Photobiomodulation in carpal tunnel syndrome with pain, strength, and functionality analysis: a systematic review and meta-analysis.

Background: Carpal tunnel syndrome (CTS) is characterized as a compressive neuropathy of the median nerve and has several treatments, including photobiomodulation, which can be performed with low-intensity laser therapy (LLLT) and light-emitting diodes (LEDs).

Purpose: To carry out a literature review on the effectiveness of low-intensity laser therapy (LLLT) in CTS.

Methods: This study is characterized by being a systematic review with metaanalysis. The databases included were PubMed, Embase, Cochrane, the Physiotherapy Evidence Database (PEDro), Scopus and LILACS. Also, gray literature: Google Scholar, OpenGrey and CAPES Theses and Dissertations Catalog. The search was carried out in all databases on October 11, 2023 and updated on June 06, 2024. The risk of bias was assessed using the Cochrane tool, RoB 2, by two blinded reviewers and conflicts were resolved by consensus. The outcomes of interest were pain intensity (Visual analogue scale), strength (handgrip and pinch) and hand functionality (Boston questionnaire, Levine questionnaire, Purdue Pergboard Test). Statistical analysis was carried out using RevMan 5.4.1. Continuous results were expressed as standard mean differences (95% CI), with p-value of < 0.05 considered statistically significant. The value of the I2 statistical test was calculated to test for heterogeneity between studies. A random effects model was adopted.

Results: 13 randomized controlled trials were selected from 1.613 records. In the general bias analysis, two studies (15,4%) were considered to have some relevant problems that could interfere with the quality of the study, and three (23,1%) were identified as having a high risk of bias, eight studies (61,5%) were classified as having a low risk of bias. In the meta-analysis, it was possible to observe that there were no advantages of the laser for pain (p = 0.08), nor for handgrip strength (p = 0.11), but it did produce improvements in functionality.

Conclusion: It is concluded that LLLT is an effective therapeutic modality in the treatment of CTS, improving functionality; however, despite the studies pointing to advantages for the modality in reducing pain and improving grip strength, the meta-analysis did not show this result. Even so, there is a need for more clinical trials are needed to standardize dosimetry, mainly because the primary studies showed clinical advantages of PBM.

Registration: Open Science Framework (OSF)- https://doi.org/10.17605/OSF.IO/HQCRP .