Characteristics of electroencephalographic changes after hemispheric disconnection surgery in patients with drug-resistant epilepsy

Electroclinical features and dynamic network connectivity of orbitofrontal epilepsy.

OBJECTIVE Orbitofrontal epilepsy (OFE) is rare and underrecognized. This study aims to characterize electroclinical features and dynamic network connectivity of OFE and subtypes. METHODS We retrospectively analyzed 17 patients with OFE who underwent stereoelectroencephalographic (SEEG) electrode implantation and epilepsy surgery at our center. Thirteen patients with available ictal SEEG recordings were further categorized into lateral (LOFE, n = 6), medial (MOFE, n = 5), and posterior (POFE, n = 2) subtypes. Clinical semiology, scalp electroencephalographic (EEG), neuroimaging, and SEEG data were analyzed. Directed functional connectivity was evaluated in 22 seizures from 13 patients using pairwise nonlinear regression across ictal stages. RESULTS The mean seizure duration was 68.4 s. Semiology was heterogeneous, with impaired consciousness being the most common manifestation (47.1%), frequently evolving into elementary motor phenomena (62.5%) or automatisms (37.5%). Hyperkinetic behavior (23.5%) and focal to bilateral tonic-clonic seizures (29.4%) were also observed. This heterogeneity may relate to propagation to frontal, cingulate, insular, and temporal regions. In 13 patients with available ictal SEEG recordings, EEG seizure activity preceded clinical onset, with a mean electroclinical delay of 28.9 s. LOFE most often showed nonspecific auras and early motor manifestations; MOFE was associated with autonomic auras and automatisms; and POFE frequently presented with fear auras. Functional connectivity increased from early to late ictal periods and remained elevated postictally. Connectivity differences between LOFE and MOFE were confined to the seizure onset and early propagation phases, with LOFE showing stronger lateral frontal interactions and MOFE stronger medial frontal-cingulate/insula interactions. SEEG resolved frequent mislocalizations by scalp EEG/imaging. Most patients achieved favorable outcomes (Engel class I: 84.6%, mean follow-up = 52.1 months, 11/13), and focal cortical dysplasia was the most common pathology (76.9%, 10/13). SIGNIFICANCE OFE subtypes tend to show different semiological features and preferential connectivity patterns, potentially related to differential engagement of frontal-limbic networks. Targeted SEEG is associated with accurate localization and generally favorable outcomes in this cohort.

Beyond seizures: understanding adaptive functioning in drug-resistant epilepsy in patients undergoing palliative surgery

Palliative surgical procedures for pediatric DRE are safe and associated with seizure reduction, decreased medication burden, and gradual improvement in adaptive functioning and early surgical intervention may help minimize developmental decline and improve long-term adaptive outcomes.

Long-term prognostic value of early post-operative electroencephalogram in patients with drug-resistant temporal lobe epilepsy associated with hippocampal sclerosis.

High-frequency IEDs on early postoperative EEG may identify patients at increased risk of long-term deterioration after surgery for HS-related TLE, and prospective studies are needed before modifying routine follow-up strategies.

strategy for temporal lobe epilepsy with dual pathology and incomplete evidence from EEG and neuroimaging

PERSONALIZED ALGORITHM FOR PRESURGICAL STRATIFICATION OF PATIENTS WITH DRUG-RESISTANT FOCAL EPILEPSY

Drug-resistant focal epilepsy remains one of the most challenging problems in modern epileptology and functional neurosurgery, since delayed referral for presurgical evaluation increases the duration of uncontrolled seizures, worsens quality of life, and may reduce the likelihood of a favorable surgical outcome. A prospective single-center observational study was conducted and included 86 patients examined at a specialized epileptology and neurosurgical center. All patients underwent clinical and semiological seizure analysis, brain MRI, routine EEG, long-term video-EEG monitoring, neurological assessment, and neuropsychological evaluation. The stratification criteria included the presence of a structural lesion on MRI, localized seizure onset, concordance of seizure semiology with the presumed epileptogenic zone, local epileptiform activity, MRI/EEG concordance, seizure frequency, secondary bilateral tonic-clonic generalization, progressive cognitive decline, and the functional significance of the presumed intervention zone. Based on the total clinical and diagnostic score, patients were divided into low, intermediate, and high surgical eligibility groups. High surgical eligibility was identified in 29 patients, intermediate eligibility in 36, and low eligibility in 21. The most significant factors associated with the possibility of localizing the epileptogenic zone were an MRI-positive structural lesion, local ictal or interictal onset on video-EEG, concordance of clinical semiology with the presumed anatomical zone, and MRI/EEG concordance. The proposed algorithm may be used as an accessible model for primary stratification of patients requiring standard follow-up, extended presurgical evaluation, or discussion of invasive monitoring.

The association between the degree of intraoperative bisynchronization blockade and drop attack freedom after corpus callosotomy in pediatric patients: a comparative cohort study.

OBJECTIVE The aim of this study was to evaluate the prognostic value of intraoperative EEG during corpus callosotomy (CC) in pediatric patients with drug-resistant epilepsy (DRE), with a particular focus on bisynchronization blockade and its correlation with long-term seizure outcomes. METHODS A retrospective review was performed of pediatric patients with DRE and injurious drop attacks who underwent CC between 2005 and 2024. Patients were stratified into three groups based on intraoperative scalp EEG findings: 1) > 50% bisynchronization blockade, 2) < 50% blockade, and 3) absent bisynchronization. Baseline clinical characteristics, surgical approach, and extent of CC were recorded. Seizure outcomes were assessed using Engel and International League Against Epilepsy (ILAE) classifications with a minimum follow-up of 1 year. Whether atonic seizures resolved postoperatively was also evaluated. Group comparisons were performed using Fisher's exact test and Kruskal-Wallis rank-sum testing. RESULTS Forty-six patients met the inclusion criteria. The majority underwent complete CC (65%), most via an open approach (67%). At 1 year, freedom from atonic seizures (ILAE class 1Engel class I) was highest in the > 50% blockade group (70.0%) compared with the < 50% blockade (40.0%) and absent bisynchronization (25%) groups (p = 0.042). At last follow-up (mean 5.3 years), the > 50% blockade group similarly achieved significantly higher rates of atonic seizure freedom (ILAE class 1/Engel class I, 76%) compared with 0% in the < 50% blockade and 25% in the absent bisynchronization groups (p < 0.001). Outcomes for total seizure freedom varied and did not reach statistical significance between groups. CONCLUSIONS Achieving > 50% intraoperative bisynchronization blockade during CC was strongly associated with improved long-term atonic seizure freedom. These findings support the role of intraoperative EEG as a prognostic marker of effective seizure control.