Cardiovascular dysautonomia in Parkinson's disease and multiple system atrophy

Objectives - To determine whether Parkinson's disease (PD) can be distinguished from multiple system atrophy (MSA) on the basis of the assessment of iodine-123 meta-iodobenzylguanidine ( 123 I-MIBG) radioactivity in heart and cardiovascular autonomic function. Patients and methods - Seventeen patients with MSA, 39 with PD, and 25 healthy volunteers underwent 123 I-MIBG scintigraphy and hemodynamic autonomic function tests using Valsalva maneuver (VM). Baroreceptor reflex sensitivity (BRS) was measured using the slope of the relation between RR interval and blood pressure during the fourth phase. Results - 123 I-MIBG radioactivity in heart of patients with PD was lower than that of control subjects and patients with MSA, but there was some overlap between PD and MSA. BRS in patients with PD who had a 123 I-MIBG radioactivity similar to that in MSA was larger than that in patients with MSA, with no overlap in any patient. Conclusion - Assessment of BRS may be useful for differentiating between MSA and PD that had a 123 I-MIBG radioactivity similar to MSA.