CSF analysis differentiates multiple-system atrophy from idiopathic late-onset cerebellar ataxia

Background: Differentiating idiopathic late-onset cerebellar ataxia (ILOCA) from ataxia due to the cerebellar subtype of multiple-system atrophy (MSA-C) can be difficult in the early stages of the disease Methods: The authors analyzed the levels of various CSF biomarkers in 27 patients with MSA-C and 18 patients with ILOCA and obtained cut-off points for each potential biomarker to differentiate MSA-C from ILOCA. Results: Increased levels of neurofilament light chain (NFL) and neurofilament heavy chain (NFHp35) and decreased levels of the neurotransmitter metabolites homovanillic acid (HVA), 5-hydroxyindoleaceticacid (5-HIAA), and 3-methoxy-4-hydroxyphenylethyleneglycol ( MHPG) were observed in MSA-C compared with ILOCA patients. Receiver operating characteristic analysis showed high sensitivity and specificity levels for NFL, NFHp35, and MHPG analysis. At a cut-off of 24.4 ng/L for the NFL analysis, a sensitivity of 79% and a specificity of 94% were obtained for differentiating MSA-C from ILOCA. At a cut-off point for NFHp35 of 129.5 ng/L, sensitivity was 87% and specificity 83%. Analysis of MHPG levels ( cut-off 42.5 nM) resulted in a sensitivity of 86% with a specificity of 75%. A multivariate logistic regression model selected NFL, MHPG, and tau as independent predictive biomarkers that separated the MSA-C and ILOCA groups. Conclusions: Increased levels of neurofilament light chain and tau and decreased levels of 3-methoxy-4-hydroxyphenylethyleneglycol were associated with high accuracy levels in differentiating the cerebellar subtype of multiple-system atrophy from idiopathic late-onset cerebellar ataxia (LOCA). CSF analysis may thus serve as a useful tool in early diagnostic differentiation of LOCA.