Auditory brainstem evoked response in the X-linked adrenoleukodystrophy and in Addison's disease [Potenziali evocati uditivi del tronco encefalico nell'adrenoleucodistrofia X-linked e nel morbo di Addison]

X-linked adrenoleukodystrophy (ALD) is a genetic disease characterized by an impaired oxidation of saturated very long chain fatty acids (VLCFA) that accumulate in various tissues and body fluids. The clinical aspects are related to the demyelination of the central nervous system and the adrenocortical insufficiency (Addison's disease). Aim of this study was to evaluate the diagnostic sensitivity for ALD of abnormal auditory brain-stem evoked responses (ABR) in 16 patients with Addison's disease. The electrophysiological ABR study showed severe abnormalities in 4/16 (25%) patients. Elevated plasmatic VLCFA were found in all the patients with severe ABR abnormalities. Among the remaining patients, 0/12 had elevated VLCFA and 5/12 showed only mild ABR abnormalities. The results of our study demonstrate that severe ABR abnormalities are frequently present in ALD patients, even before the appearance of clinical neurological symptoms. Because of their high diagnostic sensitivity, ABR could then be proposed for the screening and the clinical follow-up of ALD patients.