Relevance of serum neurofilament light chain determination as a biomarker in multiple sclerosis. Consensus of the Spanish Society of Neurology's Study Group on Multiple Sclerosis and Related Neuroimmune Diseases.

INTRODUCTION

Multiple sclerosis (MS) is an inflammatory, degenerative disease of the central nervous system with a complex and uncertain etiology. Although therapeutic advances have improved disease control, both prognosis and treatment monitoring continue to be challenging. Serum neurofilament light chain (sNfL), a marker of neuroaxonal damage, is emerging as a useful biomarker to improve disease monitoring.

DEVELOPMENT: This article addresses the interpretation of sNfL levels in patients with MS and their correlation with inflammatory activity and disease progression. We also discuss the role of sNfL in detecting subclinical axonal damage, which may allow for adjustments in therapeutic decision-making at different stages of the disease.

CONCLUSIONS

Incorporating sNfL measurement into the routine practice of neurologists, as a complement to clinical evaluation and magnetic resonance imaging, represents an advance in the follow-up of patients with MS. In specific scenarios, as detailed in the article, it can help optimise therapeutic decision-making and prevent further neuroaxonal damage. While the current evidence is already strong, further validation of its application is necessary. The widespread use of this biomarker by neurologists is a key step in generating that evidence.