Analysis of subtle auditory dysfunctions in young normal-hearing subjects affected by Williams syndrome

To assess if young subjects affected by Williams syndrome (WS) with normal middle ear functionality and normal hearing thresholds might have subtle auditory dysfunctions that could be detected by using clinically available measurements.

Otoscopy, acoustic reflexes, tympanometry, pure-tone audiometry, and distortion product otoacoustic emissions (DPOAEs) were measured in a group of 13 WS subjects and in 13 age-matched, typically developing control subjects. Participants were required to have normal otoscopy, A-type tympanogram, normal acoustic reflex thresholds, and pure-tone thresholds≤15 dB HL at 0.5, 1, and 2 kHz bilaterally. To limit the possible influence of middle ear status on DPOAE recordings, we analyzed only data from ears with pure-tone thresholds≤15 dB HL across all octave frequencies in the range 0.25-8 kHz, middle ear pressure (MEP)>-50 daPa, static compliance (SC) in the range 0.3-1.2 cm3, and ear canal volume (ECV) in the range 0.2-2 ml, and we performed analysis of covariance to remove the possible effects of middle ear variables on DPOAEs.

No differences in mean hearing thresholds, SC, ECV, and gradient were observed between the two groups, whereas significantly lower MEP values were found in WS subjects as well as significantly decreased DPOAEs up to 3.2 kHz after adjusting for differences in middle ear status.

Results revealed that WS subjects with normal hearing thresholds (≤15 dB HL) and normal middle ear functionality (MEP>-50 daPa, SC in the range 0.3-1.2 cm3, ECV in the range 0.2-2 ml) might have subtle auditory dysfunctions that can be detected by using clinically available methods. Overall, this study points out the importance of using otoacoustic emissions as a complement to routine audiological examinations in individuals with WS to detect, before the onset of hearing loss, possible subtle auditory dysfunctions so that patients can be early identified, better monitored, and promptly treated.