| A mathematical model for top-shelf vertigo: the role of sedimenting otoconia in BPPV. | |
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MedLine Citation:
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PMID: 15212918 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Benign paroxysmal positional vertigo (BPPV) is a mechanical disorder of the vestibular system in which calcite particles called otoconia interfere with the mechanical functioning of the fluid-filled semicircular canals normally used to sense rotation. Using hydrodynamic models, we examine the two mechanisms proposed by the medical community for BPPV: cupulolithiasis, in which otoconia attach directly to the cupula (a sensory membrane), and canalithiasis, in which otoconia settle through the canals and exert a fluid pressure across the cupula. We utilize known hydrodynamic calculations and make reasonable geometric and physical approximations to derive an expression for the transcupular pressure DeltaPc exerted by a settling solid particle in canalithiasis. By tracking settling otoconia in a two-dimensional model geometry, the cupular volume displacement and associated eye response (nystagmus) can be calculated quantitatively. Several important features emerge: (1) a pressure amplification occurs as otoconia enter a narrowing duct; (2) an average-sized otoconium requires approximately 5 s to settle through the wide ampulla, where DeltaPc is not amplified, which suggests a mechanism for the observed latency of BPPV; and (3) an average-sized otoconium beginning below the center of the cupula can cause a volumetric cupular displacement on the order of 30 pL, with nystagmus of order 2 degrees/s, which is approximately the threshold for sensation. Larger cupular volume displacement and nystagmus could result from larger and/or multiple otoconia. |
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Authors:
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Todd M Squires; Michael S Weidman; Timothy C Hain; Howard A Stone |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of biomechanics Volume: 37 ISSN: 0021-9290 ISO Abbreviation: J Biomech Publication Date: 2004 Aug |
Date Detail:
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Created Date: 2004-06-23 Completed Date: 2005-02-16 Revised Date: 2009-11-11 |
Medline Journal Info:
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Nlm Unique ID: 0157375 Medline TA: J Biomech Country: United States |
Other Details:
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Languages: eng Pagination: 1137-46 Citation Subset: IM |
Affiliation:
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Departments of Applied and Computational Mathematics and Physics, California Institute of Technology, Pasadena, CA 91125, USA. tsquires@acm.caltech.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Calculi
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physiopathology Ear, Inner / physiopathology* Humans Models, Biological Nystagmus, Pathologic / etiology Otolithic Membrane / physiopathology* Semicircular Canals / physiopathology Time Factors Vertigo / etiology*, physiopathology |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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