Audiological follow-up of 24 patients affected by Williams syndrome

Williams syndrome is a neurodevelopmental disorder associated with cardiovascular problems, facial abnormalities and several behavioural and neurological disabilities. It is also characterized by some typical audiological features including abnormal sensitivity to sounds, cochlear impairment related to the outer hair cells of the basal turn of the cochlea, and sensorineural or mixed hearing loss, predominantly in the high frequency range. The aim of this report is to describe a follow-up study of auditory function in a cohort of children affected by this syndrome. 24 patients, aged 5-14 years, were tested by means of air/bone conduction pure-tone audiometry, immittance test and transient evoked otoacoustic emissions. They were evaluated again 5 years after the first assessment, and 10 of them underwent a second follow-up examination after a further 5 years. The audiometric results showed hearing loss, defined by a pure tone average >15 dB HL, in 12.5% of the participants. The incidence of hearing loss did not change over the 5-year period and increased to 30% in the patients who underwent the 10-year follow-up. Progressive sensorineural hearing loss was detected in 20% of the patients. A remarkable finding of our study regarded sensorineural hearing impairment in the high frequency range, which increased significantly from 25% to 50% of the participants over the 5-year period. The increase became even more significant in the group of patients who underwent the 10-year follow-up, by which time the majority of them (80%) had developed sensorineural hearing loss. Otoacoustic emissions were found to be absent in a high percentage of patients, thus confirming the cochlear fragility of individuals with Williams syndrome. Our study verified that most of the young Williams syndrome patients had normal hearing sensitivity within the low-middle frequency range, but showed a weakness regarding the high frequencies, the threshold of which worsened significantly over time in most patients.