Effects of Unilateral Audio-Vestibular Insufficiency on Spatial Hearing

This study aimed to compare spatial hearing performance between adult individuals with the unilateral sensorineural hearing loss and unilateral loss of horizontal semicircular canal function (termed canal paresis/weakness) in the same ear and adults with normal hearing thresholds and normal vestibular function and to examine associated factors (duration of hearing loss and rate of canal paresis).The study participants consisted of 20 adults (aged 48 +/- 11 years) with unilateral sensorineural hearing loss and unilateral canal paresis (unilateral weakness >= 25%) in the same ear. The control group comprised 25 adults (aged 45 +/- 13 years) with normal hearing and a unilateral weakness rate below 25%. Pure tone audiometry, bithermal binaural air caloric test, Turkish Spatial Hearing Questionnaire (T-SHQ), and Standardized Mini-Mental State Exam were applied to all the individuals. When the performance of the participants in T-SHQ was examined both in terms of the subscales and the total scale, there was a statistically significant difference between the two groups in relation to the scores. A statistically significant, high, negative correlation was detected between the duration of hearing loss, the rate of canal paresis and all the subscale scores and total score of T-SHQ. According to these results, as the duration of hearing loss increased, the scores obtained from the questionnaire decreased. As the rate of canal paresis increased, vestibular involvement increased, and the T-SHQ score decreased. This study showed that adults with unilateral hearing loss and unilateral canal paresis in the same ear had lower spatial hearing performance than those with normal hearing and balance.