Abstract
This case report aims to describe the presymptomatic and prodromal phases of the disease in a sporadic patient with amyotrophic lateral sclerosis (ALS). A 41-year-old woman presented with acute hypesthesia due to transverse myelitis, with normal serum NfL levels. After six months, an increase in serum NfL, without clinical correlate, was found. One year after the myelitis, while serum NfL continued to increase, she experienced mild motor symptoms in the right hand, without definite signs of ALS. Disease progression over the following months finally lead to an ALS diagnosis, just as the NfL reached its peak. The emergence of both mild motor impairment as a prodromal stage of disease, and the sustained increase in NfL presymptomatically in a patient with sporadic ALS, highlights the expected similarities between genetic and non-genetic forms of disease. This case suggests the utility of NfL as a risk/susceptibility biomarker for predicting phenoconversion also in sporadic ALS patients.