Iodine-123 meta-iodobenzylguanidine ([I-123]MIBG), an analogue of norepinephrine, is a tracer for functioning of sympathetic neurons. To investigate cardiac sympathetic function in PD, SND, and PSP, [I-123]MIBG myocardial scintigraphy was performed in 25 patients with PD, 15 patients with SND, 14 patients with PSP and 20 control subjects. In planar imaging studies, the heart-to-mediastinum average count ratio (HIM) was calculated for both early and delayed images. The mean value of HIM in patients with PD was significantly lower than those with SND, PSE or no disease. Regardless of disease severity or intensity of anti-Parkinsonian pharmacotherapy, mean values for H/M were always low in patients with PD. The mean value of HIM in SND with orthostatic hypotension (OH) was lower than that in SND without OH. Although the mean value of H/M in PSP with amitriptyline treatment was significantly lower than that in PSP patients without amitriptyline treatment, there was no significant difference between the mean Value of H/M in PSP patients without amitriptyline treatment and that in control. Thus, PD may have a abnormality of cardiac sympathetic function which has not been detected by previous cardiovascular autonomic studies. Moreover, particularly in early stages, [I-123]MIBG myocardial scintigraphy may provide helpful diagnostic information in these akinetic-rigid syndromes. (C) 1998 Elsevier Science B.V.
