Introduction:The masseter vestibular evoked myogenic potential(mVEMP)is a bilaterally generated,electromyographically(EMG)-mediated response innervated by the trigeminal nerve.The purpose of the present investigation ...Introduction:The masseter vestibular evoked myogenic potential(mVEMP)is a bilaterally generated,electromyographically(EMG)-mediated response innervated by the trigeminal nerve.The purpose of the present investigation was to 1)determine whether subjects could accurately achieve and maintain a range of EMG target levels,2)to examine the effects of varied EMG levels on the latencies and amplitudes of the mVEMP,and 3)to investigate the degree of side-to-side asymmetry and any effects of EMG activation.Methods:Subjects were nine neurologically and otologically normal young adults.A high-intensity tone burst was presented monaurally while subjects were seated upright and asked to match a range of EMG target levels by clenching their teeth.Recordings were made from the ipsilateral and contralateral masseter muscles referenced to the ear being monaurally stimulated.Results:We found that the tonic EMG target had no effect on mVEMP latency.Additionally,although mVEMP amplitudes“scaled”to the EMG target,there was a tendency for the subjects’EMG level to“undershoot”the EMG target levels greater than 50 mV.While some individuals did generate differences in EMG activation between sides,there were no significant differences on average EMG activation between sides.Further,while average corrected amplitude asymmetry was similar across EMG targets,some individuals demonstrated large,corrected amplitude asymmetry ratios.Conclusions:The results of this investigation suggest that,as with cVEMP recordings,the underlying EMG activation may vary between subjects and could impact mVEMP amplitudes,yet could be mitigated by amplitude correction techniques.Further it is important to be aware that even young normal subjects have difficulty maintaining large,tonic EMG activity during the mVEMP recording.展开更多
Pilot spatial disorientation is a leading factor contributing to many fatal flying accidents. Spatial orientation is the product of integrative inputs from the proprioceptive, vestibular, and visual systems. Vestibula...Pilot spatial disorientation is a leading factor contributing to many fatal flying accidents. Spatial orientation is the product of integrative inputs from the proprioceptive, vestibular, and visual systems. Vestibular neuritis (VN) can lead to sudden pilot incapacitation in flight. VN is commonly diagnosed by demonstration of unilateral vestibular failure, as unilateral loss of caloric response. As this test reflects the function of the superior part of the vestibular nerve only, cases of pure inferior nerve neuritis will be lost. This paper describes a fighter pilot with symptoms suggestive of VN but with normal caloric test results. Further test showed unilateral loss of vestibular evoked myogenic potential. We believe that the pilot suffered from pure inferior nerve vestibular neuritis. VEMP plays a major role in the diagnosis of inferior nerve vestibular neuritis in pilots. Aeromedical concerns are also discussed.展开更多
Profound sensorineural hearing loss (PSHL) is not uncommonly encountered in otology. In clinics, there is a high incidence of otolithic damage in patients with PSHL, but relevant reports are few. Sharing a continuous ...Profound sensorineural hearing loss (PSHL) is not uncommonly encountered in otology. In clinics, there is a high incidence of otolithic damage in patients with PSHL, but relevant reports are few. Sharing a continuous membranous structure and similar receptor cell ultrastructures, the cochlea and vestibule may be susceptible to the same harmful factors. Disorders of the inner ear may result in a variety of manifestations, including vertigo, spatial disorientation, blurred vision, impaired articulation, and hearing impairment. Considering the diversity of clinical symptoms associated with PSHL with otolithic dysfunction, it may be frequently misdiagnosed, and objective means of testing the function of otolithic organs should be recommended for hearing-impaired patients. Vestibular-evoked myogenic potentials (VEMPs) via air-conducted sound are of great importance for the diagnosis of otolithic function. Hearing devices such as cochlear implants are commonly accepted treatments for PSHL, and early identification and treatment of vestibular disorders may increase the success rate of cochlear implantation. Therefore, it is necessary to increase awareness of otolithic functional states in patients with PSHL.展开更多
文摘Introduction:The masseter vestibular evoked myogenic potential(mVEMP)is a bilaterally generated,electromyographically(EMG)-mediated response innervated by the trigeminal nerve.The purpose of the present investigation was to 1)determine whether subjects could accurately achieve and maintain a range of EMG target levels,2)to examine the effects of varied EMG levels on the latencies and amplitudes of the mVEMP,and 3)to investigate the degree of side-to-side asymmetry and any effects of EMG activation.Methods:Subjects were nine neurologically and otologically normal young adults.A high-intensity tone burst was presented monaurally while subjects were seated upright and asked to match a range of EMG target levels by clenching their teeth.Recordings were made from the ipsilateral and contralateral masseter muscles referenced to the ear being monaurally stimulated.Results:We found that the tonic EMG target had no effect on mVEMP latency.Additionally,although mVEMP amplitudes“scaled”to the EMG target,there was a tendency for the subjects’EMG level to“undershoot”the EMG target levels greater than 50 mV.While some individuals did generate differences in EMG activation between sides,there were no significant differences on average EMG activation between sides.Further,while average corrected amplitude asymmetry was similar across EMG targets,some individuals demonstrated large,corrected amplitude asymmetry ratios.Conclusions:The results of this investigation suggest that,as with cVEMP recordings,the underlying EMG activation may vary between subjects and could impact mVEMP amplitudes,yet could be mitigated by amplitude correction techniques.Further it is important to be aware that even young normal subjects have difficulty maintaining large,tonic EMG activity during the mVEMP recording.
基金supported by the National Natural Science Foundation of China (Grant No. 30871220)
文摘Pilot spatial disorientation is a leading factor contributing to many fatal flying accidents. Spatial orientation is the product of integrative inputs from the proprioceptive, vestibular, and visual systems. Vestibular neuritis (VN) can lead to sudden pilot incapacitation in flight. VN is commonly diagnosed by demonstration of unilateral vestibular failure, as unilateral loss of caloric response. As this test reflects the function of the superior part of the vestibular nerve only, cases of pure inferior nerve neuritis will be lost. This paper describes a fighter pilot with symptoms suggestive of VN but with normal caloric test results. Further test showed unilateral loss of vestibular evoked myogenic potential. We believe that the pilot suffered from pure inferior nerve vestibular neuritis. VEMP plays a major role in the diagnosis of inferior nerve vestibular neuritis in pilots. Aeromedical concerns are also discussed.
文摘Profound sensorineural hearing loss (PSHL) is not uncommonly encountered in otology. In clinics, there is a high incidence of otolithic damage in patients with PSHL, but relevant reports are few. Sharing a continuous membranous structure and similar receptor cell ultrastructures, the cochlea and vestibule may be susceptible to the same harmful factors. Disorders of the inner ear may result in a variety of manifestations, including vertigo, spatial disorientation, blurred vision, impaired articulation, and hearing impairment. Considering the diversity of clinical symptoms associated with PSHL with otolithic dysfunction, it may be frequently misdiagnosed, and objective means of testing the function of otolithic organs should be recommended for hearing-impaired patients. Vestibular-evoked myogenic potentials (VEMPs) via air-conducted sound are of great importance for the diagnosis of otolithic function. Hearing devices such as cochlear implants are commonly accepted treatments for PSHL, and early identification and treatment of vestibular disorders may increase the success rate of cochlear implantation. Therefore, it is necessary to increase awareness of otolithic functional states in patients with PSHL.
