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Highlights • Resection of HGM language sites is associated with worse neuropsychological outcomes. • Working memory was significantly worse in patients with resection of HGM naming sites. • Neuropsychological evaluation of children with epilepsy should include multiple cognitive and language domains. Abstract Background Language mapping with high-gamma modulation (HGM) has compared well with electrical cortical stimulation mapping (ESM). However, there is limited prospective data about its functional validity. We compared changes in neuropsychological evaluation (NPE) performed before and 1-year after epilepsy surgery, between patients with/without resection of cortical sites showing HGM during a visual naming task. Methods Pediatric drug-resistant epilepsy (DRE) patients underwent pre-surgical language localization with ESM and HGM using a visual naming task. Surgical decisions were based solely on ESM results. NPE difference scores were compared between patients with/without resection of HGM naming sites using principal component (PC) analysis. Follow-up NPE scores were modeled with resection group as main effect and respective pre-surgical score as a covariate, using analysis of covariance. Results Seventeen native English speakers (12 females), aged 6.5–20.2 years, were included. One year after epilepsy surgery, first PC score increased by (mean ± standard deviation) 14.4 ± 16.5 points in patients without resection, whereas it decreased by 7.6 ± 24.6 points in those with resection of HGM naming sites (p = 0.040). This PC score represented verbal comprehension, working memory, perceptual reasoning (Wechsler subscales); Woodcock-Johnson Tests of Achievement; and Peabody Picture Vocabulary Test. Subsequent analysis showed significant difference in working memory score between patients with/without resection of HGM naming sites (−15.2 points, 95% confidence limits −29.7 to −0.7, p = 0.041). Conclusion We highlight the functional consequences of resecting HGM language sites, and suggest that NPE of DRE patients should include comprehensive assessment of multiple linguistic and cognitive domains besides naming ability. [ABSTRACT FROM AUTHOR]

Purpose We studied the effect of fosphenytoin (FOS) pre-medication on the incidence and thresholds of after-discharges (ADs), seizures, and functional responses during electrical stimulation mapping (ESM). Methods As individualized by the attending epileptologist, FOS was given intravenously at 2 mg-phenytoin-equivalents (PE)/kg/min or 150 mg-PE/min (whichever slower). Patients who received and did not receive FOS were compared for the incidence and thresholds of ADs, seizures, and functional responses. Results Before ESM, 40 and 82 patients respectively were pre-medicated/not pre-medicated with FOS. The incidence of ESM-induced seizures was significantly lower in FOS pre-medicated patients (22.5% vs. 42.7%, p = 0.044), whereas temporal language threshold was higher (9.2 vs. 6.5 mA, p = 0.032). FOS was more efficacious in preventing ESM-induced seizures in patients with symptomatogenic zone ipsilateral to the side of ESM. Although FOS dose had no significant effect on minimum language, minimum motor, or AD thresholds; seizure and temporal language thresholds showed trends approaching significance, intersecting at 12.2 mg-PE/kg. The incidence of ESM-induced seizures was significantly lower in those who received FOS at a dose of ≤12 mg/kg (9.1%) compared to those who did not receive any FOS (42.7%, p = 0.046), while the temporal language thresholds were not significantly different (6.3 vs. 6.5 mA, p = 0.897). Conclusions This study provides class III evidence that FOS pre-medication before ESM decreases the incidence of ESM-induced seizures, but increases temporal language threshold. FOS pre-medication may thus be considered before ESM. Future studies should prospectively verify these observations and characterize dose-response relationships. [ABSTRACT FROM AUTHOR]

Objectives To determine the prevalence of epilepsy and drug-resistant epilepsy in pediatric patients with focal cortical dysplasia (FCD) identified by magnetic resonance imaging (MRI). To determine clinical and imaging differences between those with drug-resistant epilepsy, drug-responsive epilepsy, and no epilepsy among children with MRI-identified FCD. Methods A keyword search of a hospital radiology database identified 97 study participants for inclusion in this retrospective study. Participants were included if they were under 18 years of age at time of database query and had an MRI between 2004 and 2013 showing FCD. Exclusion was based on imaging and clinical characteristics. Data was gathered using a chart review and supplemental questionnaire. Results In this cohort of patients with imaging findings compatible with FCD, 29% had not developed epilepsy. The prevalence of epilepsy and drug-resistant epilepsy was 71.13% (95% C.I. = 61.05–79.89%) and 32.99% (95% C.I. = 23.78–43.27%), respectively. Patients with epilepsy were more likely to have temporal ( p = 0.029) or frontal ( p = 0.044) lobe lesions and a family history of seizures ( p = 0.003) than those without epilepsy. Age of seizure onset was later in those with drug-responsive epilepsy than those with drug-resistant epilepsy ( p = 0.0002). A later age of seizure onset (OR = 1.22, p = 0.0441, 95% C.I. = 1.00–1.486) and absence of developmental delay (OR = 3.624, p = 0.0497, 95% C.I. = 1.002–13.110) predicted a less severe epilepsy phenotype. Conclusions Previous studies have only assessed patient cohorts with FCD and epilepsy, limiting the data on “asymptomatic” or “atypically presenting” FCD. Identifying a surprisingly large, novel cohort of children with FCD that had not developed epilepsy helps define prognosis and inform clinical management of children with FCD on imaging. [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]

Purpose There is wide variation in clinical practice regarding the role of electrocorticography immediately after resection (post-resection ECoG) for pediatric epilepsy surgery. Results can guide further resection of potentially epileptogenic tissue. We hypothesized that post-resection ECoG spiking represents a biomarker of the epileptogenic zone and predicts seizure outcome in children undergoing epilepsy surgery. Methods We retrospectively identified 124 children with post-resection ECoG performed on the margins of resection. ECoG records were scored in a blinded fashion based on presence of frequent spiking. For patients identified as having additional resection based on clinical post-resection ECoG interpretation, these “second-look” ECoG results were re-reviewed for ongoing discharges or completeness of resection. Frequent spike populations were grouped using a standard scoring system into three ranges: 0.1–0.5 Hz, 0.5–1 Hz, >1 Hz. Seizure outcomes were determined at minimum 12-month followup. Results Of 124 patients who met inclusion criteria, 60 (48%) had an identified spike population on post-resection ECoG. Thirty (50%) of these had further resection based on clinical interpretation. Overall, good outcome (ILAE 1) was seen in 56/124 (45%). Completeness of resection of spiking (absence of spiking on initial post-resection ECoG or resolution of spiking after further resection) showed a trend toward good outcome (OR 2.03, p = 0.099). Patients with completeness of resection had good outcome in 41/80 (51%) of cases; patients with continued spikes had good outcome in 15/44 (35%) of cases. Conclusions Post-resection ECoG identifies residual epileptogenic tissue in a significant number of children. Lower frequency or absence of discharges on initial recording showed a trend toward good outcome. Completeness of resection demonstrated on final ECoG recording did not show a significant difference in outcome. This suggests that post-resection discharges represent a prognostic marker rather than a remediable biomarker of the epileptogenic zone in all patients. Resecting residual spike-generating cortex may be beneficial in selected patients, including children with tumors. [ABSTRACT FROM AUTHOR]

Summary Introduction This study describes development of a novel language mapping approach using high-γ modulation in electrocorticograph (ECoG) during spontaneous conversation, and its comparison with electrical cortical stimulation (ECS) in childhood-onset drug-resistant epilepsy. Methods Patients undergoing invasive pre-surgical monitoring and able to converse with the investigator were eligible. ECoG signals and synchronized audio were acquired during quiet baseline and during natural conversation between investigator and the patient. Using Signal Modeling for Real-time Identification and Event Detection (SIGFRIED) procedure, a statistical model for baseline high-γ (70–116 Hz) power, and a single score for each channel representing the probability that the power features in the experimental signal window belonged to the baseline model, were calculated. Electrodes with significant high-γ responses (HGS) were plotted on the 3D cortical model. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), and classification accuracy were calculated compared to ECS. Results Seven patients were included (4 males, mean age 10.28 ± 4.07 years). Significant high-γ responses were observed in classic language areas in the left hemisphere plus in some homologous right hemispheric areas. Compared with clinical standard ECS mapping, the sensitivity and specificity of HGS mapping was 88.89% and 63.64%, respectively, and PPV and NPV were 35.29% and 96.25%, with an overall accuracy of 68.24%. HGS mapping was able to correctly determine all ECS+ sites in 6 of 7 patients and all false—sites (ECS+, HGS− for visual naming, n = 3) were attributable to only 1 patient. Conclusions This study supports the feasibility of language mapping with ECoG HGS during spontaneous conversation, and its accuracy compared to traditional ECS. Given long-standing concerns about ecological validity of ECS mapping of cued language tasks, and difficulties encountered with its use in children, ECoG mapping of spontaneous language may provide a valid alternative for clinical use. [ABSTRACT FROM AUTHOR]