Auditory brainstem responses in patients with autonomic failure with Parkinson's disease and multiple system atrophy

Auditory brainstem responses (ABRs) were examined in six patients with auto nomic failure with Parkinson's disease (AF with PD) and 10 patients with au tonomic failure with multiple system atrophy (AF with MSA), all of which sh owed marked parkinsonian features as a principal sign. We designated the ce ntral abnormalities of ABRs as prolongation of latencies (wave LU or V) and interpeak latencies (IPLs; I-m, I-v, and m-V IPL) or decreased amplitude r atios of wave III or V to those of wave I (less than 1.0). None of the pati ents with AF with PD showed abnormalities in ABRs. In contrast, in those wi th AF with MSA, the peak latencies or IPLs were prolonged in two of the 10 patients, and the amplitude ratios of wave III or V to those of wave I were decreased in other two of these patients. Moreover, both prolongation of l atencies and a decreased ratio were observed in other one. Overall, five of the 10 patients with AF with MSA showed central abnormalities in ABRs. It is clinically difficult to differentiate AF with PD from AF with MSA, parti cularly when no cerebellar signs are apparent in AF with MSA patients. When central abnormalities of ABRs are observed in AF patients, AF with MSA sho uld be suspected rather than AF with PD. In conclusion, ABRs provide useful information for the differential diagnosis of AF with PD and AF with MSA. (C) 1999 Elsevier Science B.V. All rights reserved.