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Vestibular evoked myogenic potential (VEMP) in response to a loud air conducted sound (ACS) recorded from extraocular muscles, the so-called ocular VEMP (oVEMP), has been confirmed to be able to evaluate utricular function. This study aimed to evaluate the effect of sleep deprivation (SD) on oVEMP parameters. oVEMPs were recorded in 20 male healthy subjects once after an ordinary sleep and once after 26–29 h of SD. The latencies of peak N1 and P1, N1-P1 amplitude, N1-P1 interval, and asymmetry ratio (AR) of oVEMP recorded from both eyes under normal sleep and SD conditions were 10.04 ± 0.59 ms versus 10.56 ± 0.69 ms (left eye), 14.95 ± 0.92 ms versus 15.64 ± 1.05 ms (left eye), and 7.44 ± 2.86 µV versus 5.26 ± 2.15 µV (left eye); 10.08 ± 0.66 ms versus 10.64 ± 0.73 ms (right eye), 14.88 ± 0.89 ms versus 15.59 ± 1.02 ms (right eye), and 7.16 ± 2.88 µV versus 5.04 ± 2.05 µV(right eye); 10.40 ± 5.81% versus 11.43 ± 6.37%, respectively. After SD, the latencies of oVEMP were delayed and N1-P1 amplitude was lower, whereas N1-P1 interval and AR remained unchanged. The present study showed that oVEMP test could be used to evaluate the fatigue induced by SD.

Spatial disorientation in airplane pilots is a leading factor in many fatal flying accidents. Spatial orientation is the product of integrative inputs from the proprioceptive, vestibular, and visual systems. One condition that can lead to sudden pilot incapacitation in fight is vestibular neuritis. Vestibular neuritis is commonly diagnosed by a finding of unilateral vestibular failure, such as a loss of caloric response. However, because caloric response testing reflects the function of only the superior part of the vestibular nerve, it cannot detect cases of neuritis in only the inferior part of the nerve. We describe the case of a Chinese naval command fighter pilot who exhibited symptoms suggestive of vestibular neuritis but whose caloric response test results were normal. Further testing showed a unilateral loss of vestibular evoked myogenic potentials (VEMPs). We believe that this pilot had pure inferior nerve vestibular neuritis. VEMP testing plays a major role in the diagnosis of inferior nerve vestibular neuritis in pilots. We also discuss this issue in terms of aeromedical concerns.

BACKGROUND A functional vestibular system is a prerequisite for motion sickness (MS) to occur. The otolithic organs (saccule and utricle) are currently considered to be important in the pathogenesis of MS. Recent investigations have demonstrated that the ocular vestibular evoked myogenic potentials (oVEMP) test is an objective evaluation of utricular function. To date, there is no functional guide that can serve as a diagnostic tool for individual susceptibility to MS. Therefore, we investigated the link between oVEMP and MS susceptibility. METHOD The oVEMP test was performed on 31 MS susceptible and 23 nonsusceptible individuals. MS susceptibility was determined by self-declaration and by using the MS susceptibility questionnaire (MSSQ) and the Hamilton Anxiety Scale (HAS). RESULTS Bilateral oVEMP responses were obtained in all subjects. HAS and MSSQ scores between the susceptible and nonsusceptible group were 18.27 +/- 5.23 vs. 2.34 +/- 1.21 and 28.12 +/- 6.53 vs. 2.34 +/- 1.45, respectively. Statistically significant differences in MSSQ and HAS scores were found between the MS susceptible and nonsusceptible groups. No differences were found between MS susceptible and nonsusceptible subjects in N10 and P15 wave latencies, N10-P15 interval, or peak-to-peak N10-P15 amplitude. However, there was a trend toward greater asymmetry ratio in the MS susceptible group than in the MS nonsusceptible group (18.55 +/- 10.24% vs. 13.25 +/- 9.47%), although statistical significance was not reached. DISCUSSION It appears that no relation exists between oVEMP results and MS susceptibility. Nevertheless, the differences in the asymmetry ratios of oVEMP interpeak amplitude between the two groups revealed a trend toward marginal statistical significance.

INTRODUCTION Excellent vestibular function (including utricular function) is important for pilots to maintain correct spatial orientation during flight. Vestibular-evoked myogenic potential (VEMP) recorded from extraocular muscles, the so-called ocular VEMP (oVEMP), can be used to evaluate utricular function. However, oVEMP has not been applied to pilots because of lack of reliable normative data. Hence, this study is designed to establish preliminary normative data for oVEMP induced by air-conducted sound in pilots and student pilots. METHODS There were 62 healthy student pilots (30 male and 32 age-matched female) and 31 healthy male fighter pilots who were recruited as study participants. During binaural air-conducted sound stimulation oVEMP was recorded bilaterally. The latencies of nI and pI, nI-pI interval, peak-to-peak nI-pI amplitude, and asymmetry ratio (AR) of oVEMP in all participants were collected. Meanwhile, the effects of gender and age on oVEMP were also investigated. RESULTS The latencies of nI and pI, nI-pI interval, nI-pI interpeak amplitude, and AR of oVEMP in all participants were 10.35 +/- 0.66 ms, 15.18 +/- 1.07 ms, 4.75 +/- 0.99 ms, 6.75 +/- 4.13 microV, and 13.22 +/- 9.13%, respectively. No significant difference existed between male student pilots and male pilots in terms of oVEMP parameters. The only significant difference was the nI-pI amplitude between age-matched male and female student pilots: 6.96 +/- 3.85 microV for male student pilots and 5.47 +/- 3.10 microV for female student pilots. CONCLUSIONS oVEMP should be interpreted with the AR rather than raw amplitude itself. Each institution should determine its own normal values.

Background Effects of high Gz acceleration can threaten flight safety through loss of consciousness or a lesser-known phenomenon, G-induced vestibular dysfunction (GIVD). There are reports of GIVD following high-G flight or centrifuge exposure. The aim of this study was to explore this problem under controlled conditions using a human centrifuge. Methods There were 11 pilots who were exposed to +9 Gz for 10 s. Measurements were made before and after G exposure to assess vestibular function, including spontaneous nystagmus, positioning nystagmus, optokinetic nystagmus, vestibular ocular reflex, vestibular-vision interaction, subjective vision vertical perception, and vestibular-evoked myogenic potentials. Results No significant change was found for vestibular function after the Gz exposure. Conclusion It appears +9 Gz for 10 s does not produce GIVD. However, the possible effects of prolonged high G maneuvers in modern aircraft combined with head movements may warrant further study.

We were pleased to read the review presented by Eleftheriadou et al. [1], which has been published in Eur Arch Otorhinolaryngol 268(3):331–339, 2011. This review is an excellent practice guide to understand vestibular evoked myogenic potentials. However, I would like to point out two errors in this review. The first error is in the section ‘‘Effect of electrode location on the SCM muscle and responses from the other muscles’’ paragraph 2 line 3, ‘‘...smaller myogenic response (n11–n15) can be recorded over...’’, in which ‘‘n11–n15’’ should be modified as ‘‘p11–n15’’ according to Deriu et al. [2]. The second error is in the section ‘‘Ocular VEMP’’ paragraph 4 line 8, ‘‘...is predominantly determined by saccular activation.’’, in which ‘‘saccular’’ should be modified as ‘‘utricular’’. In my opinion, these typographical errors should be corrected since these errors may baffle and misguide the general reader.

We were pleased to read the report presented by Manzari et al. [1], which has been published in Eur Arch Otorhinolaryngol, 2010, 267(9):1487–1489. They described an unusual patient with reduced inferior vestibular nerve function who provides the complementary but converse evidence for these suggestions by showing reduced cVEMP potentials but normal oVEMPs for both ACS and BCV stimuli, this case report provides further evidence that the origin of oVEMP in response to ACS is the utricle macula [2]. However, I would like to point to one error in Figure 1. In Figure 1 illustration, the authors described ‘‘The strong asymmetry amplitude of the p13–n23 complex between left (normal side) and right (affected side) in cVEMPs is evident (a).’’ The authors confused the direction of the pathology since the patient were diagnosed as having left inferior vestibular neuritis. So the right description is ‘‘The strong asymmetry amplitude of the p13–n23 complex between right (normal side) and left (affected side) in cVEMPs is evident (a).’’ This rectification is important since the description in Figure 1 illustration may baffle the readers.