Page 144 - Demo

Chapter 4142Hearing lossThe proportion of adults with hearing loss (78.3%) was much higher in comparison to two previous studies in adults with 22q11.2DS that reported hearing loss in 28.5% and 40.9%, respectively.3, 8 However, when interpreting the findings, it is important to take into account the study designs, definitions for hearing loss, and age and size of the samples in the different studies. The first study was a retrospective chart review in 78 adults at a mean age of 31.5±10.5 years, and included those with hearing loss reported in the medical records.3 No audiological assessments were performed. The proportion of adults with a documented history of hearing loss was similar to this study (28.5% versus 31.7%). In the second study, 22 of 24 adults underwent an audiological assessment at a mean age of 25 (range 19-38) years.8 The same definition for hearing loss was used as in this study. However, in the current study hearing was measured up to 8, instead of 6 kHz. Also, sensorineural hearing loss was found in 33.3% (n=3) of those with hearing loss, comparable to findings in the current study (35.9%). Unilateral conductive hearing loss was found in a much higher proportion of the participants (44.4% versus 12.8%) compared to this study. However, absolute numbers were low affecting reliability of those findings, and results were possibly influenced by a few younger participants.8Another study, reporting on hearing in 40 children and adults at a mean age of 15 years (range 6 -36 years), who received audiological testing as part of the research study, found 60% of participants to have hearing loss in at least one ear, defined as >20 dB HL from 0.5-1-2 kHz.16 Conductive hearing loss was the most common type (54%), sensorineural (4%) or mixed (2%) were found less often.16 In line with results from our study, they did find highfrequency hearing loss in the majority of individuals, which was assumed to be of sensorineural origin.Potential contributors to hearing loss in 22q11.2DSThere are several potential contributors to hearing loss in adults with 22q11DS.7, 17 First, chronic otitis media, with or without congenital inner ear abnormalities,18 may result in the cochlea being more vulnerable in individuals with 22q11.2DS compared to the general population.7, 16 Second, early physiological degeneration and other medical conditions and their treatment, may lead to hearing loss.19 Age-related disorders such as Parkinson’s disease