Auditory-pupillary responses in patients with vestibular neuritis

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.

Trigeminal, Visceral and Vestibular Inputs May Improve Cognitive Functions by Acting through the Locus Coeruleus and the Ascending Reticular Activating System: A New Hypothesis

“…At least in part, the effects of vestibular afferents on cognitive functions could be mediated by the central noradrenergic system arising from the LC, whose neurons are affected by the labyrinthine input (Manzoni et al, 1989 ; Kaufman et al, 1992 ), as confirmed by the observation that vestibular stimulation induces changes in pupil size (Kitajima et al, 2010 , 2013 ), which is a reliable indicator of LC activity (Rajkowski et al, 1993 , 1994 ; Murphy et al, 2014 ). It should be reminded that the vestibular influences on the LC have been proposed as the cause of the development of hemispheric specialization, since, during foetal development, the asymmetric position of the head is likely to favor activation of the left labyrinth during maternal locomotion, leading to an asymmetric development of several central structures (Previc, 1991 ).…”

H-Index Is Important for Postural Control for People with Impaired Foot Sole Sensation

“…In the presence of chronic somatosensory impairments, postural control appears to depend more upon other, intact sources of sensory feedback [ 24 – 26 ]. For example, individuals with PN are more depend upon vestibular feedback, as their postural control is more sensitive to vestibular perturbations as compared to age-matched controls [ 27 ].…”