From neurofilament research to multiple sclerosis clinical practice: Where do we stand?

Comments on an article by J. Kuhle et al. (see record [rid]2017-09383-007[/rid]). Kuhle et al. have investigated the effect of riluzole on serum Nf as well as the relationship between clinical and MRI outcomes and serum Nf levels in patients with MS. The study cohort was composed of a group of patients with early relapsing-remitting MS who participated in a randomized double-blind trial comparing riluzole and placebo as an add-on therapy to weekly interferon-b (IFN-b)– 1a IM. Twenty-two patients randomized to riluzole and 21 to placebo were followed-up for 24 months with serum Nf samples, MRI scans, and clinical and neuropsychological assessments. NfL and NfH levels were measured by ELISA and electrochemiluminescence immunoassay. this study by Kuhle et al. adds a relevant contribution to the current debate on the use of Nf as biomarkers of neuroaxonal damage in MS clinical practice, but leaves important questions still open. While the decrease in serum NfL detected over the follow-up, as well as the correlation with brain atrophy and clinical scores, support the potential of Nf as a biomarker of disease progression and persistent neuroaxonal damage, a key question arises on the real superiority of this serum measure over MRI derived metrics in reflecting neuronal-specific pathologic changes. In particular, the added value of Nf over MRI-derived volume measures sensitive to neuronal damage, such as cortical and deep gray matter volume changes, and more exploratory metrics such as axial diffusivity and MR spectroscopy N-acetylaspartate, is yet to be proven. Moreover, unlike MRI-derived metrics, Nf levels do not provide regional localization information, which can be essential in defining the pathologic course of the disease.