Relationship between (123)I-MIBG scintigrams and REM sleep behavior disorder in Parkinson's disease

Uptake of (123)I-labeled meta-iodobenzylguanidine (MIBG) in myocardial scintigrams has been shown to be as low in patients with idiopathic RBD as in Parkinson's disease (PD) patients. AIM FOR STUDY: To clarify whether the existence of RBD accelerates autonomic dysfunction in PD, we investigated the association between MIBG scintigraphic findings and RBD measures among non-dementia PD patients. We conducted clinical interviews to assess REM sleep behavior disorder (RBD) symptoms, and performed polysomnograms (PSG) recordings and MIBG scintigrams on 49 PD patients. The patients were divided into three groups (PD with clinical RBD, PD with subclinical RBD, and PD with normal REM sleep). PD patients with clinical RBD had reduced MIBG uptake as determined by heart-to-mediastinum ratios of the delayed image compared to those with subclinical RBD and those with normal REM sleep. Multiple linear regression analysis revealed that only the existence of RBD symptoms was significantly associated with reduced MIBG uptake among PD patients without dementia after adjusting for demographic and PD symptom-related variables. PD patients with clinical RBD might suffer from a wider α-synuclein pathology, including reduced cardiac sympathetic ganglia function as reflected by a lowered MIBG uptake.