A RADIOLOGICAL ANALYSIS OF HEART SYMPATHETIC FUNCTIONS WITH META-[I-123]IODOBENZYLGUANIDINE IN NEUROLOGICAL PATIENTS WITH AUTONOMIC FAILURE

Cardiac scintigraphy with meta-[I-123]iodobenzylguanidine (MIBG) is us ed to assess cardiac sympathetic function. We performed [I-123]MIBG sc intigraphy in 7 patients with neurological diseases presenting orthost atic hypotension and other autonomic failures (AF), 22 neurological pa tients without AF, and 9 healthy subjects. Thallium scintigraphy and e chocardiography were also performed in all subjects. In this series, p atients with any evidence of cardiac dysfunction were excluded. No [I- 123]MIBG accumulation was observed in all patients with AF, and cardia c defects were noted in 7 patients (5 with Parkinson's disease [PD], 2 with spinocerebellar degenerations [SCD]), and in some patients witho ut AF. In contrast, the distribution of [I-123]MIBG was normal in all the healthy subjects. No decrease in [I-123]MIBG accumulation was resu lted from drug therapy (droxidopa, amezinium and thyrotropin-releasing hormone). In conclusion, reduced accumulation on [I-123]MIBG scintigr aphy may be due to myocardial beta-adrenoceptor dysfunction or reduced central sympathetic activity of the heart, or both.