Affiliations: Department of Otolaryngology, Tokyo Medical University, Tokyo, Japan
Correspondence:
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Corresponding author: Naoharu Kitajima, Department of Otolaryngology, Tokyo Medical University, 6-7-1 Nishishinjuku Shinjuku-ku, Tokyo 160 0023, Japan. Tel.: +81 3 3342 6111; Fax: +81 3 3346 9275; E-mail: nao-ake@bk2.so-net.ne.jp
Abstract: Pupillary dilation in response to sound stimuli is well established and generally represents a startle reflex to sound. We previously reported that auditory-pupillary responses (APRs) persist with bilateral deafness, and that the pathways mediating APRs involve not only the cochlea but also otolith organs, especially the saccule. Here, we evaluated the vestibulo-autonomic responses in vestibular neuritis (VN) by assessing APRs. Twelve young healthy volunteers without a history of hearing and equilibrium problems and 10 VN patients participated. To clarify the relationship between APRs and vestibular function, especially otolith function, we performed caloric and vestibular-evoked myogenic response testing on VN patients. In normal subjects, we examined APRs when delivering sound stimuli to both sides. In VN patients, we examined APRs when delivering stimuli simultaneously to both sides, to the affected side alone, and then to the unaffected side alone. With binaural stimulation, the pupillary index (PI) – the rate of dilation – of VN patients significantly differed from those of normal subjects. Moreover, in VN patients, PIs of the affected sides were significantly larger than those of the unaffected sides. Our study provides evidence that examining APRs may be useful for evaluating vestibulo-autonomic reflexes, especially otolith-autonomic reflexes.
Keywords: Auditory-pupillary response, vestibulo-autonomic response, vestibular neuritis, otolith function
