Model Experiment of Benign Paroxysmal Positional Vertigo Mechanism Using the Whole Membranous Labyrinth

ArticleinActa Oto-Laryngologica 123(4):515-8 · June 2003with8 Reads
DOI: 10.1080/0036554021000028094 · Source: PubMed
Whole membranous labyrinths of bullfrogs were used in order to replicate the human vestibule. The posterior semicircular canals (PSCs) were exposed, leaving the remaining membranous labyrinth encapsulated in the otic capsule. Vibration was applied to the surface of the bony capsule using a conventional surgical drill in order to dislodge the otoconia from the utricle. The position of the preparation was controlled so that the dislodged otoconia were attached to the cupular surface. This was regarded as a cupulolithiasis model. The action potentials changed instantaneously according to the gravitational force on the cupula. When the otoconia were dislodged and held within the PSC lumen, the position of the whole preparation was changed so that the otoconia moved back and forth within the canal lumen. This is a model of canalolithiasis. The action potentials changed in combination with the otoconial movement after a latent period. Both cupulolithiasis and canalolithasis are potentially valid mechanisms of benign paroxysmal positional vertigo (BPPV). However, canalolithiasis is the most likely mechanism of BPPV, which is usually characterized by nystagmus of short duration and long latency. A vibratory stimulus was able to detach the otoconia from the utricle, suggesting that mechanical insult could be a possible etiology of BPPV.
    • "Cupulolithiasis may exist in the posterior canal. Compared with canalolithiasis, the cupulolithiatic type of PC-BPPV tends to have shorter latency and longer time constant (i.e., it is more persistent).43 "
    [Show abstract] [Hide abstract] ABSTRACT: Benign paroxysmal positional vertigo (BPPV) is characterized by brief recurrent episodes of vertigo triggered by changes in head position. BPPV is the most common etiology of recurrent vertigo and is caused by abnormal stimulation of the cupula by free-floating otoliths (canalolithiasis) or otoliths that have adhered to the cupula (cupulolithiasis) within any of the three semicircular canals. Typical symptoms and signs of BPPV are evoked when the head is positioned so that the plane of the affected semicircular canal is spatially vertical and thus aligned with gravity. Paroxysm of vertigo and nystagmus develops after a brief latency during the Dix-Hallpike maneuver in posterior-canal BPPV, and during the supine roll test in horizontal-canal BPPV. Positioning the head in the opposite direction usually reverses the direction of the nystagmus. The duration, frequency, and symptom intensity of BPPV vary depending on the involved canals and the location of otolithic debris. Spontaneous recovery may be expected even with conservative treatments. However, canalithrepositioning maneuvers usually provide an immediate resolution of symptoms by clearing the canaliths from the semicircular canal into the vestibule.
    Full-text · Article · Jun 2010
    • "Several experimental models of cupulolithiasis and canalithiasis have been developed. Experiments with an in vitro frog model showed that otoconia placed on the cupula or in the semicircular canal, or dislodged from the utricle in a whole labyrinth, elicited different patterns of nerve excitation678. An experiment with an in vivo model in oyster toadfish, using glass microspheres the size of otoconia, showed changes in the firing rate of the vestibular nerve consistent with canalithiasis [9]. "
    [Show abstract] [Hide abstract] ABSTRACT: Although computational models suggest the existence of canalithiasis and cupulolithiasis subtypes of benign paroxysmal positional vertigo (BPPV), these subtypes cannot be distinguished from each other based on characteristics of nystagmus. Therefore, although the subtypes probably exist more information is needed from each patient than is available without invasive procedures. Also, some patients may have clinical syndromes that include both canalithiasis and cupulolithiasis subtypes. To determine if the parameters of nystagmus provide sufficient information to determine the subtype of nystagmus in a patient with BPPV. Patients (n = 118) had unilateral BPPV of the posterior canal; 15 patients also had BPPV of the lateral canal. The main outcome measures were parameters of nystagmus in response to the Dix-Hallpike maneuver: latency to onset of nystagmus, maximum slow phase velocity, and maximum duration. Correlations between pairs of variables showed minimal or no relationships. Also, cluster analyses showed no significant subtypes. The contralateral eye moved significantly faster than the ipsilateral eye.
    Full-text · Article · Mar 2010
    • "These responses, known as canalithiasis, are typically attributed to the movement of free-floating particles within the lumen of the membranous labyrinth [8,12,24]. Although the origins of either type of BPPV are not known, clinical evidence indicates that they may arise in a majority of cases as the result of head trauma [1,22]. Otoconia metabolism [17,21,29] and inner ear disorders (i.e. "
    [Show abstract] [Hide abstract] ABSTRACT: Horizontal canal (HC) benign paroxysmal positional vertigo (HC-BPPV) is a vestibular disorder characterized by bouts of horizontal ocular nystagmus induced during reorientation of the head relative to gravity. The present report addresses the application of a morphologically descriptive 3-canal biomechanical model of the human membranous labyrinth to study gravity-dependent semicircular canal responses during this condition. The model estimates dynamic cupular and endolymph displacements elicited during HC-BPPV provocative diagnostic maneuvers and canalith repositioning procedures (CRPs). The activation latencies in response to an HC-BPPV provocative diagnostic test were predicted to vary depending upon the initial location of the canalith debris (e.g. within the HC lumen vs. in the ampulla). Results may explain why the onset latency of ocular nystagmus evoked by the Dix-Hallpike provocative maneuver for posterior canal BPPV are typically longer than the latencies evoked by analogous tests for HC-BPPV. The model was further applied to assess the efficacy of a 360 degrees -rotation CRP for the treatment of canalithiasis HC-BPPV.
    Full-text · Article · Feb 2005
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