Serum and CSF neurofilament light chain levels in antibody-mediated encephalitis

Circulating and cerebrospinal fluid (CSF) neurofilament light chain (NfL) levels represent a reliable indicator of disease activity and axonal damage in different neuroinflammatory conditions. Recently, high CSF NfL levels have been detected in active autoimmune encephalitis, as opposed to significant lower levels after clinical improvement. The aim of the present study was to evaluate serum and CSF NfL concentration in patients with autoimmune encephalitis and to analyse the association between NfL levels and clinical, MRI, and CSF data. We retrospectively included 25 patients with neurological syndromes associated with autoantibodies to neuronal cell surface antigens and we collected clinical, MRI, CSF, and follow-up data. Using an ultrasensitive method (Simoa, Quanterix), we measured NfL levels in serum and CSF samples of all patients and in 25 sera of healthy controls. Serum NfL levels were higher in all cases, including 20 patients with inflammatory MRI/CSF features and 5 non-inflammatory cases (median 16.9 pg/ml, range 4.5–90) than in controls (median 6.9 pg/ml, range 2.7–12.8; p