Background

Acupuncture is widely used in modulating brain excitability and motor function, as a form of complementary and alternative medicine. However, there is no existing meta-analysis evaluating the effectiveness and safety of acupuncture on corticospinal excitability (CSE), and the credibility of the evidence has yet to be quantified.

Objective

This study was designed to assess the efficacy and safety of electroacupuncture (EA) and manual acupuncture (MA) in enhancing brain excitability, specifically focusing on CSE as measured by transcranial magnetic stimulation (TMS).

Search strategy

This study followed a systematic approach, searching 9 databases up to August 2024 and examining grey literature, in compliance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Inclusion criteria

Studies were included if they compared the clinical efficacy of EA or MA with sham acupuncture, no treatment or usual training.

Data extraction and analysis

Three investigators independently conducted literature screening, data extraction, and risk of bias assessment. The primary outcome focused on motor-evoked potentials as measured by TMS, with treatment effects quantified using mean differences or standardized mean differences between pre- and post-treatment. Subgroup analyses were conducted using mixed-effects models, while random-effects or fixed-effects models were used to estimate average treatment differences across studies.

Results

Based on 34 studies involving 1031 adults, acupuncture techniques significantly enhanced CSE. EA had a greater impact than MA, with effect sizes of 0.53 mV vs 0.43 mV (95% confidence interval [CI]: [0.30, 0.76], P < 0.00001 vs 95% CI: [0.28, 0.59], P < 0.00001). The 5 most frequently used acupoints were LI4 (Hegu, 32 times), ST36 (Zusanli, 10 times), LI11 (Quchi, 7 times), TE5 (Waiguan, 6 times), and GB34 (Yanglingquan, 5 times).

Conclusion

This systematic review indicates that both EA and MA could effectively and safely enhance CSE, bringing the corticospinal pathway closer to the threshold for firing, which may ultimately improve motor function. LI4, ST36, LI11, TE5 and GB34 are the most commonly used acupoints.

Key words: Acupuncture, Brain excitability, Corticospinal excitability, Motor-related acupoints, Motor function