Experimental facial myokymia in cat

Abstract

Introduction – The objective of this study was to describe facial myokymia in experimental animals accompanying kainic acid affects on facial motor neurons. Material & methods – Anesthetized cats were injected with kainic acid into the pons adjacent to the facial nucleus. Facial movements appeared shortly after the injections and facial electromyographic potentials were recorded. Cats were killed up to 4 weeks later, the brainstems were processed histologically, and the number of neurons in the facial nucleus counted. Results – Cats receiving injection of kainic acid adjacent to facial nucleus all developed spontaneous writhing movements of the face ipsilateral to the injection site, clinically resembling facial myokymia in humans. Transient facial paresis, lasting several weeks, appeared in some of the cats. Facial myokymia occurred independent of histological evidence of neuronal loss in facial nucleus, whereas facial paresis occurred in all but one of the animals with significant neuronal loss in the facial nucleus. Placing a needle into the superior olive without injecting kainic acid or injections of kainic acid into cochlear nucleus was not accompanied by facial myokymia or subsequent facial paresis. Conclusion – Facial movements in cats similar to myokymia in humans accompanies kainic acid injections adjacent to the nucleus of the facial nerve.

Melatonin protects hippocampal neurons in vivo against kainic acid-induced damage in mice

“…The dosage of melatonin (5 mg/ kg) used in this study, of course, was pharmacological compared to the physiological levels of mice at the secretory peak at night (about 50 pg/ml plasma). However, melatonin's half-life in the blood is relatively short (20-40 min) while the effects of KA can persist for weeks (Mink et al, 1991;Zaaroor et al, 1997) because it is a non-degradable glutamate receptor analogue. This indicates that the blood levels of melatonin may not be a suitable indicator of tissue levels of this constituent (Menendez-Pelaez et al, 1993b).…”

Inspiratory stridor secondary to palatolingual myokymia in a Maltese dog

“…This report describes a dog with myokymia with selective involvement of palatal and lingual muscles. Apart from a single canine case report of facial myokymia, this is the only description of spontaneous focal myokymia in animals (Zaaroor and Starr 1997, Walmsley and others 2006).…”