Interface and bulk rheologies of soft solid pastes

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Masseter Vestibular evoked myogenic potentials: A new tool to assess the vestibulomasseteric reflex pathway

Purpose: This review article provides the readers with an in-depth insight in understanding and interpreting various research literatures on the masseter vestibular evoked myogenic potentials (mVEMP). The article also reviews the contemporary researches involving the clinical applications of the mVEMP. Conclusions: Masseter VEMP is an evolving yet clinically promising neuro-otology test tool that has recently gained more research interest and is considered an additional tool to diagnose various vestibular disorders. Masseter VEMP assesses the functional integrity of the acoustic-masseteric and vestibulo-masseteric reflex pathways. The mVEMP could be used as a complementary test to evaluate the same peripheral generator as the cervical VEMP but a different central pathway i.e., vestibulo-trigeminal pathway. Various research studies that have experimented on parameters such as the effect of different electrode montages (zygomatic vs mandibular configurations), stimulation rates, filter settings and stimuli used to evoke mVEMP have been discussed in this article that could assist in the optimization of a comprehensive clinical protocol. The latency and the amplitude of mVEMP waveforms serve as significant parameters in differentiating normals from those of the clinical populations. Along with the cVEMPs and oVEMPs, mVEMP might help diagnose brainstem lesions in REM Sleep behaviour disorders, Multiple Sclerosis and Parkinson's disease. However, further studies are required to probe in this area of research

Masseter vestibular-evoked myogenic potentials at different tone burst frequencies in healthy individuals

Abstract Background Masseter vestibular-evoked myogenic potentials (mVEMP) are vestibular-dependent inhibitory reflex recorded using acoustic stimulus. mVEMP can assess important brainstem regions. mVEMP abnormalities have been reported in patients with multiple sclerosis, Parkinson’s disease, and idiopathic random eye movement disorder. The objective of the study was to record mVEMP using tone-burst stimulus at different frequencies in young healthy individuals. Method The study used normative study design. Thirty-two participants, aged 18–28 years with normal hearing and balance function, were recruited for the study. Simple random sampling was used for selection of participants. Data collection and analysis mVEMP was recorded for all the individuals at 500 Hz,750 Hz,1000 Hz, 2000 Hz, and 4000 Hz tone burst stimuli. The p11 and n21 peaks were identified. The latency of the p11 and n21 peaks and the rectified amplitude of the p11-n21 peak complex were measured for all the participants. Wilcoxson signed-rank test was used for statistical anlysis. Results The study found a 100% response rate and higher amplitude for 500 Hz and 750 Hz tone burst stimuli. However, Wilcoxson signed-rank test with Bonferroni correction showed no significant difference in amplitude (p = 0.92) between 500 and 750 Hz. Conclusion The study recommends 500 Hz/750 Hz tone burst stimuli as an optimal frequency for recording mVEMP in young, healthy individuals. However, seeing the frequency-tuning characteristics of mVEMP in other peripheral vestibular pathologies would be interesting

Comparison of Cervical and Ocular Vestibular Evoked Myogenic Potentials in Dancers and Non-Dancers

The objective of the study was to assess the sacculocollic and otolith ocular pathway function using cervical vestibular evoked myogenic potentials (cVEMP) and ocular vestibular myogenic potentials (oVEMP) in dancers and non dancers. Total 16 subjects participated in the study. Out of 16 participants, 8 were trained in Indian classical form of dance (dancers) and other 8 participants who were not trained in any dance form (non dancers). cVEMP and oVEMP responses were recorded for all the subjects. Non Parametric Mann-Whitney U test revealed no significant difference between dancers and non dancers for the latency and amplitude parameter for cVEMP and oVEMP, i.e. P13, N23 latency and P13-N23 complex amplitude and N10, P14 latency, N10-P14 complex amplitude respectively. The vestibular system comprises of several structures. It is possible that the dance style practiced by the dancer’s group assessed in this study does not contribute towards improving the plasticity of the sacculocollic and otolith-ocular pathways. It can be concluded that not all forms of dance training brings about a change in the plasticity of the sacculocollic and otolithocular pathways

cVEMP, oVEMP and Caloric Test Results in Individuals with Meniere’s Disease

Objective: The present study aimed to characterize cVEMP, oVEMP and caloric test findings in individuals with Meniere’s disease.Methods: 29 participants with Meniere’s disease and 29 participants with normal hearing were enrolled for the study. Out of 29 participants in the experimental group, 25 of them had unilateral Meniere’s disease and 4 of them had bilateral Meniere’s disease (Total 33 ears diagnosed with Meniere’s and 25 ears with non-Meniere’s disease). All the participants underwent routine audiological, cVEMP, oVEMP and Caloric testing.Results: Out of 33 ears with Meniere’s disease, 29 ears had absent responses on cVEMP, 23 ears showed absent oVEMP responses, 27 ears had hypo-activity, five ears showed hyper activity and one ear showed normal response to caloric stimulation. In the contralateral ear (25 ears with non-Meniere’s disease) both cVEMP and oVEMP were absent in 5 of the ears, cVEMP was absent and oVEMP was present in 13 ears, cVEMP was present and oVEMP was absent in 1 ear, whereas both cVEMP and oVEMP were present in 6 ears in individuals with Meniere’s disease. However, the caloric responses were present normally in the contralateral ear in individuals with Meniere’s disease.Conclusions: The combination of cVEMP, oVEMP and caloric test provides valuable information regarding localization of hydrops in individuals with Meniere’s disease

Cervical and Ocular Vestibular Evoked Myogenic Potentials Test Results in Individuals with Auditory Neuropathy Spectrum Disorders

“Auditory neuropathy spectrum disorder” is a clinical disorder where the outer hair cell functioning is intact but the functioning of the auditory nerve is affected. Since, the 8th nerve is constituted by both the auditory and vestibular branch of nerve fibers, there are chances that the vestibular nerve might also be affected. Hence, the current study was carried out in order to determine the functioning of vestibular nerve in individuals with Auditory Neuropathy. A total of 11 participants were considered for the current study. cVEMPs and oVEMPs were administered using the conventional protocol. In all the participants (100%) the oVEMPs were absent whereas in 2 ears out of 22 ears tested (90.90%) the cVEMPs were absent. The results of the present study indicate a high incidence of vestibular involvement in individuals with auditory neuropathy spectrum disorders. Also, it necessitates the inclusion of vestibular tests in the test battery used to assess individuals with auditory neuropathy spectrum disorder

Cervical and ocular vestibular evoked myogenic potentials test results in individuals with auditory neuropathy spectrum disorders

“Auditory neuropathy spectrum disorder” is a clinical disorder where the outer hair cell functioning is intact but the functioning of the auditory nerve is affected. Since, the 8th nerve is constituted by both the auditory and vestibular branch of nerve fibers, there are chances that the vestibular nerve might also be affected. Hence, the current study was carried out in order to determine the functioning of vestibular nerve in individuals with Auditory Neuropathy. A total of 11 participants were considered for the current study. cVEMPs and oVEMPs were administered using the conventional protocol. In all the participants (100%) the oVEMPs were absent whereas in 2 ears out of 22 ears tested (90.90%) the cVEMPs were absent. The results of the present study indicate a high incidence of vestibular involvement in individuals with auditory neuropathy spectrum disorders. Also, it necessitates the inclusion of vestibular tests in the test battery used to assess individuals with auditory neuropathy spectrum disorder

Effect of repetition rate on speech evoked auditory brainstem response in younger and middle aged individuals

Speech evoked auditory brainstem responses depicts the neural encoding of speech at the level of brainstem. This study was designed to evaluate the neural encoding of speech at the brainstem in younger population and middle-aged population at three different repetition rates (6.9, 10.9 and 15.4). Speech evoked auditory brainstem response was recorded from 84 participants (young participants=42, middle aged participants=42) with normal hearing sensitivity. The latency of wave V and amplitude of the fundamental frequency, first formant frequency and second formant frequency was calculated. Results showed that the latency of wave V was prolonged for middle-aged individuals for all three-repetition rates compared to the younger participants. The results of the present study also revealed that there was no difference in encoding of fundamental frequency between middle aged and younger individuals at any of the repetition rates. However, increase in repetition rate did affect the encoding of the fundamental frequency in middle-aged individuals. The above results suggest a differential effect of repetition rate on wave V latency and encoding of fundamental frequency. Further, it was noticed that repetition rate did not affect the amplitude of first formant frequency or second formant frequency in middle aged participants compared to the younger participants