Auditory interhemispheric transfer deficits, hearing difficulties, and brain magnetic resonance imaging abnormalities in children with congenital aniridia due to PAX6 mutations

Objective: To assess auditory processing, hearing difficulties, and brain magnetic resonance (MR) imaging abnormalities in children with panocular developmental aniridia due to PAX6 mutations. Design: Case-control study. Setting: Great Ormond Street Hospital and Institute of Child Health. Participants: Eleven case subjects with PAX6 mutations and 11 age-matched and sex-matched healthy control subjects. Interventions: All subjects completed a structured hearing questionnaire, baseline audiometry, and central auditory tests (dichotic speech tests, frequency and duration pattern tests, and gaps-in-noise test). Case subjects underwent brain MR imaging with volumetry, and the results were compared with those of age-matched and sex-matched healthy control subjects randomly selected from the Radiology and Physics Unit database. Main Outcome Measures: Brain MR imaging, central auditory test results, and questionnaire scores. Results: The corpus callosum area was significantly smaller on brain volumetry in the cases compared with the controls. The anterior commissure was small in 7 cases and was normal in 3 cases on visual inspection of brain MR images (conducted in 10 of 11 cases). Audiograms showed no abnormalities in any of the children. Central auditory test results were normal in all the controls and were abnormal in all the cases except for 1 case with a pattern of abnormalities consistent with reduced auditory interhemispheric transfer. The cases had greater difficulty localizing sound and understanding speech in noise than the controls. Conclusions: Despite normal audiograms, children with PAX6 mutations may experience auditory interhemispheric transfer deficits and have difficulty localizing sound and understanding speech in noise. In view of their additional visual difficulties, thorough audiological evaluation of these children is indicated to initiate appropriate management.