Hyperacusis in Williams syndrome: characteristics and associated neuroaudiologic abnormalities.

BACKGROUND: Hyperacusis and phonophobia are common, debilitating symptoms in Williams syndrome (WS), yet little is known about their underlying audiologic and neurologic processes.
METHODS: The mothers of 49 subjects with WS were asked to complete the Hyperacusis Screening Questionnaire. Subjects with reported hyperacusis and sufficient developmental capacity underwent comprehensive audiological and brain auditory evoked response (BAER) testing. Findings were compared with those from pair-matched typically developing control subjects.
RESULTS: Forty-one of the 49 children with WS (84%) had hyperacusis of moderate to severe degree, which began in infancy. Of these, 21 (mean age 15.8 +/- 5.5 years) were quantitatively tested. Subjects with WS reported discomfort at sound intensities on average 20 dB lower than control subjects. Pure-tone audiometry and distortion products otoacoustic emission test revealed a high-frequency cochlear hearing loss. An absence of ipsilateral acoustic reflex responses to maximum stimulation was significantly more common in the subjects with WS than controls. On BAER testing, the WS group had a significant prolongation in wave I latency.
CONCLUSIONS: Hyperacusis in Williams syndrome (WS) is associated with a high-frequency hearing loss resembling the configuration of noise-induced hearing loss. The hyperacusis and hearing loss in WS may stem from a deficiency in the acoustic reflex resulting from auditory nerve dysfunction. Additional mechanisms that may mediate hyperacusis in WS and should be evaluated in future studies include recruitment, malformation of the facial canal, and haploinsufficiency of the elastin gene.