Postoperative epileptiform discharges predict seizure outcomes in pediatric low-grade developmental and epilepsy associated tumors.

Background and Purpose:This study aimed to determine whether preoperative or postoperative electroencephalography (EEG) can predict surgical outcome for corpus callosotomy.Methods:We retrospectively reviewed the medical records of 16 patients enrolled. We compared postoperative seizure outcome according to seizure type, preoperative interictal EEG, preoperative ictal EEG, and postoperative interictal EEG. Seizure outcome was classified according to postoperative seizure reduction, i.e., seizure free, >90%, 50–90%, <50%, and no change or worsened. A seizure reduction of 50% or more was judged as a “favorable outcome”.Results:Most patients showed a favorable outcome (12 patients, 75%) and two patients became seizure free (13%). Atonic seizure was most responsive to corpus callosotomy. Preoperative interictal epileptiform discharge had 3 patterns; bilateral independent, generalized, and combination of independent and generalized. None of the preoperative interictal epileptiform discharge (EDs) had significant correlation with seizure outcome. The preoperative ictal rhythm did not predict seizure outcome. However disappearance of generalized EDs on postoperative EEG was correlated with favorable seizure outcome.Conclusions:The presence of generalized EDs on postoperative interictal EEG predicted seizure outcome, whereas preoperative EEG did not.

To determine whether EEG performed within few months after epilepsy surgery is predictive of seizure outcome, 58 consecutive patients undergoing surgery for presumptive temporal lobe epilepsy (TLE) who had clinical follow-up of at least 2 years and EEG data available both pre- and postoperatively were analyzed. Patients were classified by preoperative brain magnetic resonance imaging into lesional, cryptogenic, and hippocampal sclerosis groups. Seizure outcome was classified according to Engel's outcome scale. Comparison was made between the presence of interictal epileptiform discharges (IEDs) in the postoperative EEG and seizure outcome. Patients who experienced seizures within 2 months after surgery were considered to have early recurrence. The mean follow-up period was 3 years. Sixty percent of patients achieved a class I seizure outcome. Almost all (95%) postoperative EEGs were obtained within 4 months after surgery. IEDs were present in 26% of postoperative EEGs, but were significantly less frequent in EEGs recorded after the first two postoperative months (P = 0.011). The presence of IEDs on postoperative EEGs was not predictive of seizure outcome either in the whole cohort or in any of the subgroups, regardless of whether it was performed within or after the first two postoperative months. It was also not predictive of outcome in the 44 patients (76%) who did not suffer early recurrence. The authors conclude that EEG performed a few months after epilepsy surgery is not useful as a predictor of long-term seizure outcome.

Prognostic Value of Preoperative and Postoperative Electroencephalography Findings in Pediatric Patients Undergoing Hemispheric Epilepsy Surgery

To characterize seizure and cognitive outcomes of sparing vs removing an magnetic resonance imaging (MRI)-normal hippocampus in patients with temporal lobe epilepsy. In this retrospective cohort study, we reviewed clinical, imaging, surgical, and histopathological data on 152 individuals with temporal lobe epilepsy and nonlesional hippocampi categorized into hippocampus-spared (n=74) or hippocampus-resected (n=78). Extra-hippocampal lesions were allowed. Pre- and postoperative cognitive data were available on 86 patients. Predictors of seizure and cognitive outcomes were identified using Cox-proportional hazard modeling followed by treatment-specific model reduction according to Akaike information criterion, and built into an online risk calculator. Seizures recurred in 40% within one postoperative year, and in 63% within six postoperative years. Male gender (P=.03), longer epilepsy duration (P<.01), normal MRI (P=.04), invasive evaluation (P=.02), and acute postoperative seizures (P<.01) were associated with a higher risk of recurrence. We found no significant difference in postoperative seizure freedom rates at 5years between those whose hippocampus was spared and those whose hippocampus was resected (P=.17). Seizure outcome models built with pre- and postoperative data had bootstrap validated concordance indices of 0.65 and 0.72. The dominant hippocampus-spared group had lower rates of decline in verbal memory (39% vs 70%; P=.03) and naming (41% vs 79%; P=.01) compared to the hippocampus-resected group. Partial hippocampus sparing had the same risk of verbal memory decline as for complete removal. Sparing or removing an MRI-normal hippocampus yielded similar long-term seizure outcome. A more conservative approach, sparing the hippocampus, only partially shields patients from postoperative cognitive deficits. Risk calculators are provided to facilitate clinical counseling.

Early resective surgery causes favorable seizure outcome in malformations of cortical development

To describe the histologic spectrum and clinical characteristics of patients with neuroepithelial tumors and drug-resistant epilepsy and to analyze clinical data and treatment related to seizure outcome and survival. Data were analyzed from 207 consecutive patients with intractable epilepsy (aged 2-54 years), who between 1988 and 1999 had >or=50% resection of supratentorial, neuroepithelial tumors. Extent of resection was assessed on postoperative magnetic resonance imaging (MRI); seizure outcome was classified according to Engel's outcome scale; and follow-up data were prospectively updated. Median follow-up was eight years (range, 2-14 years). Histologic examination revealed 154 classic epilepsy-associated tumors (ganglioglioma, dysembryoplastic neuroepithelial tumor, pleomorphic xanthoastrocytoma, and pilocytic astrocytomas) and 53 others (astrocytomas and oligodendrogliomas). Four World Health Organization (WHO) grade III tumors were found (astrocytoma, n = 3; ganglioglioma, n = 1). After surgery, 82% of the patients were seizure free (class I). The following factors were associated with improved seizure outcome: Short duration of epilepsy before surgery, single EEG focus, absence of additional hippocampal sclerosis or cortical dysplasia, transsylvian approach, other than astrocytomas, and complete tumor resection. After 5 years, only nine (4%) patients had tumor recurrence, four (2%) with malignant transformation and death. None of the four patients with anaplastic tumors died. Even patients with astrocytomas of WHO grade II or III showed 10-year recurrence of only 25% and 10-year survival of 90%. Tumors associated with long-term epilepsy should be removed early for two different reasons: high rate of seizure freedom and rare but potential risk of malignant tumor progression. The unexpected long survival of these astrocytomas should be investigated by using immunohistochemistry and molecular biology.

Serial postoperative awake and sleep EEG and long-term seizure outcome after anterior temporal lobectomy for hippocampal sclerosis

Prognostic significance of postoperative spikes varied in different surgical procedures for mesial temporal sclerosis

Diffuse low grade glioma after the 2016 WHO update, seizure characteristics, imaging correlates and outcomes

Compared with temporal or frontal resections, epilepsy surgery in the posterior cortex is rarely performed, and the literature concerning clinical predictors for the postoperative seizure outcome in this particular subgroup is sparse. The data of 42 patients with lesional focal epilepsies of the parieto-occipital lobe and the occipital border of the temporal lobe were evaluated retrospectively and related to the seizure outcome 2 years after epilepsy surgery. The investigated parameters included ictal semiology, pre- and postoperative EEG and neuroimaging, histological findings and demographic data. Postoperatively, seizure-free outcome was seen in: (i) 69% of patients with lateralizing auras, but only in 28% of patients without lateralizing auras (P = 0.01); and (ii) 57% of the patients with lateralizing seizures, but only in 17% of patients without lateralizing ictal semiology (P = 0.02). None of the patients with neither lateralizing auras nor lateralizing seizures achieved freedom from seizures (P < 0.01). The proportion of lateralizing seizures (P < 0.01) and auras (P = 0.02) in the total number of recorded seizures and auras was significantly related to the probability of a favourable surgical outcome. No patient with clinical lateralizing signs to the non-lesional hemisphere but 58% without such "false" lateralization achieved freedom from seizures (P = 0.02). The following parameters also proved to be predictive for a favourable seizure outcome: (i) tumoural aetiology; and (ii) absence of epileptiform discharges in the postoperative EEG. The presence and frequency of ictal semiology lateralizing to the lesional hemisphere and the absence of lateralizing signs to the non-lesional hemisphere are highly predictive of a favourable outcome after surgical treatment of epilepsy in the posterior cortex.

Corpus callosotomy: A palliative therapeutic technique may help identify resectable epileptogenic foci

Background: Low-grade epilepsy-associated brain tumors (LEATs) are found to be the second most common lesion-related epilepsy. Malignant potential of LEATs is very low and the overall survival is good, so the focus of treatment is focused more on seizure outcome rather than oncological prognosis. Objectives: This study was conducted to evaluate the risk factors of seizure outcomes after resection in patients with LEATs. Design: A retrospective study. Methods: A retrospective analysis of patients with LEATs who underwent resective surgery in our three epilepsy centers between October 2010 and April 2023 with a minimum follow-up of 1 year. Demography, clinical characters, neurophysiology, and molecular neuropathology were assessed for association with postoperative seizure outcomes at 1-, 2-, and 5-year follow-up. Synthetic minority oversampling technique (SMOTE) algorithm model was performed to handle the imbalance of data distribution. Gaussian Naïve Bayes (GNB) algorithms were created as a basis for classifying outcomes according to observation indicators. Results: A total of 111 patients were enrolled in the cohort. The most common pathology was ganglioglioma ( n = 37, 33.3%). The percentage of patients with seizure freedom was 91.0% (101/111) at 1-year follow-up, 87.5% (77/88) at 2-year follow-up, and 79.1% (53/67) at 5-year follow-up. Partial resection had a significantly poor seizure outcome compared to total resection and supratotal resection ( p &lt; 0.05). The epileptiform discharge on post-resective intraoperative electrocorticography (ECoG) or postoperative scalp electroencephalography (EEG) were negative factors on postoperative seizure freedom at 1-, 2-, or 5-year follow-ups ( p &lt; 0.05). The area under the receiver-operating characteristic curve value of the GNB-SMOTE model was 0.95 (95% CI, 0.876–1.000), 0.892 (95% CI, 0.656–0.934), and 0.786 (95% CI, 0.491–0.937) at 1-, 2-, and 5-year follow-up, respectively. Conclusion: The partial resection, post-resective intraoperative ECoG, and postoperative scalp EEG were valuable indicators of poor seizure outcomes. The utilization of post-resective intraoperative ECoG is beneficial to improve seizure outcomes. Based on the data diversity and completeness of three medical centers, a multivariate correlation analysis model was established based on GNB algorithm.

Prognostic significance of serial postoperative EEG in extratemporal lobe epilepsy surgery

ObjectivesSeizures are a common presenting symptom in patients with low grade glioma (LGG). Exact mechanisms of epileptogenesis are unknown and the influence of radiological and histological characteristics are not well studied, particularly after the 2016 WHO reclassification of gliomas. We aimed to define predictors of seizure development and outcome in patients with LGG.DesignRetrospective single institution case series.Subjects63 patients who underwent resection of supratentorial LGG in a single institution, 45 presented with seizures.MethodsRetrospective analysis of patient records to assess seizure outcome and other demographics including radiological variables, tumour characteristics, type of surgery and histology based on the 2016 WHO update.ResultsAfter surgery, 33 patients (73%) who presented with seizures were Engel class I at median follow up of 43 months. Complete and near total resection were associated with improved Engel class compared to subtotal resection. Awake craniotomy gave improved seizure outcomes compared to under general anaesthesia (84% vs 65%). Molecular genetics did not predict seizure outcome. Updated histology did not predict seizures at diagnosis, only tumour heterogeneousity on initial MRI (p=0.043). Tumour volume at presentation impacted EOR but not seizure outcome.ConclusionsSeizure outcome is directly related to EOR. Tumour histology based on molecular genetics did not predict seizure development or outcome. Use of awake craniotomy results in greater EOR and improved Engel class.

Focal cortical dysplasia (FCD) is a common cause of early-onset intractable epilepsy, and resection is a highly sufficient treatment option. In this study, the authors aimed to provide a retrospective analysis of pre- and postoperative factors and their impact on postoperative long-term seizure outcome. The postoperative seizure outcomes of 50 patients with a mean age of 8 ± 4.49 years and histologically proven FCD type II were retrospectively analyzed. Furthermore, pre- and postoperative predictors of long-term seizure freedom were assessed. The seizure outcome was evaluated based on the International League Against Epilepsy (ILAE) classification. Complete resection of FCD according to MRI criteria was achieved in 74% (n = 37) of patients. ILAE class 1 at the last follow-up was achieved in 76% (n = 38) of patients. A reduction of antiepileptic drugs (AEDs) to monotherapy or complete withdrawal was achieved in 60% (n = 30) of patients. Twelve patients (24%) had a late seizure recurrence, 50% (n = 6) of which occurred after reduction of AEDs. A lower number of AEDs prior to surgery significantly predicted a favorable seizure outcome (p = 0.013, HR 7.63). Furthermore, younger age at the time of surgery, shorter duration of epilepsy prior to surgery, and complete resection were positive predictors for long-term seizure freedom. The duration of epilepsy, completeness of resection, number of AEDs prior to surgery, and younger age at the time of surgery served as predictors of postoperative long-term seizure outcome, and, as such, may improve clinical practice when selecting and counseling appropriate candidates for resective epilepsy surgery. The study results also underscored that epilepsy surgery should be considered early in the disease course of pediatric patients with FCD type II.