RBD and the Autonomic Nervous System

Abstract

RBD patients are documented to have various autonomic symptoms at high risk of developing synucleinopathies, in which autonomic function is prominently disrupted. The fact that idiopathic RBD patients have greater autonomic dysfunction than controls but not so severe as PD/DLB, corresponding to the pathological course in which idiopathic RBD predates PD/DLB. The autonomic symptoms in idiopathic RBD vary from gastrointestinal, urinary, cardiovascular, sexual, or pupillomotor dysfunction; these symptoms are proposed as supportive clinical features for the clinical diagnosis of probable and possible DLB and criteria items of prodromal PD. Autonomic symptoms per se especially in cases where single symptoms occur can neither indicate central nervous system neurodegeneration nor predict future development of PD/DLB, although combinations of the symptoms and other clinical features characterizing synucleinopathies are expected to be useful for predicting future phenoconversion of idiopathic RBD. The variety of types and occurrence rate of autonomic symptoms in idiopathic RBD could reflect heterogeneity in pathological progression of synucleinopathies.