Clinical characteristics of patients with Parkinson's disease with reduced 123I-metaiodobenzylguanidine uptake in the major salivary glands and heart

Background: Parkinson's disease (PD) shows cardiac sympathetic denervation (SD) in 123I-meta- iodobezylguanidine (MIBG) scintigraphy. Recently, SD in the major salivary glands (MSG-SD) was introduced as a possible radiological feature of PD. Objective: To identify the clinical characteristics of patients with PD with reduced MSG and cardiac MIBG uptake (dual-SD) compared with those with reduced MSG or cardiac MIBG uptake only (single-SD). Methods: We recruited 90 patients with PD and 30 controls and evaluated their non -motor (e.g., hyposmia, autonomic dysfunction) and motor (e.g., Movement Disorder Society-Unified Parkinson's Disease Rating Scale) features. We also assessed MIBG uptake in the MSG and heart using a quantitative semi-automatic method, and compared MIBG uptakes between PD and controls. We set cut-off values for optimal sensitivity and specificity, and compared the clinical characteristics of patients with PD between dual- and single-SD groups. Results: MSG and cardiac MIBG uptakes were significantly reduced in PD. Sixty-one patients had dual-SD, 25 had single-SD, and four had non-SD. In patients with PD with normal cardiac SD, 76.5% (13/17) of whom showed abnormalities only in MSG-SD. When clinical characteristics were compared between the dual-SD and single-/ non-SD groups, patients in the dual-SD group were older and had more severe hyposmia and autonomic dysfunction, except motor features. Multiple logistic regression analysis identified age as an important confounder. Conclusions: Patients with PD with dual-SD have more severe non -motor features than other patients. Autonomic dysfunction might progress independently from dopaminergic degeneration. Furthermore, our findings indicate that aging is a crucial factor in PD progression.