AS aggregates occur in epicardial pANS in subjects without parkinsonism, suggesting the diagnosis of iLBD. The presence in some of these subjects of non-motor symptoms such as acting dreams and constipation known to occur in premotor PD supports this interpretation. Adequate follow-up of the subjects in this study will indicate the time, if any, to progression to motor PD.

Nigrostriatal involvement is considered an additional feature in the new consensus criteria for the diagnosis of the cerebellar variant of multiple system atrophy (MSA-C). However, so far, only a few studies, which include a relative small number of patients, give support to this criterion. Our objective was to assess nigrostriatal dopaminergic innervation in patients with MSA-C without parkinsonism by use of dopamine transporter single photon emission computed tomography (DAT SPECT). Thirteen patients that fulfilled criteria for possible or probable MSA-C and presented no parkinsonian signs, and 12 age-matched healthy controls underwent ((123)I-2-β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane ([(123)I]FP-CIT) SPECT. Patients were also evaluated through the Unified Multiple System Atrophy Rating Scale (UMSARS) and brain magnetic resonance imaging (MRI). The mean duration of the cerebellar syndrome was 3.8 ± 1.7 years. DAT SPECT showed a significant decrease of striatal [(123)I]FP-CIT uptake ratios in patients (p < 0.001). Radiotracer uptake reduction was 21% in the entire striatum, 19% in putamen, and 24% in caudate nuclei. Striatal binding ratios were within the normal range in 3 patients. We did not find correlation between striatal uptake and disease duration, age of patients, UMSARS-II score, and pontine diameter. [(123)I]FP-CIT SPECT shows that most but not all MSA-C patients without parkinsonism have subclinical nigrostriatal dopaminergic denervation which is not related to disease duration, cerebellar dysfunction, or pontine atrophy.