Postanoxic electrographic status epilepticus and serum biomarkers of brain injury

Aim: To explore if electrographic status epilepticus (ESE) after cardiac arrest causes additional secondary brain injury reflected by serum levels of two novel biomarkers of brain injury: neurofilament light chain (NfL) originating from neurons and glial fibrillary acidic protein (GFAP) from glial cells. Methods: Simplified continuous EEG (cEEG) and serum levels of NfL and GFAP, sampled at 24, 48 and 72 hours after cardiac arrest, were collected during the Target Temperature Management (TTM)-trial. Two statistical methods were used: multivariable regresssion analysis; and a matched control group of patients without ESE matched for early predictors of poor neurological outcome. Results: 128 patients had available biomarkers and cEEG. Twenty-six (20%) patients developed ESE, the majority (69%) within 24 hours. ESE was an independent predictor of elevated serum NfL (p < 0.001) but not of serum GFAP (p = 0.16) at 72 hours after cardiac arrest. Compared to a control group matched for early predictors of poor neurological outcome, patients who developed ESE had higher levels of serum NfL (p = 0.03) and GFAP (p = 0.04) at 72 hours after cardiac arrest. Conclusion: ESE after cardiac arrest is associated with higher levels of serum NfL which may suggest increased secondary neuronal injury compared to matched patients without ESE but similar initial brain injury. Associations with GFAP reflecting glial injury are less clear. The study design cannot exclude imperfect matching or other mechanisms of secondary brain injury contributing to the higher levels of biomarkers of brain injury seen in the patients with ESE.