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 patients with Parkinson's disease and those with multiple system atrophy. However, the fate of the two diseases differs considerably and leads to different strategies for patient management. Differentiation of the two diseases currently requires a combination of several clinical and electrophysiological tests. First studies of myocardial innervation using iodine-123 metaiodobenzylguanidine (MIBG) indicated a possible role of scintigraphy for this purpose. An increase in the pulmonary uptake of 123I-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 123I-MIBG was studied in 21 patients with Parkinson's disease, 7 patients with multiple system atrophy and 13 age- and sex-matched controls. Thoracic images were obtained in the anterior view 4 h after intravenous injection of 185 MBq 123I-MIBG, at which time the maximum neuronal uptake is reached. All patients with Parkinson's disease had significantly lower cardiac uptake of 123I-MIBG than patients with multiple system atrophy and controls. Sympathetic innervation of the lung was not affected in either disease. It is concluded that scintigraphy with 123I-MIBG appears to be a useful tool for differentiation between Parkinson's disease and multiple system atrophy early after onset of autonomic dysfunction.