Auditory brainstem response findings and peripheral auditory sensitivity in adrenoleukodystrophy

Measurements of the auditory brainstem response (ABR) were obtained in 96 individuals with X-linked adrenoleukodystrophy (X-ALD). The patients were divided into five diagnostic groups on the basis of neurologic diagnosis. The five groups were cerebral childhood and adolescent, pure adrenomyeloneuropathy (pure AMN), adrenomyeloneuropathy cerebral (AMN cerebral), Addison's only and symptomatic female heterozygotes. Results indicated the presence of marked ABR abnormalities for all groups most frequently involving Wave V, followed by Wave III and Wave I. Abnormalities of all interpeak latency intervals (i.e., I-III, III-V and I-V) were observed for all groups. ABR abnormalities were most frequently seen in the AMN-cerebral and pure AMN groups but were also common in the symptomatic female heterozygote group. The ABRs in the cerebral childhood and adolescent group were the least impaired of the five groups examined. Age was found to be a significant independent predictor of bilateral ABR abnormalities but VLCFA levels, MRI Loes score, and duration of symptoms were not found to be independent predictors of bilateral ABR abnormalities after adjusting for ALD phenotype. Patients with AMN were significantly more likely to have bilateral ABR abnormalities than the cerebral childhood and adolescent group after adjusting for age, duration of symptoms, EDSS score, VLCFA levels and MRI Loes scores. The prevalence of peripheral hearing loss was not found to exceed that present in age and sex matched normal control groups derived from the NHANES (1999-2000), indicating a lack of association between peripheral hearing loss and X-linked adrenoleukodystrophy. It was concluded that: (1) auditory sensitivity in X-ALD is not significantly impaired; (2) ABR abnormalities are a frequent finding and may be caused by abnormalities of fiber tracts in the region of the lateral lemniscus and inferior colliculus; and, (3) the abnormalities progress slowly and appear to be associated mainly with the AMN phenotype.