Late electroencephalographic seizure‐risk findings and restricted diffusion on magnetic resonance imaging as seizure‐burden markers associated with neurological deficits after status epilepticus in a remote or chronic cohort

Abstract Objective To evaluate whether time‐dependent electroencephalographic (EEG) seizure risk findings and restricted diffusion on magnetic resonance imaging (MRI) are associated with neurological outcomes after status epilepticus (SE), beyond seizure duration. Methods This two‐center observational study included consecutive SE patients from 2017 to 2025. We examined three seizure‐related markers: seizure duration ≥ 30 min, a 2HELPS2B score ≥ 2 on a late EEG (performed the following day or later after SE onset), and SE‐related restricted diffusion on MRI (peri‐ictal diffusion‐weighted imaging hyperintensity with reduced apparent diffusion coefficient values). Outcomes were overall neurological worsening and SE‐attributable focal neurological deficits at discharge. Multivariable models included the three markers and age> 65 years, with further adjustment for stupor or coma at admission and third‐line therapy. Results Of 440 patients with suspected SE, 297 had confirmed SE; 221 with an identified seizure focus formed the overall cohort; 127 with remote symptomatic SE or preexisting chronic focal epilepsy formed the remote or chronic cohort. Overall neurological worsening occurred in 96 patients (43.4%) and SE‐attributable focal neurological deficits in 68 (30.8%). In univariable analyses, seizure duration ≥ 30 min was associated with both outcomes in the overall cohort. A 2HELPS2B score ≥ 2 on late EEG was associated with both outcomes in both cohorts, whereas high‐risk findings on early EEG were not. In multivariable models including seizure duration, restricted diffusion was independently associated with both outcomes in both cohorts, most strongly with focal neurological deficits in the remote or chronic cohort (adjusted odds ratio [OR] = 28.59, 95% confidence interval [CI] = 7.23–154.99). A 2HELPS2B score ≥ 2 on late EEG was independently associated with focal neurological deficits in the remote or chronic cohort (adjusted OR = 4.26, 95% CI = 1.35–14.24), whereas seizure duration ≥ 30 min was not independently associated with either outcome. Significance High‐risk late‐EEG findings and restricted diffusion were associated with neurological deficits. These markers may complement seizure duration in estimating cumulative seizure burden and focal brain injury.