Prevalence of non-convulsive status epilepticus in adults presenting with altered mental status: a systematic review and meta-analysis.

BACKGROUND: Status epilepticus (SE) is any type of seizure that lasts more than five minutes or two or more seizures which occur within a five-minute period without complete inter-ictal recovery of consciousness. Non-convulsive status epilepticus (NCSE), on the other hand, is any SE that occurs without any prominent motor activities. Due to its subtle manifestation, it's often underrecognized and underdiagnosed in various populations. This systematic review with meta-analysis aimed to assess its prevalence in patients with altered mental status (AMS). METHODS: Three databases - PubMed, Cochrane Library, & ScienceDirect - were comprehensively searched for all published relevant articles. All the articles were assessed according to PRISMA guidelines, and data were extracted from the relevant articles. RESULTS: The electronic search retrieved 1907 articles from the three databases. Only 20 articles among these articles met the inclusion criteria and were thus included in the review. The articles provided data from 23,068 patients with AMS. Our systematic review found that the overall prevalence of NCSE in patients with AMS ranged from 0.1% to 49.1%. The prevalence ranged from 10.48% to 27.5% among AMS patients admitted to neurological intensive care units (NICUs) and from 8.1% to 8.8% among comatose patients. In addition, among studies reporting seizure classifications, NCSE accounted for 0.7% to 1.4% of all seizures and 46.9% of status epilepticus cases. CONCLUSION: This review found NCSE to occur in a substantial proportion of patients with AMS. However, most current studies are small-scale cohort studies with limited power to determine the prevalence of NCSE. Well-designed large-scale cohort studies are therefore recommended for the accuracy in the estimated prevalence of NCSE in these patients.