). On all clinical tests, IMS subjects showed significant improvement from baseline compared with the control group (largest p = 0.002).
In this study we found that IMS to the pronator teres muscle significantly improved all clinical variables measured, compared with the group receiving acupuncture. Furthermore, the cross-section of the median nerve reduced over time for both groups. IMS may be a low-risk alternative while patients are waiting for surgery.
Clinicaltrials. gov Identifier: NCT01102868. Retrospectively registered: March 29th 2010.

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