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. Supplementary Information: The online version contains supplementary material available at 10.1007/s12070-022-03442-1.

Which stimulus should be used for auditory brainstem response in newborns; CE-Chirp® level specific versus Click stimulus.

OBJECTIVES: Auditory Brainstem Response (ABR), the electrical responses in the neuronal pathways extending from the inner ear to the auditory cortex, are evaluated with auditory stimuli. ABR analysis evaluates waves I, III and V's absolute-latencies, amplitude values, interpeak-latencies, interaural-latency differences, and morphologies. This study aims to reveal the advantages of CE-Chirp® LS stimulus and its clinical uses to increase by comparing the amplitude, latency, and interpeak-latency differences of waves I, III, and V at 80 dB nHL and wave V at 60, 40, 20 dB nHL by using click and CE-Chirp® LS stimuli. METHODS: 100 (54 boys, 46 girls) infants with normal hearing were included in the National Newborn Hearing Screening Program. With the click and CE-Chirp® LS ABR, the absolute latency and amplitude values of wave V at 20, 40, and 60 dB nHL, and the absolute-latency, interpeak-latency, and amplitude values of waves I, III, and V at 80 dB nHL are determined between stimuli and right-left ear. RESULTS: When the wave V latency and amplitudes obtained at 80, 60, 40, and 20 dB nHL levels were examined between genders, and according to the risk factor, no significant difference was found between click and CE-Chirp® LS stimuli (p > 0.05). Waves I, III, and V absolute-latency, amplitudes were compared at 80 dB nHL and wave V absolute-latency, amplitudes at 60, 40, and 20 dB nHL; the amplitudes measured with CE-Chirp® LS were significantly higher than the click stimulus (p < 0.05). When two stimuli were compared for I-III and III-V interpeak-latency values at 80 dB nHL level, no significant difference was found between the two stimuli (p > 0.05). However, the I-V interpeak-latency value was statistically significantly decreased for two stimuli, regardless of the ear (p < 0.05). CONCLUSIONS: It is suggested to increase the use of CE-Chirp® LS stimulus with better morphology and amplitude in clinics, believing that it facilitates clinicians' interpretation.

Auditory brainstem response in unilateral tinnitus patients: does symmetrical hearing thresholds and within-subject comparison affect responses?

OBJECTIVE: In recent studies, cochlear synaptopathy has been suggested as a potential pathophysiology mechanism for tinnitus, which occurs in individuals with normal hearing thresholds. Auditory Brainstem Response (ABR) is a noninvasive method frequently used in the literature to evaluate cochlear synaptopathy in tinnitus patients. However, possible factors such as high-frequency pure-tone hearing thresholds, age, gender, and head characteristics that may affect ABR were not considered sufficiently in previous studies. Therefore, the present study aims to evaluate tinnitus ears and non-tinnitus ears with ABR in unilateral chronic tinnitus patients with symmetrical hearing. METHODS: Twenty unilateral chronic tinnitus patients having normal pure-tone average with symmetrical hearing thresholds was included in the study. Subjects were evaluated with 0.25-16 kHz pure-tone audiometry, Tinnitus Handicap Inventory (THI) and ABR were administered. All ears were evaluated monaurally using click stimuli at 80 dB nHL, alternating polarity (21.1 rate/s, 2000 sweeps). RESULTS: Wave I amplitude of the ABR and the ratio of III/I, V/I, and V/III wave amplitudes from tinnitus ears was higher than non-tinnitus ears. At the same time, there was a positive correlation between THI and V-I and V-III interpeak latency range, and a negative correlation between V/III wave amplitude ratio. CONCLUSION: ABR can be used as an evaluation method to provide evidence that the neural organizations of individuals with chronic tinnitus differ in certain regions in their auditory pathways. The correlation between THI and ABR findings suggests that there may be a connection between tinnitus distress and the neural organization of the auditory system.