LAUSR

The relationship between nigrostriatal dopaminergic denervation (NSDD) in cerebellar multiple system atrophy (MSA-C) was evaluated in this issue of Neurology. In their observational cohort of 85 patients with sporadic late-onset cerebellar ataxia, Dr. Wirth et al. compared the predictive potential of NSDD using [1231]-FP-CIT-SPECT against the common clinical Parkinsonism and cerebellar scales (SARA, UPDRS-III, and SDFS) for the diagnosis of possible and probable MSA-C. The investigators found that striatal/occipital dopaminergic binding was lower among patients with MSA-C, decayed more rapidly over time, and had similar sensitivity and specificity as these other scoring systems for a diagnosis of possible MSA-C. Dr. Tieve and colleagues also note that REM sleep behavior disorder (RBD) is suggestive of synucleinopathies such as MSA-C and may augment the sensitivity and specificity of these clinical and radiographic biomarkers. The investigators comment that the diagnosis of RBD requires a comprehensive polysomnogram with electroencephalography—which may not be available at most centers—and further that RBD is only prevalent in ¾ of the patients with MSA-C, which limits its sensitivity as a predictive criterion. When MSA-C is suspected, the investigators agree that RBD may improve the specificity of the diagnosis when this symptom is present.