Distal electrical stimulation produces facial nerve regenerative and anti-synkinetic effects comparable to proximal electrical stimulation

Several reports indicate that electrical stimulation (ES) promotes peripheral nerve regeneration, primarily when applied proximal to the site of injury. However, when considering its application in facial nerve palsy, which is most commonly of viral origin, the lesion is typically located within the temporal bone, rendering proximal stimulation challenging. Therefore, despite its therapeutic potential, ES has not been successfully translated into clinical treatment for facial nerve palsy.

The present study investigated whether distal ES could achieve regenerative and anti-synkinetic effects comparable to those of proximal stimulation using a rat facial nerve crush model. The animals were divided into three groups: no stimulation, proximal ES, and distal ES. Functional recovery was assessed using the eye blink reflex and whisker movement, whereas synkinesis was evaluated using electromyography and retrograde labeling.

Both proximal and distal ES significantly promoted functional recovery and reduced synkinesis compared to controls. Importantly, the effects of distal stimulation were comparable to those of proximal stimulation across all assessments. These findings suggest that stimulation applied at a site distal to the injury—which, unlike proximal stimulation, does not require surgical exposure of the lesion itself—can achieve regenerative and anti-synkinetic effects comparable to proximal stimulation.

This proof-of-concept evidence, while not a direct demonstration of clinical efficacy, supports further preclinical evaluation of distal ES as a potential therapeutic strategy for facial nerve palsy. We would like to thank Editage (www.editage.jp) for the English language editing. This study was supported by JSPS KAKENHI (Grant Number JP26K12587).

The funding body had no role in the design of the study; collection, analysis, and interpretation of data; or writing of the manuscript. Department of Plastic and Reconstructive Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan Department of Plastic and Reconstructive Surgery, International University of Health and Welfare Ichikawa Hospital, 5-11-13 Sugano, Ichikawa-shi, Chiba, 272-8513, Japan Department of Mechanical Engineering, Keio University, Yokohama, Kanagawa, 223-8522, Japan Masafumi Yamaga, Hiroaki Sugimoto & Norihisa Miki Division of Brain Sciences, Institute for Advanced Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan Hikaru Ikuta, Yuta Kamikawa & Kenji F. Tanaka The authors declare no competing interests.

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