Editors' Note: Prediction of Regaining Consciousness Despite an Early Epileptiform EEG After Cardiac Arrest

Neuroprognostication after cardiac arrest often remains reliant on neurophysiologic and serologic testing. To better prognosticate outcomes among patients with early epileptiform activity on EEG, Dr. Barbella et al. modeled various EEG predictors of favorable outcome using updated neurophysiologic criteria. Early absence of epileptiform activity, continuous background amplitude with reactivity, and later stimulus-induced rhythmic periodic or ictal discharges (SIRPIDs) strongly predicted favorable long-term outcomes in these patients after cardiac arrest (area under the curve 0.96, 95% CI 0.91-1.00). In a reader response, Dr. Sethi highlights that SIRPIDs may indicate brain reactivity, but they are not associated with cerebral hyperperfusion (as in the case of seizures). Both the investigators and Dr. Sethi agree that later SIRPIDs need not be treated aggressively in these patients. This study adds considerably to the neuroprognostication literature by showing early epileptiform activity may not always be a poor prognostic marker after cardiac arrest. Even in the presence of epileptiform activity, some features indicate a reasonable probability of functional recovery. As the investigators note in their methods-intensive care withdrawal was considered in patients with treatment-resistant myoclonus or status epilepticus, absent somatosensory-evoked potentials, incomplete return of brainstem reflexes, and elevated neuron specific enolase levels. Unsurprisingly, each of these findings strongly predicted poor outcomes. Therefore, the high sensitivity and specificity of the NEC2RAS score for predicting poor outcome does not disentangle it from the possibility of it contributing to the self-fulfilling prophecy.

Automated summary

The study shows that early absence of epileptiform activity, continuous background amplitude with reactivity, and later stimulus-induced rhythmic periodic or ictal discharges (SIRPIDs) strongly predict favorable long-term outcomes in patients after cardiac arrest. While SIRPIDs may indicate brain reactivity, they are not associated with cerebral hyperperfusion, and therefore do not require aggressive treatment in later stages.