Munetaka Ushio

The ocular vestibular-evoked myogenic potential to air-conducted sound; probable superior vestibular nerve origin

OBJECTIVE Intense air-conducted sound (ACS) elicits an ocular vestibular-evoked myogenic potential (oVEMP), and it has been suggested that it does so by stimulating saccular receptors and afferents in the inferior vestibular nerve and so activating a crossed sacculo-ocular pathway. Bone conducted vibration (BCV) also elicits an oVEMP probably by activating utricular receptors and a crossed utriculo-ocular pathway. Are there two separate pathways mediating oVEMPs for ACS and BCV? If saccular receptors and afferents are primarily responsible for the oVEMP to ACS, then the oVEMP to ACS should be normal in patients with reduced or absent utricular function--unilateral superior vestibular neuritis (SVN). If utricular receptors and afferents are primarily responsible for oVEMP n10, then oVEMP to ACS should be reduced or absent in SVN patients, and in these patients there should be a close relationship between the size of the oVEMP n10 to BCV and to ACS. METHODS The n10 component of the oVEMP to 500 Hz BCV and to 500 Hz ACS was recorded in 10 patients with unilateral SVN but who had saccular and inferior vestibular nerve function preserved, as shown by their normal cVEMP responses to ACS. RESULTS In SVN patients with normal saccular and inferior vestibular nerve function, the oVEMP n10 in response to ACS was reduced or absent. Across SVN patients there was a very close correspondence between the size of oVEMP n10 for ACS and for BCV. CONCLUSIONS The n10 component of the oVEMP to ACS is probably mediated predominantly by the superior vestibular nerve and so most likely by utricular receptors and afferents. SIGNIFICANCE The n10 component of the oVEMP to either ACS or BCV probably indicates mainly superior vestibular nerve function.

Assessment of diagnostic accuracy of foam posturography for peripheral vestibular disorders: analysis of parameters related to visual and somatosensory dependence.

OBJECTIVES Simple tests to detect peripheral vestibulopathy might be practically useful before conducting elaborate examinations. The purpose of this study was to assess the diagnostic accuracy of foam posturography for peripheral vestibulopathy, with emphasis on visual and somatosensory dependence. METHODS Two-legged stance tasks were conducted in patients with unilateral (n=68) and bilateral (n=16) vestibulopathy and healthy controls (n=66), under four conditions; eyes open with and without the foam rubber, and eyes closed with and without the foam rubber. RESULTS The values of six parameters; the velocity of movement of the center of pressure (COP) and envelopment area tracing by the movement of the COP in eyes closed/foam rubber, the Rombergs ratios of velocity and area with foam rubber, and the foam ratios (ratios of a measured parameter with to without the foam rubber), of velocity and area in eyes closed, were significantly higher in unilateral and bilateral vestibulopathy compared with the control (p<0.001). The area under the receiver operating characteristic curve for the Rombergs ratio of velocity with the foam rubber was the largest. CONCLUSIONS Foam posturography detected high levels of visual and somatosensory dependence in patients with vestibulopathy. SIGNIFICANCE Foam posturography is useful for preliminary assessment of possible peripheral vestibulopathy.

Ocular vestibular-evoked myogenic potentials (oVEMPs) require extraocular muscles but not facial or cochlear nerve activity

OBJECTIVES Cervical vestibular evoked myogenic potentials (cVEMPs) have been found to be useful for clinical testing of vestibular function. Recently, investigators showed that short-latency, initially negative surface EMG potentials can be recorded around the extraocular muscles (oVEMPs) in response to air-conducted sound (ACS), bone-conducted vibration (BCV), and head taps. Although these evoked potentials, which are located around the eyes, most likely originate primarily from the otolith-ocular pathway, the possibility of contamination by other nerve activities cannot be completely eliminated. The purpose of the present study was to clarify the origin of oVEMPs by examining these possibilities using clinical findings. METHODS Twelve healthy subjects and 15 patients were enrolled. Of the 15 patients, 3 patients had undergone exenteration of the unilateral intraorbital contents, one had undergone exenteration of the right eyeball with preservation of extraocular muscles, 5 had facial palsy, and 6 had profound hearing loss. ACS and/or BCV were used in these subjects. RESULTS Exenteration of the unilateral intraorbital contents resulted in absence of myogenic potentials on the affected side. On the other hand, exenteration of the eyeball with preservation of extraocular muscles did not have a major impact on the responses. There were no significant differences in the waveforms between healthy subjects and patients with facial palsy or profound hearing loss. CONCLUSIONS The results suggested that short-latency, initially negative evoked potentials recorded below the eyes are not affected by cochlear or facial nerve activities and are dependent on the presence of extraocular muscles. SIGNIFICANCE This study provides the evidence that oVEMPs originate from exraocular muscles activated through the vestibulo-ocular pathway.

Age-related changes in cell dynamics of the postnatal mouse olfactory neuroepithelium: Cell proliferation, neuronal differentiation, and cell death

Age‐related changes in cell proliferation, neuronal differentiation, and cell death in mouse olfactory neuroepithelium were investigated. Mice at the age of 10 days through 16 months were given a single injection of bromodeoxyuridine (BrdU). The olfactory mucosae were fixed at 9 timepoints ranging from 2 hours to 3 months after the injection and examined using double immunostaining for BrdU and olfactory marker protein (OMP), and double staining with terminal deoxynucleotidyl transferase‐mediated biotinylated dUTP nick end labeling (TUNEL) and immunostaining for OMP. The number of BrdU‐labeled cells/mm epithelial length initially increased, peaked at 2–3 days after the BrdU injection, then declined at each age. The number of BrdU‐ and TUNEL‐labeled neuronal cells both decreased with increasing age, suggesting that the rates of both cell proliferation and cell death in the olfactory neuroepithelium decrease with increasing age. Double‐labeled cells for BrdU and OMP appeared at 7 days after injection in all age groups, suggesting that the time required for neuronal differentiation is broadly similar irrespective of age. In older age groups, smaller amounts of the newly produced cohort are integrated into the OMP‐positive ORN population, and even once it is integrated it is eliminated from the population more rapidly compared to the younger age groups. Furthermore, TUNEL assay showed that the fraction of apoptotic cells distributed in the OMP‐positive layer/total apoptotic cells decreased with age. This observation suggests that the turnover of mature ORNs is slower in the older neuroepithelium compared to the younger neuroepithelium. J. Comp. Neurol. 518:1962–1975, 2010.

Expression of IL‐33 and its receptor ST2 in chronic rhinosinusitis with nasal polyps

Interleukin (IL)−33 is a novel member of the IL‐1 cytokine family and a ligand for the orphan IL‐1 family receptor ST2. IL‐33 induces T helper 2‐type inflammatory responses and is considered to play a crucial role in allergic inflammatory reactions such as asthma and atopic dermatitis. However, the role of IL‐33 and its receptor ST2 in chronic rhinosinusitis remains unclear.

Frequency tuning properties of ocular vestibular evoked myogenic potentials

Loud air-conducted sound or bone-conducted vibration produces vestibular-dependent electromyographic responses both in the cervical muscles (cervical vestibular evoked myogenic potentials) and in the extraocular muscles (ocular vestibular evoked myogenic potentials; oVEMPs). Although previous frequency tuning measurements of cervical vestibular evoked myogenic potentials have provided important information for a clinical application, those of oVEMPs have rarely been studied. We explored the frequency tuning properties of oVEMPs in 12 healthy participants. Our results indicate that the best frequencies of the oVEMPs to air-conducted sound and bone-conducted vibration are 500 and 250 Hz, respectively. The difference in the best frequencies between the two stimuli may originate from the difference in the end organs (saccule or utricle), preferentially activated by each stimulus.

Recovery of vestibular evoked myogenic potentials after a vertigo attack due to vestibular neuritis

Conclusions. Inferior vestibular nerve functions could recover in patients with vestibular neuritis (VN). Objectives. Although the recovery of superior vestibular nerve functions has been reported, there is little information about the recovery of inferior vestibular nerve functions in patients with VN. This study was done to clarify if inferior vestibular nerve functions recover after an attack of VN. Methods. Neuro-otological tests including vestibular evoked myogenic potential (VEMP) testing and caloric testing were sequentially performed in 13 patients with VN, who showed absence of VEMP on the affected side at the initial examination (7 men and 6 women, 28–82 years of age). VEMPs to click stimulation (95 dBnHL) were recorded with surface electrodes over each sternocleidomastoid muscle. Results. Among the 13 patients, 5 patients (4 men and 1 woman) showed recovery of VEMP responses. Four of the five patients (three men and one woman) showed recovery of VEMP to the normal range. It takes 6 months to 2 years to recover within the normal range. On the other hand, caloric responses recovered to the normal range only in one patient.

Age‐related changes of the regeneration mode in the mouse peripheral olfactory system following olfactotoxic drug methimazole‐induced damage

We investigated age‐related changes in the mode of regeneration in the mouse peripheral olfactory system after olfactotoxic drug‐induced damage. Mice at postnatal ages of 10 days, 3 months, and 16 months were given an intraperitoneal injection of methimazole to produce damage in the olfactory neuroepithelium. The olfactory neuroepithelia were harvested and analyzed immunohistochemically at various postlesion timepoints, from 1 day through to 94 days, to investigate neuroepithelial cell proliferation, the time course of neuronal differentiation, the reconstitution of neuroepithelium, and the innervation of the olfactory bulb. Functional recovery was assessed using the vanillin avoidance behavioral test. The chronological pattern in the expression of Ki67, beta III tubulin, and olfactory marker protein, molecular markers for neuronal cell proliferation and differentiation, changed similarly among the different age groups. In contrast, the extent of neuroepithelial cell proliferation after injury decreased with age, and the final histological recovery of the olfactory neuroepithelium and the innervation of the olfactory bulb were significantly smaller in the 16‐month‐old group compared to the younger age groups. These results suggest that the age‐related decline in the capacity of olfactory neuroepithelium to reconstitute neuroepithelium is associated with its age‐related decrease in proliferative activity after the neuroepithelial injury rather than changes in the process of neuronal differentiation. In spite of these incomplete anatomical recoveries, 16‐month‐old mice regained the ability to avoid vanillin solution by 1 month postlesion, suggesting that the extent of anatomical epithelial damage is not necessarily proportional to the threshold of olfactory perception. J. Comp. Neurol. 519:2154–2174, 2011.

Effect of vestibular dysfunction on the development of gross motor function in children with profound hearing loss.

Objective: To evaluate the function of the superior and inferior vestibular nerve systems in children with profound sensorineural hearing loss, and to assess the influence of dysfunction of each vestibular nerve system on the development of gross motor function. Study Design: Retrospective study. Setting: A tertiary referral center. Methods: Eighty-nine children (age range: 20–97 months) with profound sensorineural hearing loss who were due to undergo cochlear implant surgery were recruited. Function of the superior vestibular nerve system was evaluated by the damped rotation test and the caloric test, whereas functions of the inferior vestibular nerve systems were evaluated by the vestibular evoked myogenic potential (VEMP) test. Gross motor development was assessed using the age of acquisition of head control and independent walking. Results: Among the children able to complete the vestibular function tests, abnormalities were found in 20% (16 of 84 children) in the damped rotation test, 41% (31 of 75 children) in the caloric test and 42% (26 of 62 children) in the VEMP test. Children who showed abnormal responses in the vestibular function tests showed significantly delayed acquisition of head control (p < 0.05) and independent walking (p < 0.05) in comparison with children with normal responses. The children who showed abnormal responses in all 3 vestibular tests showed the greatest delay in acquisition of gross motor function in comparison with the other groups. Conclusions: Children with profound hearing loss tend to have dysfunction in the superior as well as the inferior vestibular nerve systems. Both the superior and inferior vestibular nerve systems are important for the development of gross motor function in children.

Ocular vestibular evoked myogenic potentials to bone-conducted vibration in vestibular schwannomas.

Background: Vestibular schwannoma (VS) arises from either the superior or the inferior vestibular nerve and causes vestibular dysfunction to various degrees. Recently, ocular vestibular evoked myogenic potentials to bone-conducted vibration (oVEMPs to BCV) have attracted much interest as a new clinical test for otolith-ocular pathway function. Because it is unclear whether the oVEMPs to BCV primarily originate from activation of the superior or the inferior vestibular nerve, the results in patients with VS might enlighten us concerning the origin of oVEMPs to BCV. Objective: To compare the results of 3 clinical tests for vestibular function in patients with VS: 1) oVEMPs to BCV; 2) cervical vestibular evoked myogenic potentials to air-conducted sound (cVEMPs to ACS), which reflect the function of inferior vestibular nerve; and 3) caloric test, which reflect the function of superior vestibular nerve. Methods: Thirty-six patients with unilateral VS who underwent vestibular tests, including oVEMPs to BCV, cVEMPs to ACS, and caloric tests, were enrolled. The asymmetry ratios of the amplitudes of the oVEMPs to BCV and cVEMPs to ACS and canal paresis on the caloric test were measured. Results: Among the 36 patients with VS, 31 (86%) showed reduced or absent oVEMPs to BCV. Twenty-eight patients (78%) showed abnormal cVEMPs to ACS, and 31 (86%) showed abnormal caloric responses. The consistency of the results between oVEMPs to BCV and the caloric test was significantly higher than that between oVEMPs to BCV and cVEMPs to ACS (p < 0.02). Conclusion: Ocular vestibular evoked myogenic potentials to bone-conducted vibration mainly reflect the function of the superior vestibular nerve.