A recent study assessed the effectiveness of serum neurofilament light chain (NfL) and cerebrospinal fluid (CSF) phosphorylated neurofilament heavy chain (pNfH) as biomarkers to differentiate between motor neuron disease (MND) and multifocal motor neuropathy (MMN). The retrospective study included 16 patients with MMN and 34 newly diagnosed patients with MND, with a subset of 24 lower motor neuron (MN) dominant patients with MND analyzed separately. Measurements were taken using Ella automated immunoassay for serum NfL and enzyme-linked immunosorbent assay for CSF pNfH. The study calculated the area under the curve (AUC), optimal cutoff values, and correlations with demographic characteristics.

Results indicated significantly higher neurofilament concentrations in MND compared to MMN. Serum NfL and CSF pNfH showed strong correlation (Spearman’s rho 0.68) and excellent performance in distinguishing MND from MMN, with AUC values of 0.946 and 0.937, respectively. Optimal cutoff values were ≥44.15 pg/mL for serum NfL and ≥715.5 pg/mL for CSF pNfH. Only one MMN patient exceeded the serum NfL cutoff, and two MND patients with slowly progressive disease had neurofilament levels below the cutoffs. These findings suggest that elevated neurofilaments can significantly support MND diagnosis in cases of diagnostic uncertainty.

Reference: Wohnrade C, Seeliger T, Gingele S, et al. Diagnostic value of neurofilaments in differentiating motor neuron disease from multifocal motor neuropathy. J Neurol. 2024 Jul;271(7):4441-4452. doi: 10.1007/s00415-024-12355-8.