Pathophysiology of hemifacial spasm

We studied 59 patients with hemifacial spasm before decompression of the facial nerve in the cerebellopontine angle. Fifty-three patients were reexamined 1 week later, and 30 patients after 2 to 8 months. Within 1 week, ephaptic transmission disappeared in 23% and changed from bidirectional to unidirectional in 45%. After discharges disappeared in 64% and were mild in 34%. Synkinesis after supraorbital nerve stimulation disappeared in 53%, and the blink reflex amplitude became normal. After 2 to 8 months, ephaptic transmission was abolished in 73% and unidirectional in 17%. After-discharges and synkinesis disappeared in 90%, and the latency of the blink reflex decreased. It is concluded that decompression stops ectopic/ephaptic excitation due to decrease in the interstitial resistance, and enables remyelination.

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