Hearing and Vestibular Testing in Menière’s Disease

Endolymphatic hydrops (ELH) known as the main pathophysiology of Menière’s disease (MD) changes both the cochlear and vestibular function of the inner ear. These physiological changes can occur simultaneously (cochleovestibular involvement) or separately (cochlear or vestibular involvement). They can also present unilaterally or bilaterally (simultaneously or sequentially). Moreover, ELH recurs periodically without any specific etiology and known rhythm. Therefore, the patient referred for audiological tests may be in attack phase (acute) or inter-attack phase (chronic). MD itself may be in early- or advanced stage. In addition, considering comorbidity (vestibular or non-vestibular) is vital for differential diagnosis. On the other hand, each audiological test (including PTA, ECochG, VNG, vHIT, SVV, VEMPs …) has its specific diagnostic viewpoint and gives us a limited snapshot of MD’s clinical picture. Consequently, in this chapter, we want to discuss these viewpoints and try to explain associations and dissociations of audiological test findings in MD patients

The effect of head tilt angle in the roll plane on the virtual subjective visual vertical results in healthy adults

Background and Aim: The subjective visual vertical (SVV) is commonly considered as an indicator of the sense of orientation and attributed to the utricular function. The present study examined the impact of different head tilt angles on SVV among the normal individuals. Methods: SVV was measured in 47 normal participants (30 males and 17 females; mean ± SD age: 22.14 ± 3.46) using a virtual goggle and forced-choice paradigm and was applied twice in 0º, 15º, 30° and 45º to the left or to the right. In addition, difference in mean of SVV in zero and non-zero positions was compared. Results: There was a statistically significant difference between the mean SVV results of 0º and 15º (p ˂ 0.001). The comparison of mean SVV results between 0º and 30º, and between 0º and 45º were not significant (p > 0.05). In addition, comparison of SVV results between rightward and leftward tilt of 15º was statistically significant (p ˂ 0.001). The latter comparison was not significant for 30º and 45º (p > 0.05). Conclusion: Our results showed that head tilt angle of 15º have a substantial impact on the virtual SVV. These findings must be taken into account in the growing body of research that uses the SVV paradigm in clinical populations

Mode of recording and modulation frequency effects of auditory steady state response thresholds

Abstract Introduction The performance of auditory steady state response (ASSR) in threshold testing when recorded ipsilaterally and contralaterally, as well as at low and high modulation frequencies (MFs), has not been systematically studied. Objective To verify the influences of mode of recording (ipsilateral vs. contralateral) and modulation frequency (40 Hz vs. 90 Hz) on ASSR thresholds. Methods Fifteen female and 14 male subjects (aged 18–30 years) with normal hearing bilaterally were studied. Narrow-band CE-chirp® stimuli (centerd at 500, 1000, 2000, and 4000 Hz) modulated at 40 and 90 Hz MFs were presented to the participants' right ear. The ASSR thresholds were then recorded at each test frequency in both ipsilateral and contralateral channels. Results Due to pronounced interaction effects between mode of recording and MF (p < 0.05 by two-way repeated measures ANOVA), mean ASSR thresholds were then compared among four conditions (ipsi-40 Hz, ipsi-90 Hz, contra-40 Hz, and contra-90 Hz) using one-way repeated measures ANOVA. At the 500 and 1000 Hz test frequencies, contra-40 Hz condition produced the lowest mean ASSR thresholds. In contrast, at high frequencies (2000 and 4000 Hz), ipsi-90 Hz condition revealed the lowest mean ASSR thresholds. At most test frequencies, contra-90 Hz produced the highest mean ASSR thresholds. Conclusions Based on the findings, the present study recommends two different protocols for an optimum threshold testing with ASSR, at least when testing young adults. This includes the use of contra-40 Hz recording mode due to its promising performance in hearing threshold estimation

Data on galvanic-evoked head movements in healthy and unilaterally labyrinthectomized rats

In this dataset, we analyzed galvanic-evoked head movements (GEHMs) in the spatial planes of yaw, and roll in normal and unilaterally labyrinthectomized (UL) Wistar rats. The rats were assigned in 4 groups of 10: control, sham, right-UL and left-UL. Bilateral galvanic vestibular stimulation (GVS) was presented by our “ring-shaped electrode” design (see “Short-term galvanic vestibular stimulation promotes functional recovery and neurogenesis in unilaterally labyrinthectomized rats” (M. Shaabani et al., 2016) [1]). Required data were collected through video recording of GEHMs followed by image processing and statistical analysis