IMPAIRED CARDIAC UPTAKE OF META[I-123]IODOBENZYLGUANIDINE IN PARKINSONS-DISEASE WITH AUTONOMIC FAILURE

Objective - To selectively investigate postganglionic sympathetic card iac neurons in patients with Parkinson's disease and autonomic failure . Material and methods - Metaiodobenzylguanidine (MIBG) is a pharmacol ogically inactive analogue of noradrenaline, which is similarly metabo lized in noradrenergic neurons. Therefore the uptake of radiolabelled MIBG represents not only the localization of postganglionic sympatheti c neurons but also their functional integrity. Ten patients with Parki nson's disease and autonomic failure underwent standardized autonomic testing, assessment of catecholamine plasma levels and scintigraphy wi th [I-123]MIBG. Results - The cardiac uptake of MIBG, as demonstrated by the heart/mediastinum ratio, was significantly lower in patients in comparison with controls. Scintigraphy with MIBG allowed the selectiv e in-vivo investigation of postganglionic sympathetic cardiac efferent s in patients with autonomic failure, a procedure which was previously confined to post-mortem examination. Conclusion - These findings poin t to a relevant postganglionic pattern of involvement of the autonomic nervous system (ANS) in Parkinson's disease and autonomic failure.