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Superior Vestibular Nerve SectioningExperimental Studies in Squirrel Monkeys
Marion V. Filippone, MD;
Makoto Igarashi, MD;
Hideo Miyata, MD;
Alfred C. Coats, MD;
Bobby R. Alford, MD
Arch Otolaryngol. 1975;101(4):241-245.
Abstract
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Spontaneous, positional, and paroxysmal positional nystagmus were studied before and after sectioning the superior division of the vestibular nerve and the anterior vestibular artery in squirrel monkeys. Histopathologic study of the temporal bones confirmed the degeneration of the macula utriculi with release of statoconia, but failed to identify the released utricular statoconia within the vestibular endolymphatic space in any animal.
Postoperatively the animals consistently demonstrated direction-fixed spontaneous nystagmus until the end of the experiment (five months). Positional tests and Dix-Hallpike maneuver occasionally changed the intensity of the spontaneous nystagmus, but never elicited paroxysmal positional nystagmus.
Possible reasons for not demonstrating paroxysmal positional nystagmus in the squirrel monkey are as follows: a resorption of statoconia; slight morphological alteration of the sensory epithelia of the posterior cristae; interference of the posterior crista function due to partial collapse of the membranous ampulla; the existence of interspecies difference; or possibly a faulty hypothesis regarding the etiologic mechanism of benign paroxysmal positional vertigo.
Author Affiliations
From the Department of Otorhinolaryngology and Communicative Sciences, Baylor College of Medicine, Houston.
Footnotes
Accepted for publication Sept 20, 1974.
Read before the Research Committee Meeting of the American Academy of Ophthalmology and Otolaryngology, Dallas, Sept 22, 1973.
Reprint requests to the Department of Otorhinolaryngology and Communicative Sciences, Baylor College of Medicine, Houston, TX 77025 (Dr. Filippone).
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