Auditory Processing in Williams
Syndrome: Does Normal
Behavioral Hearing Indicate
Normal Auditory Function?
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1
James Madison University, Department of Communication Sciences and Disorders, United States
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2
University of Louisville, Department of Psychological and Brain Sciences, United States
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3
Boston University School of Medicine, United States
Introduction: Williams syndrome (WS) is a genetic disorder caused by a heterozygous microdeletion on chromosome 7. As individuals with WS present with a hypersensitivity to sound they have historically been assumed to have normal hearing sensitivity. Only recently has it been documented that many individuals with WS actually have a mild to moderate sensorineural hearing loss; in addition, preliminary crosssectional data suggest that the hearing loss is progressive. With prevalence rates of poorer behavioral thresholds ranging from 60% of children to 100% of adults, there is likely to be a strong genetic component to the hearing loss. Our purpose was to further investigate the peripheral auditory functioning of individuals with WS.
Methods: Auditory functioning was assessed through tympanometry (middle-ear function), behavioral auditory, a distortion production otoacoustic emissions screening task (DPOAE; a measure of outer hair-cell function of the inner ear), and a more audiometrically stringent input/output (I/O) functions at 4000 Hz. I/O functions are understood to be an objective, physiologic correlate to behavioral loudness growth function, which may help to explain the hypersensitivity to sound evidenced in this population. And when these DPOAE I/O functions are measured at 4000 Hz, they are also extremely sensitive to possible noise-induced hearing loss. Forty-six individuals with WS participated in the behavioral pure-tone task, 41 participated in the DPOAE screening task, and 11 individuals with WS who had “normal” behavioral hearing participated in the DPOAE I/O function. This final group (WS with normal hearing) will be compared to age- and gender-matched controls with normal behavioral hearing. Participants ranged in age from 6 years to 53 years (Median=15.25).
Results: On the tympanometric condition, 26% of individuals with WS displayed tympanograms indicative of middle ear pathology. Additionally, 85% of individuals failed a behavioral hearing screening and 66% displayed DPOAEs below the 5th percentile according Gorga et al.. Gorga reports that such depressed (poor) outer hair cell activity is indicative of impaired cochlear function (impaired inner ear function). This interpretation finds further support in the DPOAE I/O function. Those individuals with WS who also had “normal” hearing showed significantly depressed outer hair-cell function within the 4000 Hz range as compared to normal-hearing controls [F(1,12) = 23.812, p < 0.01, ηp 2 = 0.665]. This phenomenon is most frequently seen in individuals with noiseinduced hearing loss.
Discussion: Individuals with WS displayed a peripheral auditory impairment greater than that found in the general population. Specifically, pathology was found in both middle ear and cochlear hair cell functioning as evidenced by abnormal tympanograms, poorer behavioral thresholds, poorer DPOAEs, and poorer I/O function. The impaired I/O function may assist in explaining the hypersensitivity to sound in WS. Clinically, our data suggest that a large number of special needs, school-aged children with WS have undiagnosed hearing loss. Theoretically, WS ears may be an experimental model for what has been referred to as “fragile ears”.
Conference:
12th International Professional Conference on Williams Syndrome, Garden Grove,CA, United States, 13 Jul - 14 Jul, 2008.
Presentation Type:
Oral Presentation
Topic:
SESSION 6: Updates on Cognition in Williams Syndrome
Citation:
Marler
JA,
Wightman
FL,
Kistler
DJ,
Roy
JL and
Mervis
CB
(2009). Auditory Processing in Williams
Syndrome: Does Normal
Behavioral Hearing Indicate
Normal Auditory Function?.
Conference Abstract:
12th International Professional Conference on Williams Syndrome.
doi: 10.3389/conf.neuro.09.2009.07.022
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Received:
30 Apr 2009;
Published Online:
30 Apr 2009.
*
Correspondence:
J. A Marler, James Madison University, Department of Communication Sciences and Disorders, Harrisonburg, United States, marlerja@jmu.edu