Nigrostriatal dysfunction in RFC1-related disorder/CANVAS

Parkinsonism is now recognized as an additional feature in RFC1/CANVAS syndrome; however, no systematic evaluation of nigrostriatal dopaminergic function has been published so far.This is an observational, single-center study, which analyzed 13 patients with molecular confirmation of RFC1/CANVAS. Disease severity was assessed with the SARA scale. Each subject was carefully evaluated for the presence of parkinsonian features. Dopamine transporter (DAT) imaging was acquired and reconstructed in the transverse, coronal and sagittal planes 4 h after venous injection of 99mTc-TRODAT-1. An experienced nuclear physician performed the visual analysis of all images.Patients had a mean age of 62.3 ± 8.8 years, and there were 9 women. The mean SARA score was 15.5 ± 5.8. Nine patients had abnormal DAT imaging results. The putamen was more frequently affected than the caudate nucleus on both sides. Considering all regions, uptake of 99mTc-TRODAT-1 did not correlate with disease duration or SARA scores. Parkinsonism was noticed in 3/13 patients, all of which had abnormal DAT scans. Interestingly, six subjects had reduced DAT imaging uptake, but no clinical signs of parkinsonism.Nigrostriatal dysfunction is frequent in RFC1/CANVAS even in the absence of clinical parkinsonism and may occur early in the disease course.