Neurological research
-
Neurological research · Oct 1994
Comparative StudyRecordings from the facial motonucleus in rats with signs of hemifacial spasm.
We recorded evoked potentials from the facial motonucleus of rats in response to electrical stimulation of the temporal branch of the facial nerve in which chronic irritation from a blood vessel had caused the development of an abnormal muscle response. The abnormal muscle response that can be recorded from face muscles that are innervated by one branch of the facial nerve in response to electrical stimulation of a different branch is regarded to be a sign of hemifacial spasm. In the recordings from the motonucleus in rats that showed such an abnormal muscle response (model rats) there was a late component at a latency of about 5 msec, in addition to the early component with a latency of 1.5-2.5 msec that is also observed in normal rats. ⋯ This value is close to the sum of the conduction time from the motonucleus to the mentalis muscle (2 msec) and the latency of the late response from the motonucleus (5 msec). Similar results were obtained in rats in which the facial nerve had been chronically stimulated electrically and which had developed an abnormal muscle response. The results of this study further support the hypothesis that the hyperactivity of the facial motonucleus is the pathophysiology of hemifacial spasm.