Clinical risk factors for non-convulsive status epilepticus during emergent electroencephalogram

Abstract

Purpose: Emergent electroencephalograms (EmEEG) are performed to exclude non-convulsive status epilepticus (NCSE) but are resource-intensive. Prior studies have identified a seizure or seizures in the acute setting preceding the EmEEG request as a risk factor of NCSE but few other consistent clinical risk factors have been identified. We aimed to identify clinical risk factors for NCSE in EmEEGs

Methods: We conducted a retrospective analysis of consecutive patients who underwent EmEEG to exclude NCSE over a 20-month period. One blinded investigator extracted clinical information from patient case records using a standardized form. Patients were grouped using EmEEG results into those with and without NCSE. We analyzed differences between these two groups.

Results: A total of 2333 EEGs were performed over the study period, 215 (9.3%) were EmEEGs ordered to exclude NCSE. 21 patients (9.8%) of the 215 patients were found to have NCSE. Three independent clinical risk factors for NCSE were identified--seizure(s) in the acute setting, ocular movements (nystagmus and/or gaze deviation) and ongoing CNS infection. The presence of seizure(s) in the acute setting showed the highest adjusted odds ratio (OR=8.8, 95% CI 2.0-39.4, p=0.005). In addition, prevalence of NCSE increased as more clinical risk factors were present.

Conclusion: Seizures in the acute setting, ocular movements and ongoing CNS infection are associated with NCSE. By using these risk factors at the bedside, clinicians can prioritize patients for EmEEG, recognizing that risk of NCSE increases as more clinical risk factors are present.

Keywords: Clinical Risk factors; Emergent Electroencephalogram; Non-convulsive status epilepticus.