Учебники / Genetic Hearing Loss Willems 2004
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Mullen et al. |
ACKNOWLEDGMENTS
This work was supported by grants from the U.S. National Institutes of Health/NIDCD, DC04233, DC00129 and DC00139, and by the Research Service of the U.S. Veterans Administration.
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2
Audiometric Tests and Diagnostic Workup
Paul J. Govaerts
The Eargroup, Antwerp, Belgium
Children with suspected congenital hearing loss are referred for audiological and diagnostic workup. The suspicion is often based on parental anxiety, but more and more children are referred after failing neonatal hearing screening.
The audiological workup aims at establishing the type and degree of hearing loss. Pure tone audiometry is the standard test in daily clinical practice. The technique of pure tone audiometry is explained and some issues that are useful for a good interpretation of audiometric reports are highlighted. Standards are given for age-related deterioration of hearing. In addition, attention is paid to objective tests, such as auditory brainstem responses (ABR), otoacoustic emissions, and tympanometry. These tests play an important role in assessing the hearing of infants or otherwise uncooperative subjects.
The diagnostic workup of hearing loss also aims at refining the diagnosis, excluding associated pathology in case of syndromic hearing loss, and identifying the molecular defect. To exclude associated pathology means looking for syndromes. Typical features such as facial anomalies may be indicative of a syndrome. A thorough clinical examination focusing on any signs of an underlying syndrome is therefore mandatory. In addition, several organs are known to be at risk in case of a congenital hearing problem. These are mainly the kidneys [e.g., branchio-oto-renal syndrome (BOR)], the heart (e.g., long Q-T syndrome), the thyroid (e.g., Pendred syndrome), and the eyes (e.g., Usher syndrome). Special attention should therefore be given to these organs.
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