Neurofilament Light Chain Concentration in Cerebrospinal Fluid in Children with Acute Nontraumatic Neurological Disorders.

(1) Introduction: This pilot study aimed to analyze neurofilament light chain levels in cerebrospinal fluid (cNfL) in a cohort of children with different acute nontraumatic neurological conditions. (2) Methods: This prospective observational cohort study consisted of 35 children aged 3 months to 17 years and was performed from November 2017 to December 2019. Patients' clinical data were reviewed, and patients were assigned to the following groups: n = 10 (28.6%) meningitis, 5 (14.3%) Bell's palsy, 7 (20.0%) febrile non-CNS infection, 3 (8.6%) complex febrile seizure, 4 (11.4%) idiopathic intracranial hypertension, and 6 (17.1%) others. cNfL levels were measured using a sensitive single-molecule array assay. (3) Results: The cNfL levels [median (range)] in children with meningitis were 120.5 pg/mL (58.1-205.4), in Bell's palsy 88.6 pg/mL (48.8-144.5), in febrile non-CNS infection 103.9 pg/mL (60.1-210.8), in complex febrile seizure 56 pg/mL (53.2-58.3), and in idiopathic intracranial hypertension 97.1 pg/mL (60.1-124.6). Within the meningitis group, children with Lyme neuroborreliosis (LNB) had significantly higher cNfL concentrations (median 147.9 pg/mL; range 87.8-205.4 pg/mL) than children with enterovirus meningitis (72.5 pg/mL; 58.1-95.6 pg/mL; p = 0.048) and non-significantly higher cNfL levels when compared to Bell's palsy (88.6 pg/mL; 48.8-144.5 pg/mL; p = 0.082). There was no correlation between cNfL levels and age. (4) Conclusions: Although the number of patients in this pilot study cohort is limited, higher cNfL levels in children with LNB compared to those with viral meningitis (significant) and Bell's palsy (trend) may indicate the potential of cNfL as a biomarker in the differential diagnosis of pediatric meningitis and facial palsy.