[Study on pathogenic mechanism of hemifacial spasm]

In 17 cats, areas of focal injury were induced in the facial nerve root near the brain stem by implantation of V-clamp and catgut suture. The electrophysiological examinations were made at 3 weeks after the surgery. When the mandibular branch of the facial nerve was electrically stimulated, a combined activity potential and a delayed activity could be recorded from the orbicular ocular branch of the facial nerve. The delayed activity disappeared after the motornucleu of the facial nerve was blocked with injection of 2% Lidocaine(1.5 microliter). These phenomena suggests that the artifacial synapses have been formed among the demyelinating facial nerve. The antidromic impulse of the mandibular branch of the facial nerve spread to adjacent fibers through the artifacial synapses in REZ of the facial nerve and causes the synkinases and spasm. Delayed activity may be caused by neurons of the motornucleu. Experimental lesion was also examined histologically at 3 weeks following implantation. Injured nerve showed areas of demyelination and Waller's degeneration of adjacent axons. The Nissle substances at the neurons of the motornucleu were dissolved and disappeared.