Objective: To define hyperacusis in audiologic parameters and to further elucidate central and peripheral auditory pathways.
Design and setting: Theories surrounding hyperacusis have always been highly debated. A group of children with Williams syndrome universally complain of hyperacusis. They have highly reproducible behavioural responses to noise and are thus hampered in their social interactions. Loss of inhibitory modulation to efferent sensory input to the cochlea is thought to be a possible mechanism.
Methods: Nine patients with Williams syndrome received a complete audiologic work-up, including audiogram, speech reception thresholds, acoustic reflexes, impedance, and transient evoked otoacoustic emissions (TEOAEs).
Main outcome measures: Assessment of the efferent system is done by measuring changes in TEOAEs following stimulation of the contralateral ear.
Results: Three patients had high-frequency sensorineural hearing loss (SNHL) and thus, as expected, absent TEOAEs, indicating cochlear damage. Two had normal hearing and normal TEOAEs. However, four patients had normal hearing with absent TEOAEs.
Conclusions: These findings are suggestive of cochlear disease and may, in fact, support the hypothesis of outer hair cell modulation by the ipsilateral medial olivocochlear system. Behavioural aspects of the syndrome make audiologic testing difficult. Thus, the diagnosis of SNHL may be hampered if it truly exists. The data show a preponderance of SNHL in the older age groups of our study population. This either reflects previously missed diagnoses or underlying cochlear disease, which may manifest later in life. Thus, this finding blurs the boundary between loudness recruitment and hyperacusis.