Early involvement of sympathetic cardiac nerve endings in a patient with rem sleep behaviour disorders

Background REM sleep behaviour disorder (RBD) is a parasomnia characterized by suppression of muscular atonia and abnormal, often violent, motor behaviours during REM sleep. RBD can be either idiopathic or associated with degenerative disorders, such as dementia with Lewy bodies (LBD), multiple system atrophy (MSA), progressive sopranuclear paralysis (PSP) or Parkinson’s disease (PD). Myocardial 123Metaiodiobenzylguanidine (MIBG) enables the assessment of postganglionic sympathetic cardiac never terminals. Reduced myocardial MIBG uptake of the tracer suggests cardiac sympathetic denervation. MIBG uptake allows a differentiation between Lewy body disease and taupathies and other parkinsonisms. Indeed cardiac innervation is impaired in nearly all patients with PD and LBD, while it is preserved in patients with parkinsonisms, such as MSA and PSP. Recently, decreased MIBG uptake has been also described in patients with RBD.