Loss of dorsolateral nigral hyperintensity on 3.0 tesla susceptibility‐weighted imaging in idiopathic rapid eye movement sleep behavior disorder

We assessed loss of dorsolateral nigral hyperintensity (DNH) on high‐field susceptibility‐weighted imaging (SWI), a novel magnetic resonance imaging marker for Parkinson's disease (PD), in 15 subjects with idiopathic rapid eye movement sleep behavior disorder (iRBD) and compared findings to 42 healthy controls (HCs) and 104 PD patients. We found loss of DNH in at least two thirds of iRBD subjects, which approaches the rate observed in PD and is in contrast to findings in HCs. We propose that absence of DNH on high‐field SWI could identify prodromal degenerative parkinsonism in iRBD. Ann Neurol 2016;79:1026–1030