A multi-center comparison of surgical techniques for corpus Callosotomy in pediatric drug-resistant epilepsy.

OBJECTIVES: Corpus callosotomy (CC) is used to reduce seizures, primarily in patients with generalized drug-resistant epilepsy (DRE). The invasive nature of the procedure contributes to underutilization despite its potential superiority to other palliative procedures. The goal of this study was to use a multi-institutional epilepsy surgery database to characterize the use of CC across participating centers. METHODS: Data were acquired from the Pediatric Epilepsy Research Consortium (PERC) Surgery Database, a prospective observational study collecting data on children 0-18 years referred for surgical evaluation of DRE across 22 U.S. pediatric epilepsy centers. Patient, epilepsy, and surgical characteristics were collected across multiple CC modalities. Outcomes and complications were recorded and analyzed statistically. RESULTS: Eighty-three patients undergoing 85 CC procedures at 14 participating epilepsy centers met inclusion criteria. Mean age at seizure onset was 2.3 years (0-9.4); mean age for Phase I evaluation and surgical intervention were 9.45 (.1-20) and 10.46 (.2-20.6) years, respectively. Generalized seizure types were the most common (59%). Complete CC was performed in 88%. The majority of CC procedures (57%) were via open craniotomy, followed by laser interstitial thermal therapy (LiTT) (20%) and mini-craniotomy/endoscopic (mc/e) (22%). Mean operative times were significantly longer for LiTT, whereas mean estimated blood loss was greater in open cases. Complications occurred in 11 cases (13%) and differed significantly between surgical techniques (p < .001). There was no statistically significant difference in length of postoperative stay across approaches. Mean follow-up was 12.8 months (range 1-39). Favorable Engel outcomes were experienced by 37 (78.7%) of the patients who underwent craniotomy, 10 (58.8%) with LiTT, and 12 (63.2%) with mc/e; these differences were not statistically significant. SIGNIFICANCE: CC is an effective surgical modality for children with DRE. Regardless of surgical modality, complication rates are acceptable and seizure outcomes generally favorable. Newer, less-invasive, surgical approaches may lead to increased adoption of this efficacious therapeutic option for pediatric DRE.

Epilepsy center characteristics and geographic region influence presurgical testing in the United States.

OBJECTIVE: Persons with drug-resistant epilepsy may benefit from epilepsy surgery and should undergo presurgical testing to determine potential candidacy and appropriate intervention. Institutional expertise can influence use and availability of evaluations and epilepsy surgery candidacy. This census survey study aims to examine the influence of geographic region and other center characteristics on presurgical testing for medically intractable epilepsy. METHODS: We analyzed annual report and supplemental survey data reported in 2020 from 206 adult epilepsy center directors and 136 pediatric epilepsy center directors in the United States. Test utilization data were compiled with annual center volumes, available resources, and US Census regional data. We used Wilcoxon rank-sum, Kruskal-Wallis, and chi-squared tests for univariate analysis of procedure utilization. Multivariable modeling was also performed to assign odds ratios (ORs) of significant variables. RESULTS: The response rate was 100% with individual element missingness < 11% across 342 observations undergoing univariate analysis. A total of 278 complete observations were included in the multivariable models, and significant regional differences were present. For instance, compared to centers in the South, those in the Midwest used neuropsychological testing (OR = 2.87, 95% confidence interval [CI] = 1.2-6.86; p = .018) and fluorodeoxyglucose-positron emission tomography (OR = 2.74, 95% CI = = 1.14-6.61; p = .025) more commonly. For centers in the Northeast (OR = .46, 95% CI = .23-.93; p = .031) and West (OR = .41, 95% CI = .19-.87; p = .022), odds of performing single-photon emission computerized tomography were lower by nearly 50% compared to those in the South. Center accreditation level, demographics, volume, and resources were also associated with varying individual testing rates. SIGNIFICANCE: Presurgical testing for drug-resistant epilepsy is influenced by US geographic region and other center characteristics. These findings have potential implications for comparing outcomes between US epilepsy centers and may inject disparities in access to surgical treatment.

Associations between testing and treatment pathways in lesional temporal or extratemporal epilepsy: A census survey of NAEC center directors.

OBJECTIVE: The evaluation to determine candidacy and treatment for epilepsy surgery in persons with drug-resistant epilepsy (DRE) is not uniform. Many non-invasive and invasive tests are available to ascertain an appropriate treatment strategy. This study examines expert response to clinical vignettes of magnetic resonance imaging (MRI)-positive lesional focal cortical dysplasia in both temporal and extratemporal epilepsy to identify associations in evaluations and treatment choice. METHODS: We analyzed annual report data and a supplemental epilepsy practice survey reported in 2020 from 206 adult and 136 pediatric epilepsy center directors in the United States. Non-invasive and invasive testing and surgical treatment strategies were compiled for the two scenarios. We used chi-square tests to compare testing utilization between the two scenarios. Multivariable logistic regression modeling was performed to assess associations between variables. RESULTS: The supplemental survey response rate was 100% with 342 responses included in the analyses. Differing testing and treatment approaches were noted between the temporal and extratemporal scenarios such as chronic invasive monitoring selected in 60% of the temporal scenario versus 93% of the extratemporal scenario. Open resection was the most common treatment choice; however, overall treatment choices varied significantly (p < .001). Associations between non-invasive testing, invasive testing, and treatment choices were present in both scenarios. For example, in the temporal scenario stereo-electroencephalography (SEEG) was more commonly associated with fluorodeoxyglucose-positron emission tomography (FDG-PET) (odds ratio [OR] 1.85; 95% confidence interval [CI] 1.06-3.29; p = .033), magnetoencephalography (MEG) (OR 2.90; 95% CI 1.60-5.28; p = <.001), high density (HD) EEG (OR 2.80; 95% CI 1.27-6.24; p = .011), functional MRI (fMRI) (OR 2.17; 95% CI 1.19-4.10; p = .014), and Wada (OR 2.16; 95% CI 1.28-3.66; p = .004). In the extratemporal scenario, choosing SEEG was associated with increased odds of neuromodulation over open resection (OR 3.13; 95% CI 1.24-7.89; p = .016). SIGNIFICANCE: In clinical vignettes of temporal and extratemporal lesional DRE, epilepsy center directors displayed varying patterns of non-invasive testing, invasive testing, and treatment choices. Differences in practice underscore the need for comparative trials for the surgical management of DRE.

Drug-resistant temporal lobe epilepsy with temporal encephaloceles: How far to resect.

PURPOSE: This study sought to evaluate the impact of surgical extent on seizure outcome in drug-resistant temporal lobe epilepsy (DR-TLE) with temporal encephaloceles (TE). METHODS: This was a single-institution retrospective study of patients who underwent surgery for DR-TLE with TE between January 2008 and December 2020. The impact of surgical extent on seizure outcome was evaluated. In a subset with dominant DR-TLE, the impact of surgical extent on neuropsychometric outcome was evaluated. RESULTS: Thirty-four patients were identified (female, 56%; median age at surgery, 43 years). TE were frequently overlooked on initial magnetic resonance imaging (MRI), with encephaloceles only detected after repeat or expert re-review of MRI, additional multi-modal imaging, or intra-operatively in 31 (91%). Sixteen (47%) underwent limited resections, including encephalocele resection only (n = 5) and encephalocele resection with more extensive temporal corticectomy sparing the amygdala and hippocampus (n = 11). The remainder (n = 18, 53%) underwent standard anterior temporal lobectomy and amygdalohippocampectomy (ATLAH). Limited resection was performed more frequently on the left (12/17 vs. 4/17, p = 0.015). Twenty-seven patients (79%) had a favourable outcome (Engel I/II), and 17 (50%) were seizure-free at the last follow-up (median seizure-free survival of 27.3 months). There was no statistically significant difference in seizure-free outcomes between limited resection and ATLAH. In dominant DR-TLE, verbal memory decline was more likely after ATLAH than limited resection (3/4 vs. 0/9, p = 0.014). CONCLUSION: Expert re-review of imaging and multi-modal advanced imaging improved TE identification. There was no statistical difference in seizure-free outcomes based on surgical extent. Preservation of verbal memory supports limited resection in dominant temporal cases.

Neurostimulation in people with drug-resistant epilepsy: Systematic review and meta-analysis from the ILAE Surgical Therapies Commission.

OBJECTIVE: Summarize the current evidence on efficacy and tolerability of vagus nerve stimulation (VNS), responsive neurostimulation (RNS), and deep brain stimulation (DBS) through a systematic review and meta-analysis. METHODS: We followed the Preferred Reporting Items of Systematic reviews and Meta-Analyses reporting standards and searched Ovid Medline, Ovid Embase, and the Cochrane Central Register of Controlled Trials. We included published randomized controlled trials (RCTs) and their corresponding open-label extension studies, as well as prospective case series, with ≥20 participants (excluding studies limited to children). Our primary outcome was the mean (or median, when unavailable) percentage decrease in frequency, as compared to baseline, of all epileptic seizures at last follow-up. Secondary outcomes included the proportion of treatment responders and proportion with seizure freedom. RESULTS: We identified 30 eligible studies, six of which were RCTs. At long-term follow-up (mean 1.3 years), five observational studies for VNS reported a pooled mean percentage decrease in seizure frequency of 34.7% (95% confidence interval [CI]: -5.1, 74.5). In the open-label extension studies for RNS, the median seizure reduction was 53%, 66%, and 75% at 2, 5, and 9 years of follow-up, respectively. For DBS, the median reduction was 56%, 65%, and 75% at 2, 5, and 7 years, respectively. The proportion of individuals with seizure freedom at last follow-up increased significantly over time for DBS and RNS, whereas a positive trend was observed for VNS. Quality of life was improved in all modalities. The most common complications included hoarseness, and cough and throat pain for VNS and implant site pain, headache, and dysesthesia for DBS and RNS. SIGNIFICANCE: Neurostimulation modalities are an effective treatment option for drug-resistant epilepsy, with improving outcomes over time and few major complications. Seizure-reduction rates among the three therapies were similar during the initial blinded phase. Recent long-term follow-up studies are encouraging for RNS and DBS but are lacking for VNS.

Acetazolamide for electrical status epilepticus in slow-wave sleep.

Electrical status epilepticus in slow-wave sleep (ESES) is characterized by nearly continuous spike-wave discharges during non-rapid eye movement (REM) sleep. ESES is present in Landau-Kleffner syndrome (LKS) and continuous spike and wave in slow-wave sleep (CSWS). Sulthiame has demonstrated reduction in spike-wave index (SWI) in ESES, but is not available in the United States. Acetazolamide (AZM) is readily available and has similar pharmacologic properties. Our aims were to assess the effect of AZM on SWI and clinical response in children with LKS and CSWS. Children with LKS or CSWS treated with AZM at our institution were identified retrospectively. Pre- and posttherapy electroencephalography (EEG) studies were evaluated for SWI. Parental and teacher report of clinical improvement was recorded. Six children met criteria for inclusion. Three children (50%) demonstrated complete resolution or SWI <5% after AZM. All children had improvement in clinical seizures and subjective improvement in communication skills and school performance. Five of six children had subjective improvement in hyperactivity and attention. AZM is a potentially effective therapy for children with LKS and CSWS. This study lends to the knowledge of potential therapies that can be used for these disorders, which can be challenging for families and providers.

CNS imaging findings associated with Parry-Romberg syndrome and en coup de sabre: correlation to dermatologic and neurologic abnormalities.

INTRODUCTION: Parry-Romberg syndrome (PRS) and en coup de sabre (ECS) are variants of morphea. Although numerous findings on central nervous system (CNS) imaging of PRS and ECS have been reported, the spectrum and frequency of CNS imaging findings and relation to cutaneous and neurologic abnormalities have not been fully characterized. METHODS: We retrospectively reviewed patients younger than 50 years at our institution over a 16-year interval who had clinical diagnosis of PRS and ECS by a skin or facial subspecialist. Two neuroradiologists evaluated available imaging and characterized CNS imaging findings. RESULTS: Eighty-eight patients with PRS or ECS were identified (62 women [70.4 %]; mean age 28.8 years). Of the 43 patients with CNS imaging, 19 (44 %) had abnormal findings. The only finding in 1 of these 19 patients was lateral ventricle asymmetry; of the other 18, findings were bilateral in 11 (61 %), ipsilateral to the side of facial involvement in 6 (33 %), and contralateral in 1 (6 %). Sixteen patients had serial imaging examinations over an average of 632 days; 13 (81 %) had stable imaging findings, and 3 (19 %) had change over time. Of six patients with progressive cutaneous findings, five (83 %) had stable imaging findings over time. Among the 23 patients with clinical neurologic abnormality and imaging, 12 (52 %) had abnormal imaging findings. All seven patients with seizures (100 %) had abnormal imaging studies. CONCLUSIONS: In PRS and ECS, imaging findings often are bilateral and often do not progress, regardless of cutaneous disease activity. Findings are inconsistently associated with clinical abnormalities.

Seizure outcome after AED failure in pediatric focal epilepsy: impact of underlying etiology.

OBJECTIVE: This study aimed to identify long-term seizure outcome in pediatric nonsyndromic focal epilepsy after failure of serial antiepileptic drugs (AEDs) due to lack of efficacy. METHODS: Children (1 month-17 years) with new-onset focal epilepsy not meeting the criteria for a defined electroclinical syndrome diagnosed between 1980 and 2009 while residing in Olmsted County, MN, were retrospectively identified. Medical records of those followed for ≥2 years were reviewed to assess etiology, the number of AEDs that failed due to lack of efficacy, and seizure outcome at final follow-up. Etiology was classified into structural/metabolic, genetic, or unknown. Favorable outcome was defined as seizure freedom ≥1 year, on or off AEDs, without prior epilepsy surgery. Poor outcome was defined as ongoing seizures in the preceding year or having undergone prior epilepsy surgery. RESULTS: Nonsyndromic focal epilepsy accounted for 275/468 (59%) of all patients with newly diagnosed epilepsy--of these, 256 (93%) were followed for a minimum of two years and were included in the study. Median duration of follow-up was 10.0 years. At least one AED had failed due to lack of efficacy in 100 (39.1%) children. Favorable outcomes occurred in 149/156 (95.5%) children with no AED failure, 16/30 (53.3%) with one AED failure, 8/25 (32%) with two AED failures, and only 2/45 (4.4%) with three AED failures. After two AED failures, the seizures of nearly one-quarter of children who had epilepsy with an unknown cause responded favorably to the third AED compared with only 7.8% of the cohort that had epilepsy with a structural/metabolic cause. Children with a remote brain insult had a significantly higher likelihood of favorable outcome with serial AEDs than those with other structural abnormalities. SIGNIFICANCE: Etiology is an important determinant of pharmacoresistance in nonsyndromic focal epilepsy. Surgical evaluation should be considered after failure of 1-2 AEDs in those who have epilepsy with structural causes, excluding remote brain insults. Conversely, as surgical success is lower with normal MRI or more diffuse brain insults, it appears reasonable to hold off surgical evaluation until 2-3 AEDs have failed in such children.

What predicts enduring intractability in children who appear medically intractable in the first 2 years after diagnosis?

PURPOSE: In a population-based retrospective cohort of children with newly diagnosed epilepsy, to determine (1) what proportion meet criteria for early medical intractability, and (2) predictors of enduring intractability. METHODS: Children with newly diagnosed epilepsy between 1980 and 2009 while resident in Olmsted County, MN, and followed >36 months, were stratified into groups based on both early medical intractability ("apparent" medical intractability in the first 2 years) and enduring intractability (persisting intractability at final follow-up or having undergone surgery for intractable epilepsy), and variables predicting these outcomes were evaluated. KEY FINDINGS: Three hundred eighty-one children were included, representing 81% of our cohort with newly diagnosed epilepsy. Seventy five (19.7%) had early medical intractability, and predictors of this outcome on multivariable analysis were neuroimaging abnormality (risk ratio, 2.70; p = 0.0004), abnormal neurologic examination at diagnosis (risk ratio, 1.87; p = 0.015), and mode of onset (association was significant for focal vs. generalized onset [risk ratio, 0.25; p < 0.0001] but not unknown vs. generalized onset [p = 0.065]). After a median follow-up of 11.7 years, 49% remained intractable, 8% had rare seizures (≤ every 6 months), and the remainder were seizure-free. The only factor predicting enduring intractability on multivariable analysis was neuroimaging abnormality (risk ratio, 7.0; p = 0.0006). SIGNIFICANCE: Although a significant minority of children with early medical intractability ultimately achieved seizure control without surgery, those with an abnormal imaging study did poorly. For this subgroup, early surgical intervention is strongly advised to limit comorbidities of ongoing, intractable seizures. Conversely, a cautious approach is suggested for those with normal imaging, as most will remit with time.

Stereo-EEG localization of midline onset seizures on scalp EEG.

PURPOSE: The objective of this study was to describe the sEEG-defined seizure onset zone (SOZ), seizure semiology, presurgical evaluations, surgical intervention and outcome in patients with midline onset noninvasive phase I monitoring. METHODS: A single center sEEG database was reviewed to identify patients with seizures onset predominantly involving midline electrodes (FZ, CZ, PZ, OZ) on scalp EEG. Data abstracted included clinical factors, seizure semiology graded into lobar segmentation, imaging and electrographic findings, sEEG plan, interventions, and outcome. RESULTS: Twelve patients were identified (8 males, median age of sEEG 28 years) out of 100 cases of sEEG performed from January 2015-September 2019. "Frontal lobe" seizure semiology was the most common. sEEG-defined SOZ were frontal (5), diffuse (1), multifocal (1), frontal and insular (1), frontal and cingulate (1), insular (1), cingulate (1), and mesial temporal (1). CZ and/or FZ scalp EEG changes were present for all patients with SOZ involving the frontal, cingulate, and insular regions. PZ/OZ scalp involvement was present in one patient with mesial temporal SOZ. Four patients underwent a definitive resective or ablative surgery, and the remaining patients underwent a palliative intervention. Of those with follow-up information available, 8/11 had seizure reduction by ≥ 50%, including 4 with an Engel I outcome. No clinical factors were associated with outcome. CONCLUSIONS: SOZ for midline onset seizures from noninvasive phase I monitoring was most commonly in the frontal, cingulate, and insular regions. A complex cortical network between these regions may explain overlap in semiology and scalp EEG findings. While the number rendered seizure-free was limited, a significant proportion experienced a reasonably favorable outcome justifying use of sEEG to identify surgical options in these patients.

EEG Source Localization in Temporal Encephaloceles: Concordance With Surgical Resection and Clinical Outcomes.

PURPOSE: Temporal encephaloceles are a cause of drug-resistant temporal lobe epilepsy; however, their relationship with epileptogenesis is unclear, and optimal surgical resection is uncertain. EEG source localization (ESL) may guide surgical decision-making. METHODS: We reviewed patients at Mayo Clinic Rochester with drug-resistant temporal lobe epilepsy and temporal encephaloceles, who underwent limited resection and had 1-year outcomes. EEG source localization was performed using standard density scalp EEG of ictal and interictal activity. Distance from dipole and standardized low-resolution brain electromagnetic tomography (sLORETA) solutions to the encephalocele were measured. Concordance of ESL with encephalocele and surgical resection was compared with 1-year surgical outcomes. RESULTS: Seventeen patients met criteria. The mean distances from ESL results to encephalocele center for dipole and sLORETA analyses were 23 mm (SD 9) and 22 mm (SD 11), respectively. Ten patients (55.6%) had Engel I outcomes at 1 year. Dipole-encephalocele distance and sLORETA-encephalocele distance were significantly longer in patients with Engel I outcome and patients whose encephalocele was contained by sLORETA had worse outcome as well; however, multiple logistic regression analysis found that only containment of encephalocele by the sLORETA current density was significant (P < 0.05), odds ratio 0.12 (95% confidence interval [0.021, 0.71]). CONCLUSIONS: EEG source localization of scalp EEG localizes near encephaloceles, however, typically not in the encephalocele itself; this may be due to scalp EEG sampling propagated activity or alternatively that the seizure onset zone extends beyond the herniated cortex. Surprisingly, we observed increased ESL to encephalocele distances in patients with excellent surgical outcomes. Larger cohort studies including intracranial EEG data are needed to further explore this finding.

Association Between Characteristics of National Association of Epilepsy Centers and Reported Utilization of Specific Surgical Techniques.

BACKGROUND AND OBJECTIVE: Nearly one-third of persons with epilepsy will continue having seizures despite trialing multiple antiseizure medications. Epilepsy surgery may be beneficial in these cases, and evaluation at a comprehensive epilepsy center is recommended. Numerous palliative and potentially curative approaches exist, and types of surgery performed may be influenced by center characteristics. This article describes epilepsy center characteristics associated with epilepsy surgery access and volumes in the United States. METHODS: We analyzed National Association of Epilepsy Centers 2019 annual report and supplemental survey data obtained with responses from 206 adult epilepsy center directors and 136 pediatric epilepsy center directors in the United States. Surgical treatment volumes were compiled with center characteristics, including US Census region. We used multivariable modeling with zero-inflated Poisson regression models to present ORs and incidence rate ratios of receiving a given surgery type based on center characteristics. RESULTS: The response rate was 100% with individual element missingness less than 4% across 352 observations undergoing univariate analysis. Multivariable models included 319 complete observations. Significant regional differences were present. The rates of laser interstitial thermal therapy (LITT) were lower at centers in the Midwest (incidence rate ratio [IRR] 0.74, 95% CI 0.59-0.92; p = 0.006) and Northeast (IRR 0.77, 95% CI 0.61-0.96; p = 0.022) compared with those in the South. Conversely, responsive neurostimulation implantation rates were higher in the Midwest (IRR 1.45, 95% CI 1.1-1.91; p = 0.008) and West (IRR 1.91, 95% CI 1.49-2.44; p < 0.001) compared with the South. Center accreditation level, institution type, demographics, and resources were also associated with variations in access and rates of potentially curative and palliative surgical interventions. DISCUSSION: Epilepsy surgery procedure volumes are influenced by US epilepsy center region and other characteristics. These variations may affect access to specific surgical treatments for persons with drug resistant epilepsy across the United States.

Epilepsy surgery in children with genetic etiologies: A prospective evaluation of current practices and outcomes.

OBJECTIVE: This study assesses current practices and outcomes of epilepsy surgery in children with a genetic etiology. It explores the pre-surgical workup, types of surgeries, and post-surgical outcomes in a broad array of disorders. METHODS: Patients ≤18 years who completed epilepsy surgery and had a known genetic etiology prior to surgical intervention were extrapolated from the Pediatric Epilepsy Research Consortium (PERC) surgery database, across 18 US centers. Data were assessed univariably by neuroimaging and EEG results, genetic group (structural gene, other gene, chromosomal), and curative intent. Outcomes were based on a modified International League Against Epilepsy (ILAE) outcome score. RESULTS: Of 81 children with genetic epilepsy, 72 % had daily seizures when referred for surgery evaluation, which occurred a median of 2.2 years (IQR 0.3, 5.2) after developing drug resistance. Following surgery, 68 % of subjects had >50 % seizure reduction, with 33 % achieving seizure freedom [median follow-up 11 months (IQR 6, 17). Seizure freedom was most common in the monogenic structural group, but significant palliation was present across all groups. Presence of a single EEG focus was associated with a greater likelihood of seizure freedom (p=0.02). SIGNIFICANCE: There are meaningful seizure reductions following epilepsy surgery in the majority of children with a genetic etiology, even in the absence of a single structural lesion and across a broad spectrum of genetic causes. These findings highlight the need for expedited referral for epilepsy surgery and support of a broadened view of which children may benefit from epilepsy surgery, even when the intent is palliative.

Autoimmune encephalopathies and epilepsies in children and teenagers.

Recognition of autoimmune encephalopathies and epilepsies in children and teenagers with acute or subacute onset of central nervous system dysfunction, through detection of the pertinent antibody on serum or cerebral spinal fluid, or through a response to immunotherapy may lead to an early diagnosis, and thus expedited implementation of immunotherapy and improved neurological outcome. The epidemiology of pediatric autoimmune encephalopathy and epilepsy is not well established, but advances in disease-specific biomarker discovery have lead to identification of disorders with either a cytotoxic T cell mediated pathogenesis or (more recently) possible autoantibody mediated disorders. This review summarizes the clinical presentations and recommended evaluations and treatment of pediatric epileptic encephalopathy suspected to be of autoimmune etiology.

Masking for School-Age Children With Epilepsy: We Do Have Consensus!

INTRODUCTION: This study was designed to assess current recommendations from child neurologists and epileptologists on masking for school-age children with epilepsy. METHODS: A 7-item survey was created and sent out to members of the Child Neurology Society and Pediatric Epilepsy Research Consortium in August of 2021 to assess current practice and provider recommendations on masking. RESULTS: One hundred four individuals participated with representation from all regions of the United States. Masking was recommended by 95.1%, with 63.4% (n = 66) noting exception of those with severe intellectual disability, autism, and behavioral problems. Of those who write exemption letters, 54% write these <5% of the time. Only 3% reported potential adverse events associated with masking. CONCLUSION: Nearly all respondents recommended masking for school-age children with epilepsy. Potential risks of masking and adverse events were low. Improved guidance on masking is needed to ensure academic success of our patients with epilepsy.

Association of intracranial abnormalities with the development of epilepsy and drug-resistant epilepsy in patients with Parry-Romberg syndrome.

BACKGROUND: Epilepsy represents an essential component of Parry Romberg syndrome (PRS). This study aimed to identify clinical factors that influence the development of epilepsy and drug-resistant epilepsy (DRE) in PRS. METHODS: We retrospectively reviewed the medical records of eighty patients with PRS. Data including the age of onset for PRS, history of seizures, use and timing of immunotherapy, antiseizure medication use, and EEG and brain imaging findings were reviewed. For comparison with the patients with epilepsy (PRSe+) group, we selected 18 age and sex-matched controls from the patient without epilepsy (PRSe-) cohort using propensity score matching. RESULTS: Eighteen (22.5%) had epilepsy: 12 were female, and the median age was 14.5 years (range = 6-48 years). Eleven patients developed DRE. The median latency between the onset of cutaneous manifestations and diagnosis and timing and use of immunotherapy was similar between the PRSe + and PRSe- groups. Intracranial abnormalities were commonly seen in the PRSe + group (16 vs. 2, p < 0.01). White matter disease and ipsilateral atrophy were common among the PRSe + group. Timing and use of immunotherapy, epileptiform discharges, and brain imaging abnormalities did not differ between those with DRE and without. CONCLUSIONS: The presence and degree of severity of ipsilateral brain abnormalities are risk factors for the development of epilepsy in PRS but not factors in predicting drug resistance. The timing of immunotherapy did not influence the development of PRSe + or DRE. Prospective studies are needed to identify biomarkers for epilepsy and assess the role of immunotherapy on seizure outcomes in PRSe + .

Subclinical seizures on stereotactic EEG: characteristics and prognostic value.

OBJECTIVE: Although stereotactic EEG (sEEG) has become a widely used intracranial EEG technique, the significance of subclinical seizures (SCS) recorded on sEEG is unclear and studies examining this finding on sEEG are limited. We investigated (1) the prevalence of SCS in patients undergoing sEEG and clinical factors associated with their presence, (2) how often the subclinical seizure onset zone (SOZ) colocalizes with clinical SOZ, (3) the association of SCS and surgical outcomes, and (4) the influence of resection of the subclinical SOZ on surgical outcome. METHODS: We reviewed all patients who underwent intracranial monitoring with sEEG at our institution from 2015 through 2020 (n=169). Patient and seizure characteristics were recorded, as was concordance of subclinical and clinical seizures and post-surgical outcomes. RESULTS: SCS were observed during sEEG monitoring in 84 of 169 patients (50%). There was no difference in the prevalence of SCS based on imaging abnormalities, temporal vs extratemporal SOZ, number of electrodes, or pathology. SCS were more common in females than males (62% vs 40%, p=0.0054). SCS had complete concordance with clinical SOZ in 40% of patients, partial concordance in 29%, overlapping in 19%, and discordant in 12%. Eighty-three patients had surgery, 44 of whom had SCS. There was no difference in excellent outcome (ILAE 12 or 2) based on the presence of SCS or SCS concordance with clinical SOZ; however, there were improved outcomes in patients with complete resection of the subclinical SOZ compared with patients with incomplete resection (p =0.013). SIGNIFICANCE: These findings demonstrate that SCS are common during sEEG and colocalize with the clinical SOZ in most patients. Discordance with clinical SOZ does not necessarily predict poor surgical outcome; rather, complete surgical treatment of the subclinical SOZ correlates with excellent outcome. For unclear reasons, subclinical seizures occurred more commonly in females than males.

The utility of diffusion tractography for speech preservation in laser ablation of the dominant insula: illustrative case.

BACKGROUND: Open surgical treatment of insular epilepsy holds particular risk of injury to middle cerebral artery branches, the operculum (through retraction), and adjacent language-related white matter tracts in the language-dominant hemisphere. Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (LITT) is a surgical alternative that allows precise lesioning with potentially less operative risk. The authors presented the case of a 13-year-old girl with intractable, MRI-negative, left (dominant hemisphere) insular epilepsy that was treated with LITT. Diffusion tensor imaging (DTI) tractography was used to aid full posterior insular lesioning in the region of stereo electroencephalography-determined seizure onset while avoiding thermal injury to the language-related superior longitudinal fasciculus (SLF)/arcuate fasciculus (AF) and inferior fronto-occipital fasciculus (IFOF). OBSERVATIONS: DTI tractography was used successfully in planning insular LITT and facilitated a robust insular ablation with sharp margins at the interfaces with the SLF/AF and IFOF. These tracts were spared, and no neurological deficits were induced through LITT. LESSONS: Although it is technically demanding and has important limitations that must be understood, clinically available DTI tractography adds precision and confidence to insular laser ablation when used to protect important language-related white matter tracts.

EEG source imaging concordance with intracranial EEG and epileptologist review in focal epilepsy.

EEG source imaging is becoming widely used for the evaluation of medically refractory focal epilepsy. The validity of EEG source imaging has been established in several studies comparing source imaging to the surgical resection cavity and subsequent seizure freedom. We present a cohort of 87 patients and compare EEG source imaging of both ictal and interictal scalp EEG to the seizure onset zone on intracranial EEG. Concordance of EEG source imaging with intracranial EEG was determined on a sublobar level and was quantified by measuring the distance between the source imaging result and the centroid of the active seizure onset zone electrodes. The EEG source imaging results of a subgroup of 26 patients with high density 76-channel EEG were compared with the localization of three experienced epileptologists. Of 87 patients, 95% had at least one analysis concordant with intracranial EEG and 74% had complete concordance. There was a higher rate of complete concordance in temporal lobe epilepsy compared to extratemporal (89.3 and 62.8%, respectively, P = 0.015). Of the total 282 analyses performed on this cohort, higher concordance was also seen in temporal discharges (95%) compared to extratemporal (77%) (P = 0.0012), but no difference was seen comparing high-density EEG with standard (32-channel) EEG. Subgroup analysis of ictal waveforms showed greater concordance for ictal spiking, compared with rhythmic activity, paroxysmal fast activity, or obscured onset. Median distances from the dipole and maximum distributed source to a centroid of seizure onset zone electrodes were 30.0 and 32.5 mm, respectively, and the median distances from dipole and maximum distributed source to nearest seizure onset zone electrode were 22.8 and 21.7, respectively. There were significantly shorter distances in ictal spiking. There were shorter distances in patients with Engel Class 1 outcome from surgical resection compared to patients with worse outcomes. For the subgroup of 26 high-density EEG patients, EEG source localization had a significantly higher concordance (92% versus 65%), sensitivity (57% versus 35%) and positive predictive value (60% versus 36%) compared with epileptologist localization. Our study demonstrates good concordance between ictal and interictal source imaging and intracranial EEG. Temporal lobe discharges have higher concordance rates than extratemporal discharges. Importantly, this study shows that source imaging has greater agreement with intracranial EEG than visual review alone, supporting its role in surgical planning.

Iron Deficiency and Its Role in Sleep Disruption in Patients With Angelman Syndrome.

OBJECTIVE: To determine if Angelman syndrome patients with sleep complaints have an increased risk of iron deficiency, and if iron therapy improves their sleep difficulties. BACKGROUND: About two-thirds of Angelman syndrome patients experience sleep difficulties, which are likely multifactorial. Because iron deficiency can contribute toward restlessness in sleep, we investigated whether it might be a contributing factor in this special population. METHODS: This retrospective study involved medical record review of Angelman syndrome patients <18 years old who had attended our multidisciplinary Angelman syndrome clinic and had sleep complaints. Serum ferritin levels were compared to age- and sex-matched controls. Sleep history and nocturnal polysomnogram findings of the Angelman syndrome patients were also characterized. RESULTS: Nineteen Angelman syndrome patients (9 female, mean age 6.2±4.4 years) were identified. All 19 reported sleep difficulties. The mean serum ferritin level was 19.9±8.5 µg/L, while that in controls was 27.8±17.8 µg/L (P value .13). The odds ratio of iron deficiency in Angelman syndrome compared to controls was 4.17 (95% confidence interval 1.23-14.10), using normal serum ferritin level of 24 µg/L based on literature. Fifteen Angelman syndrome patients underwent nocturnal polysomnogram with 9/15 showing an elevated periodic limb movement index (overall mean 9.8±10.4). Seventeen of 19 received iron therapy. Twelve had follow-up after iron therapy, with parents reporting improved sleep quality. Eight had serum ferritin levels rechecked after iron therapy, showing a mean increase of 24±5.1 µg/L. CONCLUSIONS: Sleep difficulties in Angelman syndrome, though multifactorial, may in part be related to iron deficiency. Treatment with iron improved sleep to a modest degree in this population.