Scintigraphic differentiation between two forms of primary dysautonomia early after onset of autonomic dysfunction: value of cardiac and pulmonary iodine-123 MIBG uptake

Primary dysfunction of the autonomic nervous system can be observed in pati ents with Parkinson's disease and those with multiple system atrophy, Howev er, the fate of the two diseases differs considerably and leads to differen t strategics for patient management. Differentiation of the two diseases cu rrently requires a combination of several clinical and electrophysiological tests. First studies of myocardial innervation using iodine-123 methaiodob enzylguanidine (MIBG) indicated a possible role of scintigraphy for this pu rpose. An increase in the pulmonary uptake of I-123-MIBG has been reported in secondary dysautonomias. Whether sympathetic innervation of the lung is affected in primary dysautonomias is currently unknown, Therefore, cardiac and pulmonary uptake of I-123-MIBG was studied in 21 patients with Parkinso n's disease, 7 patients with multiple system atrophy and 13 age- and sex-ma tched controls. Thoracic images were obtained in the anterior view 4 h afte r intravenous injection of 185 MBq I-123-MIBG, at which time the maximum ne uronal uptake is reached. All patients with Parkinson's disease had signifi cantly lower cardiac uptake of I-123-MIBG than patients with multiple syste m atrophy and controls, Sympathetic innervation of the lung was not affecte d in either disease. It is concluded that scintigraphy with I-123-MIBG appe ars to be a useful tool for differentiation between Parkinson's disease and multiple system atrophy early after onset of autonomic dysfunction.