CSF neurofilament protein analysis in the differential diagnosis of ALS.

Abstract

BACKGROUND: Cerebrospinal fluid (CSF) biomarkers have been studied to differentiate between patients with ALS and neurological controls, but not in comparison to clinically more relevant disorders mimicking ALS. METHODS: In this retrospective study, CSF concentrations of various brain-specific proteins were analyzed in patients with ALS (n = 32) and ALS-mimic disorders (n = 26). RESULTS: CSF concentrations of neurofilament light (NFL) and heavy chain (NFHp35), but not other brain-specific proteins, were significantly higher in patients with ALS than in patients with an ALS-mimic disorder, however with maximum sensitivity or specificity of 80%. The mean CSF level of NFHp35 was 781 ng/L in the ALS group vs. 338 ng/L in the ALS-mimic disorders group and for NFL the mean CSF levels were 62 ng/L vs. 24 ng/L. CONCLUSION: Although CSF concentrations of NFL and NFHp35 are higher in patients with ALS, the diagnostic accuracy for differentiating ALS from ALS-mimic disorders seems insufficient. Our results suggest that, in the clinical work-up of patients suspected of ALS, application of CSF analysis alone is limited but may have potential in combination with other clinical and electrophysiological markers.