Distal Electroacupuncture Modulates Maladaptive Brainstem and Motor Cortex Plasticity to Alleviate Hemifacial Spasm

Background Hemifacial spasm (HFS) is characterized by maladaptive brain plasticity, yet whether modulating this plasticity can alleviate symptoms remains unclear. Objective To evaluate the efficacy of electroacupuncture (EA)—a form of peripheral nerve stimulation—for HFS and elucidate its underlying neuroplastic mechanisms. Methods In this randomized, double‐blind, sham‐controlled trial (conducted 2016–2023), 84 HFS patients and 84 healthy controls were enrolled. Patients received 30 sessions of distal (hand), local (facial), or sham EA over 15 weeks. Clinical outcomes included Jankovic and Global Rating Scales. Physiological markers, including lateral spread response (LSR), synkinetic response (SR), and blink reflex (BR) excitability, were measured by electromyography (EMG). Motor cortex (M1) excitability was quantified via motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS). Parameter‐probing experiments in healthy controls identified optimal stimulation characteristics. Results At baseline, HFS patients exhibited profound brainstem (BR R1/R2: P < 0.001) and facial M1 hyperexcitability versus controls. Low‐frequency, low‐intensity hand EA (2 Hz, 0.5–1 mA) significantly reduced Jankovic scores by 3.32 points (95% CI −4.12 to −2.52; P < 0.001; Cohen's d = 1.86) versus sham EA. This clinical improvement was mechanistically linked to a significant suppression of LSR ( P < 0.01) and BR amplitude ( P < 0.001), a reduction in facial M1 excitability ( P < 0.05), and a compensatory increase in hand M1 excitability ( P < 0.001). Notably, these neurophysiological and clinical benefits were maintained for 6 months post‐treatment. Conclusion Distal low‐frequency, low‐intensity peripheral stimulation effectively alleviates HFS by modulating maladaptive brainstem and M1 plasticity. These findings highlight the potential of this approach as a promising neuromodulatory strategy for hyperkinetic movement disorders.