Pathological and Functional Changes Following Hemisection of the Lateral Ampullary Nerve

Abstract

An attempt was made to section the canalicular branch of the lateral ampullary nerve in the cat. In successful cases the section was associated with degeneration of both sensory and marginal epithelium and the stroma. The animals showed signs of an acute vestibular disorder consisting of disequilibrium, spontaneous nystagmus toward the unoperated ear, type III positional nystagmus, perverted nystagmus in response to caloric irrigation on the operated side, and a directional preponderance toward the unoperated ear during optokinetic, caloric and rotatory tests. Section of superior and/or lateral ampullary nerves to a certain extent mimicked the clinical signs of a labyrinthectomy. The clinical implications of the vestibular disorder associated with damage localized to the crista ampullaris is discussed.