Neurofilament-light (NfL) chain is emerging as an important biomarker of neuroaxonal injury in multiple sclerosis, Alzheimer disease, spinal cord injury and other neurological disorders, but has been less studied in epilepsy.

A new study examined serum levels of NfL in 204 patients with epilepsy (Akel et al. Epilepsia 2023;64:2690-2700). Biomarker levels were also compared in patients with seizures in the preceding two months versus those who were seizure-free for >1 year. A total of 27 patients (13%) had abnormally high sNfL concentrations. Elevated sNfL was associated with recent seizures and radiologic evidence of epileptogenic lesions. NfL was weakly correlated with the number of days since the last seizure, and with seizure frequency in the preceding two months.

A separate study found that sNfL was generally not elevated in patients with epilepsy (Ueda et al. Epileptic Disord 2023;25:229-236). However, sNfL level was correlated with cognitive test scores, suggesting that it may be a biomarker of cognitive function in epilepsy patients.

In a pediatric cohort, no significant elevation in NfL was shown in patients with epileptic seizures or febrile seizures compared to healthy controls (Geis et al. Eur J Paediatr Neurol 2023;45:9-13). Overall, mean sNfL levels decreased 3.2% from birth to age 12, then increased 2.7% per year during adolescence.

The prognostic value of sNfL has been studied most extensively in status epilepticus (SE). An Italian retrospective study reported higher sNfL levels in SE patients compared to drug-resistant epilepsy patients (median 26.15 vs. 7.35 pg/mL) (Giovannini et al. Epilepsia 2022;63:e23-e29). An sNfL level >28.8 pg/mL was predictive of 30-day clinical worsening or death (odds ratio 10.83).

Also noteworthy was a German study that found elevated sNfL concentrations in patients with non-convulsive SE as well as in convulsive SE (Margraf et al. J Neurol 2023;270:2128-2138). The main factor affecting sNfL was the duration of SE. sNfL was not associated with treatment refractoriness or prognostic scores. The authors concluded that both convulsive and non-convulsive SE are similarly urgent neurological emergencies associated with neuroaxonal damage.