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Objective: Electrical stimulation mapping (ESM) is the clinical standard for functional localization with subdural electrodes (SDE). As stereoelectroencephalography (SEEG) has emerged as an alternative option, we compared functional responses, afterdischarges (ADs), and unwanted ESM‐induced seizures (EISs) between the two electrode types. Methods: Incidence and current thresholds for functional responses (sensory, motor, speech/language), ADs, and EISs were compared between SDE and SEEG using mixed models incorporating relevant covariates. Results: We identified 67 SEEG ESM and 106 SDE ESM patients (7207 and 4980 stimulated contacts, respectively). We found similar incidence of language and motor responses between electrode types; however, more SEEG patients reported sensory responses. ADs and EISs occurred less commonly with SEEG than SDE. Current thresholds for language, face motor, and upper extremity (UE) motor responses and EIS significantly decreased with age. However, they were not affected by electrode type, premedication, or dominant hemispheric stimulation. AD thresholds were higher with SEEG than with SDE. For SEEG ESM, language thresholds remained below AD thresholds up to 26 years of age, whereas this relationship was inverse for SDE. Also, face and UE motor thresholds fell below AD thresholds at earlier ages for SEEG than SDE. AD and EIS thresholds were not affected by premedication. Significance: SEEG and SDE have clinically relevant differences for functional brain mapping with electrical stimulation. Although evaluation of language and motor regions is comparable between SEEG and SDE, SEEG offers a higher likelihood of identifying sensory areas. A lower incidence of ADs and EISs, and a favorable relationship between functional and AD thresholds suggest superior safety and neurophysiologic validity for SEEG ESM than SDE ESM. [ABSTRACT FROM AUTHOR]

Objective: Seizures are known to occur with diurnal and other rhythms. To gain insight into the neurophysiology of periodicity of seizures, we tested the hypothesis that intracranial high-frequency oscillations (HFOs) show diurnal rhythms and sleep-wake cycle variation. We further hypothesized that HFOs have different rhythms within and outside the seizure-onset zone (SOZ).Methods: In drug-resistant epilepsy patients undergoing stereotactic-EEG (SEEG) monitoring to localize SOZ, we analyzed the number of 50-200 Hz HFOs/channel/minute (HFO density) through a 24-hour period. The distribution of HFO density during the 24-hour period as a function of the clock time was analyzed with cosinor model, and for non-uniformity with the sleep-wake cycle.Results: HFO density showed a significant diurnal rhythm overall and both within and outside SOZ. This diurnal rhythm of HFO density showed significantly lower amplitude and longer acrophase within SOZ compared to outside SOZ. The peaks of difference in HFO density within and outside SOZ preceded the seizures by approximately 4 hours. The difference in HFO density within and outside SOZ also showed a non-uniform distribution as a function of sleep-wake cycle, with peaks at first hour after arousal and ±2 hours around sleep onset.Conclusions: Our study shows that the diurnal rhythm of intracranial HFOs is more robust outside the SOZ. This suggests cortical tissue within SOZ generates HFOs relatively more uniformly throughout the day with attenuation of expected diurnal rhythm. The difference in HFO density within and outside SOZ also showed non-uniform distribution according to clock times and the sleep-wake cycle, which can be a potential biomarker for preferential times of pathological cortical excitability. A temporal correlation with seizure occurrence further substantiates this hypothesis. [ABSTRACT FROM AUTHOR]

Summary: Objective: This prospective study compared the topography of high‐gamma modulation (HGM) during a story‐listening task requiring negligible patient cooperation, with the conventional electrical stimulation mapping (ESM) using a picture‐naming task, for presurgical language localization in pediatric drug‐resistant epilepsy. Methods: Patients undergoing extraoperative monitoring with subdural electrodes were included. Electrocorticographic signals were recorded during quiet baseline and a story‐listening task. The likelihood of 70‐ to 150‐Hz power modulation during the listening task relative to the baseline was estimated for each electrode and plotted on a cortical surface model. Sensitivity, specificity, accuracy, and diagnostic odds ratio (DOR) were estimated compared to ESM, using a meta‐analytic framework. Results: Nineteen patients (10 with left hemisphere electrodes) aged 4‐19 years were analyzed. HGM during story listening was observed in bilateral posterior superior temporal, angular, supramarginal, and inferior frontal gyri, along with anatomically defined language association areas. Compared to either cognitive or both cognitive and orofacial sensorimotor interference with naming during ESM, left hemisphere HGM showed high specificity (0.82‐0.84), good accuracy (0.66‐0.70), and DOR of 2.23 and 3.24, respectively. HGM was a better classifier of ESM language sites in the left temporoparietal cortex compared to the frontal lobe. Incorporating visual naming with the story‐listening task substantially improved the accuracy (0.80) and DOR (13.61) of HGM mapping, while the high specificity (0.85) was retained. In the right hemisphere, no ESM sites for aphasia were seen, and the results of HGM and ESM comparisons were not significant. Significance: HGM associated with story listening is a specific determinant of left hemisphere ESM language sites. It can be used for presurgical language mapping in children who cannot cooperate with conventional language tasks requiring active engagement. Incorporation of additional language tasks, if feasible, can further improve the diagnostic accuracy of language localization with HGM. [ABSTRACT FROM AUTHOR]

Purpose: Lack of a potentially epileptogenic lesion on brain magnetic resonance imaging (MRI) is a poor prognostic marker for epilepsy surgery. We present a single-center series of childhood-onset MRI-negative drug-resistant epilepsy (DRE) and analyze surgical outcomes and predictors.Methods: Children with MRI-negative DRE who had resective surgery from January 2007 to December 2013 were identified using an institutional database. Relevant clinical, neurophysiological, imaging, and surgical data was extracted. The primary outcome measure was seizure freedom. Predictors of seizure freedom were obtained using multivariate logistic regression.Results: Out of 47 children with MRI-negative DRE, 12 (25.5%) were seizure free (International League Against Epilepsy [ILAE] outcome class I), after mean follow-up of 2.75 (±1.72) years. Seizure-free proportion was significantly higher in patients with single seizure semiology and concordant ictal EEG (50.0% vs. 15.2%, p=0.025). Multivariate analysis using only non-invasive pre-surgical data showed that children with daily seizures (OR 0.02, 95% CI<0.001-0.55), and earlier onset of seizures (OR 0.72, 95% CI 0.52-0.99) were less likely to be seizure-free. Also, each additional anti-epileptic drug (AED) tried before surgery decreased the probability of seizure-free outcome (OR 0.16, 95% CI 0.04-0.63). Repeat multivariate analysis after including surgical variables found no additional significant predictors of seizure-freedom. Cortical dysplasia (ILAE type IB) was the commonest histopathology.Conclusion: Surgical outcomes in children with MRI-negative DRE are determined by clinical factors including seizure frequency, age of onset of seizures, and number of failed AEDs. [ABSTRACT FROM AUTHOR]

• Stimulation within auditory cortex produced facial expressions and perioral motor responses in approximately one-third of patients. • Cortical sites with motor and language responses within transverse temporal gyrus and adjacent cortex (TGG+) showed different yet overlapping neurophysiologic characteristics. • TTG+ likely participates in non-verbal responses to low-level auditory and/or emotional cues during a communicative discourse. We investigated the role of transverse temporal gyrus and adjacent cortex (TTG+) in facial expressions and perioral movements. In 31 patients undergoing stereo-electroencephalography monitoring, we describe behavioral responses elicited by electrical stimulation within the TTG+. Task-induced high-gamma modulation (HGM), auditory evoked responses, and resting-state connectivity were used to investigate the cortical sites having different types of responses on electrical stimulation. Changes in facial expressions and perioral movements were elicited on electrical stimulation within TTG+ in 9 (29%) and 10 (32%) patients, respectively, in addition to the more common language responses (naming interruptions, auditory hallucinations, paraphasic errors). All functional sites showed auditory task induced HGM and evoked responses validating their location within the auditory cortex, however, motor sites showed lower peak amplitudes and longer peak latencies compared to language sites. Significant first-degree connections for motor sites included precentral, anterior cingulate, parahippocampal, and anterior insular gyri, whereas those for language sites included posterior superior temporal, posterior middle temporal, inferior frontal, supramarginal, and angular gyri. Multimodal data suggests that TTG+ may participate in auditory-motor integration. TTG+ likely participates in facial expressions in response to emotional cues during an auditory discourse. [ABSTRACT FROM AUTHOR]

• Primary hub was significantly closer to the stereotactic EEG-defined seizure onset zone compared to the center of ECD cluster. • Both ECD cluster and network analyses suggested that spatially restricted region correlate with better seizure outcomes. • Our findings suggest that magnetoencephalography network analysis could be a valuable complement to the conventional ECD method. To clinically validate the connectivity-based magnetoencephalography (MEG) analyses to identify seizure onset zone (SOZ) with comparing to equivalent current dipole (ECD). The ECD cluster was quantitatively analyzed by calculating the centroid of the cluster and maximum distance (the largest distance between all dipoles). The "primary hub" was determined by the highest eigencentrality. The distribution of nodes in the top 5% of eigenvector centrality values was quantified by generating the convex hull between each node. Thirty-one patients who underwent MEG, stereotactic-EEG, and focal surgery were included. The primary hub was significantly closer to the sEEG-defined SOZ compared to ECD (p = 0.009). The seizure freedom positive and negative predictive values of complete ECD cluster and primary hub resections did not significantly differ, although complete resection of the primary hub showed slightly better negative predictive value (ECD: 50.0% NPV, hub: 64.7% NPV). Both quantitative ECD and functional connectivity analyses suggested that spatially restricted dipole distributions and higher connectivity in a smaller region correlate with better seizure outcomes. Our findings suggest that MEG network analysis could be a valuable complement to the ECD methods. The results of this study are an important step towards using non-invasive neurophysiologic recordings to accurately define the epileptic network. [ABSTRACT FROM AUTHOR]

Objective We evaluated the impact of radiotracer injection latency and post-injection seizure duration on subtraction ictal SPECT co-registered to MRI (SISCOM) test performance in identifying the epileptogenic zone (EZ) in children with drug-resistant epilepsy who had undergone a resective epilepsy surgery. Methods SISCOM concordance with the EZ was retrospectively reviewed to evaluate its performance in 113 children. The impact of radiotracer injection latency and post-injection seizure duration was evaluated for their predictive value of SISCOM localization accuracy. Results The overall sensitivity and specificity of SISCOM in identifying an EZ was 64.8% (95%CI = 50.6–77.3) and 40.7% (95%CI = 28.1–54.3). The positive likelihood ratio and diagnostic odd ratio was 1.09 (95%CI = 0.80–1.48) and 1.26 (95%CI = 0.59–2.71), respectively. Logistic regression showed that injection latency and post-injection seizure duration did not significantly predict the probability of true positive SISCOM (p-value = 0.45 and 0.29, respectively). Conclusion Radiotracer injection latency and post-injection seizure duration were not shown to have a statistical significant impact on SISCOM performance in identifying the EZ. Significance This study demonstrates that further study of factors contributing to the performance of SISCOM in EZ identification in children is needed. [ABSTRACT FROM AUTHOR]

Objectives This meta-analysis was performed to determine if acute postoperative seizures (APOS) predict epilepsy surgery outcomes. Additionally, we estimated pooled prevalence for APOS and explored if certain APOS characteristics predict surgical outcomes. Methods A systematic literature search was performed for studies reporting seizure outcomes after epilepsy surgery in patients with and without APOS. APOS were defined as seizure(s) occurring within 30 days of surgery. After data extraction, pooled Mantel-Haenszel odds ratio (OR) with 95% confidence intervals (CI) was calculated for 1-year seizure-free outcome in patients with and without APOS using random-effects meta-analysis. Sub-group meta-analysis for pediatric studies, time of occurrence, and APOS semiology were also performed. A meta-regression was performed to explore source(s) of heterogeneity. Results Seventeen studies were included in the final synthesis. Pooled prevalence of APOS was found to be 22.58%. A significantly higher proportion of patients without APOS within 30 days of surgery (73.49%) were seizure-free at ≥1-year (OR 4.20, 95% CI 2.97–5.93, p < 0.0001) compared to those with APOS (38.96%). Among the pediatric studies (n = 6) 77.14% of patients without APOS were seizure-free at ≥1-year, compared to 35.94% of those with APOS (OR 5.71, 95% CI 3.32–9.80, p < 0.0001). Patients having APOS within 24 h of surgery and APOS semiology different from habitual pre-surgical seizures were more likely to achieve seizure-free outcomes, but these results failed to achieve statistical significance. Conclusions APOS reliably predict 1-year seizure outcomes after epilepsy surgery. This information should help counsel patients and families. [ABSTRACT FROM AUTHOR]