Practica Oto-Rhino-Laryngologica

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The electro-physiological and morphological changes in the brainstem of the cats occurred after galvanic stimulation through the retro-auricular electrode. The resulting changes were topographically studied.
Otoneurologically healthy 18 cats were divided into three groups: the control group, the group receiving 2mA of direct current for 20 minutes (“2mA group”) and the group receiving 10mA for 20min. (“10mA group”). Auditory brainstem response (ABR) was measured in all cats at several designated time periods pre- and post-stimulation under light general anesthesia. The latency and amplitude of ABR waves I to V were calculated and compared. After the completion of ABR measurement, the animals'brain tissues were extracted according to the standardized vital perfusion-fixarion method. The cortical area, where the indifferent electrode was embedded, and the brainstem were dissected for histopathological specimens. Specimens were stained using HE stains, Nissl, Klüver & Barrera and Bodian staining methods.
The findings were as follows:
1. Eye deviation induced by galvanic stimulation was obseved in all animals in the “2mA group” and the “10mA group”.
2. Changes of latency and amplitude of the I, III, and V waves on the right side (the stimulated side) were significant in the “10mA group” compared to the control group. Similarly, the changes of latency of the I and V waves on the left side (non-stimulated side) differed significantly between the “10mA group” and the “control group”.
3. Disappearance of the II, III, IV and V waves on the stimulated side and of the II, III, and V waves on the non-stimulated side were observed in the “10mA group”. Only the V wave on both sides of the “2mA group” disappeared.
4. Hsstopathological survey of the brainstem of the “10mA group” revealed that changes occurred in the ipsilateral vestibular nuclei, cochlear nuclei, lateral lemniscus, nucleus of the facial nerve, nucleus of the abducent nerve and facial nerve bundle; and also in the bilateral reticular formation, medial longitudinal fasciculus, superior olibary nucleus and commissure of inferior colliculus.

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