NEFL and central nervous system neoplasm: The aims of this study were: (1) to compare the CSF NfL levels in MS and non-demyelinating diseases of the CNS, with emphasis on malignant and benign CNS tumors, using a previously validated CSF ELISA kit [17]; (2) to determine the relationship between the clinical and radiological features and CSF NfL levels in patients with MS; and (3) to compare the ELISA and SIMOA methods in terms of reliability for NfL measurement using paired CSF and serum samples.