Auditory brainstem responses in young males with Fragile X syndrome

Fragile X syndrome (FXS) is the most common inherited cause of mental retardation resulting in developmental delays in males. Atypical outer ear morphology is characteristic of FXS and may serve as a marker for abnormal auditory function. Despite this abnormality, studies of the hearing of young males with FXS are generally lacking. A few studies have suggested that a significant proportion of individuals with FXS demonstrate prolonged auditory brainstem response (ABR) latencies. The purpose of this study was to determine whether young males with FXS display atypical auditory brainstem function compared to typically developing males when conductive and sensorineural hearing loss are ruled out as possible contributors to atypical findings. Participants were 23 males with FXS, 21 typically developing males who were matched for developmental age, and 17 typically developing males who were matched for chronological age. A battery of tests to assess peripheral hearing, cochlear function, and auditory pathway integrity through the level of the brainstem was completed. Males with FXS were similar to typically developing males who were matched for developmental age level or chronological age level on all measures. They had normal hearing sensitivity and middle ear function and scored similar to the typically developing children on the measures of auditory brainstem pathway integrity. In summary, ABRs in young males with FXS were within normal limits.