Nonconvulsive and Electrographic Status Epilepticus in Comatose Adult Survivors of Cardiac Arrest: A Systematic Review and Meta-Analysis of Prevalence, EEG-Based Diagnosis, Treatment, and Neurological Outcomes.

Objectives: This systematic review and meta-analysis aimed to estimate the prevalence of nonconvulsive status epilepticus (NCSE), electrographic status epilepticus (ESE), post-anoxic status epilepticus (PSE), and electrographic seizures in comatose adult survivors of cardiac arrest and to summarize associated diagnostic approaches, treatment strategies, neurological outcomes, and mortality. Methods: PubMed/MEDLINE, MEDLINE Core, Cochrane CENTRAL, Web of Science, and Scopus were searched from inception to May 2026. Eligible studies included adult comatose survivors of cardiac arrest who underwent EEG monitoring and reported NCSE, ESE, PSE, electrographic seizures, or related rhythmic/periodic EEG patterns. Random-effects meta-analysis of proportions was performed, separating strict NCSE/ESE/PSE constructs from broader electrographic seizure/status and epileptiform/IIC constructs. Results: Seventeen studies were included. In the primary analysis of four non-overlapping EEG-monitored cohorts, strict NCSE/ESE/PSE occurred in 112 of 457 patients; the pooled prevalence was 22% (95% CI, 10-41%; 95% prediction interval, 4-64%; I2 = 77.8%). The expanded sensitivity analysis including selected, historical, or restricted cohorts yielded a similar pooled prevalence of 22% (95% CI, 16-31%). Broad electrographic seizure/status prevalence was 10% (95% CI, 2-33%; I2 = 94.7%), and broad epileptiform/ictal-interictal continuum pattern prevalence was 29% (95% CI, 7-70%; I2 = 86.0%); these analyses represented distinct EEG constructs. Poor neurological outcome and mortality were frequent, with pooled estimates of 91% (95% CI, 85-94%) and 87% (95% CI, 78-93%), respectively. Conclusions: The pooled prevalence of NCSE/ESE/PSE was 22% among EEG-monitored comatose survivors of cardiac arrest, although the exact prevalence remains uncertain across settings. Poor neurological outcome and mortality were frequent, but recovery occurred in selected patients with continuous EEG background, later SE onset, fewer multimodal poor-outcome markers, or electrographic cessation. These findings support multimodal, phenotype-guided interpretation rather than reliance on EEG status alone. Future studies should use standardized EEG definitions, consistent denominators, and phenotype-enriched randomized designs.