Benign paroxysmal positional vertigo (BPPV) constitutes a major proportion of the population with peripheral vestibulopathies. Although the freely floating otoconia within the semicircular canals is responsible for the symptoms of BPPV, the source of the otoconia debris is mainly believed to be the otolith organs. Therefore, the pathology in either or both the otolith organs appears a logical proposition. Cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP), being the tests for functional integrity of the otolith organs, appear promising for investigating otolith involvement in BPPV. While recent evidences are suggestive of equivocal findings for cVEMP, there are only a few studies on oVEMP. Additionally, both these potentials have never been explored in the same set of individuals with BPPV. Therefore, the present study aimed to evaluate the functional integrity of the otolith organs through cVEMP and oVEMP in individuals with posterior canal BPPV. Thirty-one individuals with unilateral posterior canal BPPV and 31 age- and gender-matched healthy controls underwent 500 Hz tone-burst-evoked cVEMP and oVEMP. The results demonstrated no significant group difference on any of the cVEMP parameters (p > 0.05). A similar trend was noticed for the latency-related parameters of oVEMP. However, the peak-to-peak amplitude was significantly smaller in the affected ears of individuals with BPPV than their unaffected ears and the ears of healthy controls (p < 0.05). The BPPV group showed significantly higher inter-aural amplitude difference ratio than the healthy controls (p < 0.05). Further, the sensitivity and specificity of oVEMP were also found to be far superior to those of cVEMP. Thus, the outcome of the present study revealed involvement of utricle rather than saccule in posterior canal BPPV, and therefore, oVEMP appears to be better suited to clinical investigation than cVEMP in individuals with posterior canal BPPV.
BACKGROUND: Cervical vestibular evoked myogenic potential (cVEMP) is a biphasic potential recorded from the Sternocleidomastoid muscle in response to loud acoustic stimulation and assesses the intactness of the Sacculocolic pathway. The literature on clinical utility of cVEMP has been growing rapidly, though not without inconsistencies despite involving alike population. A close scrutiny of the methods across such studies revealed an inconsistent use of stimulus parameters; especially rise/fall times (RFTs). However the effect of RFTs on cVEMP has been largely unexplored. OBJECTIVE: The study aimed at exploring the effect of varying RFTs on cVEMP and obtaining optimum RFT to enable reliable recording of cVEMPs. METHODS: The cVEMPs were recorded from both ears of 30 healthy individuals with normal audio-vestibular system using 500 Hz short tone-bursts (STBs) at 95 dB nHL and varying the RFTs from 1 to 8 ms at all integer values. RESULTS: There was significant prolongation of latencies with increasing RFTs (p < 0.05). The largest amplitudes were obtained for 2 to 3 ms RFTs, though significantly smaller amplitude was obtained only for 8 ms RFT (p < 0.05), thereby rendering 8 ms RFT unfit for cVEMP recording. The 1 ms RFT produced smallest variability across individuals and would also result in lesser duration of exposure to loud sound. CONCLUSIONS: The RFT of 1 ms of 500 Hz STBs are optimum for recording cVEMPs. This is owing to large amplitudes and least variability demonstrated for this RFT.
Introduction Diabetes mellitus is a metabolic disease associated with a rise in the level of blood glucose. Individuals with diabetes mellitus are more likely to develop hearing loss, tinnitus, and dizziness due to macro- and microvascular complications. The extent to which auditory and vestibular functions are impaired in individuals with type-2 diabetes mellitus is still under debate.
Objective To systematically review studies focusing on auditory and vestibular functions in individuals with type-2 diabetes mellitus.
Data Synthesis A search was conducted in the PubMed, MedlinePlus, Ingenta Connect and Google Scholar databases for articles published until June 2019. A total of 15,980 articles were primarily retrieved, 33 of which were shortlisted based on the inclusion criteria set by the investigators for the systematic review. Out of 33 full-length articles, 26 evaluated the functioning of the auditory system, while 7 evaluated the functioning of the vestibular system. Most studies related to auditory functioning reported a significant effect of type-2 diabetes mellitus on the peripheral auditory system, whereas studies on vestibular functioning reported no significant effect of diabetes mellitus on the functioning of the peripheral vestibular end-organ.
Conclusion Overall, the results of various audiological and peripheral vestibular tests reveal distinctive peripheral and/or central auditory and vestibular end-organ impairments in individuals with type-2 diabetes mellitus.
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