Evaluation of Vestibular Function in Sleep Disorders

Abstract

Objectives: The aim of this study was to evaluate dizziness in patients with sleep disorders, objectively identify vestibular function through the vestibulo-ocular reflex (VOR) using the video Head Impulse Test (vHIT), and evaluate the association between these findings.Methods: Among the patients who visited the sleep clinic from June to October 2021, 69 who underwent both polysomnography (PSG) and vHIT were included. Participants completed questionnaires including the Dizziness Handicap Inventory (DHI), Beck Anxiety Inventory, Korean-Beck Depression Inventory-II, Epworth Sleepiness Scale, Insomnia Severity Index (ISI), and Pittsburgh Sleep Quality Index (PSQI). The subjects were classified into four groups: insomnia (n=4), rapid eye movement sleep behavior disorder (RBD) (n=13), obstructive sleep apnea syndrome (OSAS) (n=34), and RBD and OSAS (n=18). Moderate to severe OSAS (n=49) was compared with no OSAS and mild OSAS (n=20).Results: In comparison of the four groups according to sleep disorders, the OSAS patients showed the highest DHI scores and the lowest VOR gain, but statistical significance was not found. Although all VOR gains were within the normal range, the VOR gain of the left posterior semicircular canal was significantly lower in the moderate to severe OSA group than in the no OSA and mild OSA groups (1.02±0.18 vs. 0.94±0.10, <i>p</i>=0.019). DHI total scores showed no correlation with VOR gain but showed a positive correlation with ISI (r=0.422, <i>p</i>=0.001) and PSQI (r=0.287, <i>p</i>=0.022). Among PSG parameters, lowest oxygen saturation (SaO₂) and percentage of time with SaO₂ less than 90% were correlated with the emotional score of DHI (r=-0.245, <i>p</i>=0.043 and r=0.311, <i>p</i>=0.010, respectively).Conclusions: Although our study could not objectively confirm vestibular dysfunction in patients with sleep disorders, we found that subjective sleep complaints were associated with dizziness and hypoxic conditions during sleep were associated with emotional aspects of dizziness. This suggests that the treatment of concomitant sleep disorders may improve dizziness.