OBJECTIVE
Subclinical seizures (SCSs) remain an understudied aspect of presurgical evaluation in patients with drug-resistant epilepsy (DRE), with uncertain prevalence, distribution among epilepsy types, and predictive value for surgical outcomes. This systematic review and meta-analysis aims to explore the occurrence of SCSs, their concordance with the seizure-onset zone (SOZ), and their association with postoperative seizure outcomes.
METHODS
A systematic search of Medline, Embase, and Web of Science was performed to identify studies reporting SCSs during scalp electroencephalography (EEG) monitoring or intracranial EEG (iEEG) monitoring in patients with DRE undergoing epilepsy surgery. Data on SCS prevalence, concordance with SOZ, and postoperative outcomes were extracted. Pooled proportions and odds ratios (ORs) were estimated using random-effects generalized linear mixed models. Subgroup analyses evaluated the proportions of SCSs in temporal vs extratemporal epilepsy.
RESULTS
Thirteen studies comprising 1174 patients met the inclusion criteria. The pooled prevalence of SCSs was 32% (95% confidence interval [CI] 8-73) during scalp EEG monitoring and 50% (95% CI 38-62) during iEEG monitoring. Concordant SCSs with SOZ occurred in 37% of patients undergoing iEEG. Non-concordant SCSs were associated with a nearly fivefold higher odds of poor postoperative seizure control (OR 4.82, 95% CI 1.80-12.96; p = 0.002). SCSs were more frequent in temporal lobe epilepsy than in extratemporal epilepsy (57% vs 44%, p = 0.046). Within temporal lobe epilepsy, the highest prevalence was observed in the mesiotemporal region (69%). Overall, the presence of SCSs alone was not associated with a poor outcome, but the spatial non-concordance with the SOZ was highly predictive for poor seizure outcome.
SIGNIFICANCE
SCSs are common in presurgical evaluation, particularly in temporal lobe epilepsy. Although their presence alone is not prognostic, non-concordant SCSs are associated with worse postoperative outcomes. Systematic assessment, especially using iEEG, may improve delineation of the epileptogenic zone and surgical planning in DRE.
P. Bosque-Varela, Panagiota-Eleni Tsalouchidou, Petra Levicka et al.· Epilepsia· 0 citations
New-onset refractory status epilepticus (NORSE) is a rare, life-threatening condition occurring in individuals without prior epilepsy or acute structural, toxic, or metabolic causes. Its etiology often remains cryptogenic, and inconsistent terminology hampers early recognition and treatment. This study aims to better characterize NORSE to support faster clinical diagnosis and management. We retrospectively identified all adult patients with status epilepticus (SE) admitted to the Department of Neurology, University Hospital Marburg, Germany, between 2011 and 2023. Demographic, etiologic, treatment, and outcome data from patients fulfilling consensus criteria for NORSE were compared with those of non-NORSE patients. We additionally performed a sensitivity analysis applying strict temporal diagnostic criteria (≤ 72 h) to assess the impact of consensus-based classification on cohort definition. Of 779 patients with status epilepticus, 120 fulfilled criteria for NORSE, delineating a distinct clinical subgroup characterized by advanced age and a female predominance (67.5%, p = 0.028). Phenotypically, NORSE was strongly associated with generalized seizure semiology (70.7%, p < 0.001) and a higher burden of nonconvulsive status epilepticus (45.8%, p < 0.001), while the underlying etiology frequently remained cryptogenic (56.7%). This constellation translated into an adverse clinical trajectory, reflected by reduced rates of discharge home, increased in-hospital mortality (19.5%, p < 0.001), and greater reliance on rehabilitative care. Notably, these differences were not paralleled by alterations in metabolic indices such as HbA1c or cholesterol, underscoring the limited discriminatory value of these parameters in NORSE. Application of strict temporal criteria resulted in a smaller, more conservative NORSE cohort, while key clinical features and outcomes remained largely unchanged. NORSE defines a distinct and severe clinical syndrome within status epilepticus, characterized by older age, female predominance and adverse outcomes. Beyond the clinical severity of NORSE, our findings show that cohort composition is highly sensitive to the temporal operationalization of consensus criteria. Standardized application of diagnostic timing may therefore be essential for comparability across NORSE studies.
Clara Jünemann, Meike Menche, Marc-Philipp Bergmann et al.· Neurological Research and Pr...· 0 citations
