To evaluate the pathophysiological mechanism of hemifacial spasm (HFS), we performed electrophysiological examinations, such as supraorbital nerve stimulation with orbicularis oris muscle recording and lateral spread tests, after suppressing the patient's central nervous system by administering intravenous diazepam.
Methods
Six patients with HFS were recruited. Supraorbital nerve stimulation with orbicularis oris muscle recording and the lateral spread test were performed, followed by intravenous application of 10 mg diazepam to achieve facial motor neuron suppression. Subsequently, we repeated the two electrophysiological experiments mentioned above at 10 and 20 minutes after the patients had received the diazepam intravenously.
Results
Orbicularis oris muscle responses were observed in all patients after supraorbital nerve stimulation and lateral spread tests. After the diazepam injection, no orbicularis oris muscle response to supraorbital nerve stimulation was observed in one patient, and the latencies of this response were evident as a slowing tendency with time in the remaining five patients. However, the latencies of the orbicularis oris muscle responses were observed consistently in all patients in the lateral spread test.
Conclusion
Our results suggest that ectopic excitation/ephaptic transmission contributes to the pathophysiological mechanisms of HFS. This is because the latencies of the orbicularis oris muscle responses in the lateral spread test were observed consistently in the suppressed motor neuron in our patients.
Citations
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Clinical analysis of abnormal muscle response monitoring for hemifacial spasm during microvascular decompression: a retrospective study Hanxuan Wang, Hailiang Shi, Kuo Zhang, Yang Li, Jianwei Shi, Penghu Wei, Tao Qian, Guoguang Zhao Acta Neurologica Belgica.2025; 125(2): 531. CrossRef
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Microsurgery and Neuromodulation for Facial Spasms AniruddhaA Bhagwat, Milind Deogaonkar, ChandrashekharE Deopujari Neurology India.2020; 68(8): 196. CrossRef
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