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Objective To evaluate the safety, tolerability, and pharmacokinetics of soticlestat, a first-in-class cholesterol 24-hydroxylase inhibitor, in adults with developmental and/or epileptic encephalopathies (DEE). Methods The study comprised a 30-day, randomized, double-blind, placebo-controlled phase (Part A), followed by a 55-day open-label phase (Part B) (ClinicalTrials.gov ID: NCT03166215) . In Part A, patients with DEE and at least one bilateral motor seizure during the 4-week prospective baseline period were randomized 4:1 to receive soticlestat or placebo, in addition to their usual antiseizure medication. In Part B, all patients received open-label soticlestat. Soticlestat doses were titrated according to tolerability to a maximum of 300 mg twice daily (BID). Safety evaluations included the incidence of treatment-emergent adverse events (TEAEs). Plasma soticlestat concentrations were measured at various times for determination of multiple-dose pharmacokinetics and 24S-hydroxycholesterol (24HC). Efficacy was assessed by evaluation of changes in seizure frequency from baseline. Results Eighteen patients (median age, 28.5 years) were enrolled and randomized, and 14 (78 %) completed the study. In Part A, TEAEs occurred in 71.4 % of soticlestat-treated patients and 100 % of placebo-treated patients. In Part B, the overall incidence of TEAEs was 68.8 %. In Part A, TEAEs that occurred in more than one patient in the soticlestat group were dysarthria (n = 3, 21.4 %), lethargy (n = 2, 14.3 %), upper respiratory tract infection (n = 2, 14.3 %), fatigue (n = 2, 14.3 %), and headache (n = 2, 14.3 %). Four patients discontinued treatment because of TEAEs, of whom two reported drug-related seizure clusters as serious TEAEs. There were no deaths. Pharmacokinetic analysis showed dose-dependent increases in systemic exposure and peak plasma soticlestat concentrations. At the end of Part B, the overall mean percent change from baseline in plasma 24HC was −80.97 %. Changes from baseline in median seizure frequency were +16.71 % and +22.16 % in the soticlestat and placebo groups, respectively, in Part A, and −36.38 % in all participants in Part B. Conclusion Soticlestat was well tolerated at doses of up to 300 mg BID and was associated with a reduction in median seizure frequency over the study duration. Further studies are warranted to assess the possible efficacy of soticlestat as adjunctive therapy in patients with DEEs such as Dravet syndrome and Lennox–Gastaut syndrome.

Introduction There is overlap in the electroclinical features of many childhood epilepsy syndromes, especially those presenting with multiple seizure types, such as epilepsy with myoclonic-atonic seizures (EMAS) and Lennox-Gastaut syndrome (LGS). This study aimed to determine the frequency of diagnosis switching and the factors influencing epilepsy syndrome diagnosis in a cohort of children with possible EMAS, as well as to explore the relationship between epilepsy syndrome diagnoses, key electroclinical features, and clinically relevant outcomes. Methods This is a cross-sectional retrospective chart review of children treated at the Children’s Hospital of Colorado with a potential diagnosis of EMAS. Results There were 77 patients that met eligibility criteria, including 39% (n = 30) with an initial diagnosis of EMAS and 74% (n = 57) with a final diagnosis of EMAS. On average, for the 65% of patients who received more than one epilepsy diagnosis, the first, second, and third diagnoses were received within one year, three years, and ten years after epilepsy onset, respectively. Final diagnosis was significantly related to obtaining at least a six-month period of seizure freedom, p = 0.03. Classic LGS traits, including paroxysmal fast activity, slow spike-and-wave, and tonic seizures were present in 50% of the overall cohort, although a minority of these patients had a final diagnosis of LGS. However, the presence of more LGS traits was associated with a higher likelihood of ongoing seizures. Adjusted for age of epilepsy onset, seizure freedom was half as likely for every additional LGS trait observed (0.49[0.31, 0.77], p = 0.002). Conclusion Current epilepsy syndrome classification has reduced applicability due to overlapping features. This results in diagnosis switching and limited prognostic value for patients with an overlapping clinical phenotype. Future studies should attempt to stratify patients based not only on epilepsy syndrome diagnosis, but also on the presence of various electroclinical traits to more accurately predict outcome.

Objective The aim of the current study was to investigate the long-term outcome in a large cohort of patients with Lennox-Gastaut syndrome (LGS). Methods This was a longitudinal study (a retrospective database review with a telephone follow-up interview). All patients 18 years of age and older, with a diagnosis of LGS were studied at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 until 2020. The inclusion criteria were: multiple seizure types, characteristic electroencephalographic patterns [either bursts of slow spike-waves or generalized paroxysmal fast activity], with or without intellectual disability. Being lost on follow-up was the only exclusion criterion. Results 78 patients fulfilled the inclusion criteria. All the patients were followed for one to 12 years (9.3 ± 2.8 years). In the last follow-up (call), 14 patients (17.9%) were seizure-free for at least 12 months. Tonic seizure at diagnosis was associated with a poor seizure outcome (not seizure-free) (p = 0.045). Four patients (5.1%) reported having high school degree (diploma), four patients (5.1%) were married, and one person (1.3%) reported driving a motor vehicle; none of the patients were employed. Conclusion A minority of patients with LGS (almost one in six patients) may enjoy a seizure-free state in their adulthood. However, very few of them could enjoy a healthy social life. While intellectual dysfunction may not be evident at the onset of the disease, cognitive impairment usually becomes apparent over time, and almost all patients would suffer from poor social outcomes in their adulthood.

Objective Patients diagnosed with Lennox Gastaut syndrome (LGS), an epileptic encephalopathy characterized by usually drug resistant generalized and focal seizures, are often considered as candidates for vagus nerve stimulation (VNS). Recent research shows that heart rate variability (HRV) differs in epilepsy patients and is related to VNS treatment response. This study investigated pre-ictal HRV in generalized onset seizures of patients with LGS in correlation with their VNS response. Methods In drug resistant epilepsy (DRE) patients diagnosed with LGS video-electroencephalography recording was performed during their pre-surgical evaluation. Six HRV parameters (time and-, frequency domain, non-linear parameters) were evaluated for every seizure in epochs of 10 min at baseline (60 to 50 min before seizure onset) and pre-ictally (10 min prior to seizure onset). The results were correlated to VNS response after one year of VNS therapy. Results Seven patients and 31 seizures were included, two patients were classified as VNS responders (≥ 50 % seizure reduction). No difference in pre-ictal HRV parameters between VNS responders and VNS non-responders could be found, but high frequency (HF) power, reflecting the parasympathetic tone increased significantly in the pre-ictal epoch in both VNS responders and VNS non-responders (p = 0.017, p = 0.004). Significance In this pilot data pre-ictal HRV did not differ in VNS responders compared to VNS non-responders, but showed a significant increase in HF power – a parasympathetic overdrive - in both VNS responders and VNS non-responders. This sudden autonomic imbalance might have an influence on the cardiovascular system in the ictal period. Generalized tonic-clonic seizures are regarded as the main risk factor for SUDEP and severe seizure-induced autonomic imbalance may play a role in the pathophysiological pathway.

Objective To assess long-term efficacy and tolerability of rufinamide in children with epilepsy and a broad spectrum of underlying epileptic etiologies. Methods Patients with epilepsy treated with rufinamide between 1/1/2009 and 1/1/2018 at Seattle Children’s Hospital were included. Data were collected via retrospective chart review. Rufinamide efficacy was defined as seizure reduction from baseline including seizure free, >50% reduction, any reduction, no reduction, or worsening seizures. Pearson’s chi-square test was used for statistical analysis. Results 183 patients (70 females and 113 males) with a broad spectrum of epileptic aetiologies (genetic/metabolic, hypoxic-ischemic, structural and others) were included. 45.9% of the patients had Lennox Gastaut syndrome. Rate of any seizure reduction was at 47.5%, seizure reduction >50% at 35%, and seizure free at 3.3%. Mean rufinamide dosage was 33.9 mg/kg/d (SD = 14.12). Mean duration of treatment was 44.48 months (SD 32.33). Suspected adverse effects occurred at 10.9%, most often as fatigue. Rufinamide achieved better seizure reduction in girls compared to boys [OR = 0.52, 95% CI (0.28, 0.97), p = 0.038]. Seizures were activated in a patient with a SCN1A mutation, fully controlled in a patient with a SCN8A mutation. Patients with certain genetic abnormalities such as DEPDC5, KCNQ2, SPATA5, and 47XYY achieved significant seizure reduction. Conclusions Rufinamide is an effective and well-tolerated drug for long-term treatment in pediatric patients with intractable epilepsy. Certain genotypes such as SCN8A showed good response to rufinamide. Girls seemed to respond better than boys.

To describe the use of a population pharmacokinetic (PopPK) model incorporating weight and ontogeny to identify effective clobazam (CLB) dosing for use in a clinical trial in pediatric patients with Dravet syndrome.Pharmacokinetic data were combined from 3 CLB trials (OV-1012, OV-1017, and study 301) and a simulated study (study 401) for a total of 1306 CLB and 1305 N-desmethyl clobazam (N-CLB) samples from 193 Lennox-Gastaut syndrome patients and healthy subjects aged 6 months to 45 years. A structured approach based on US Food and Drug Administration guidance and pharmacometric knowledge discovery was developed using a nonlinear mixed-effects approach. Graphing and fitting using logistical weight regression were used to identify covariates for inclusion in the final model, which was evaluated using goodness-of-fit criteria and validated using prediction-corrected visual predictive check (pcVPC). Using the final PopPK model, a simulation study determined CLB and N-CLB distributions after 4 weeks of 1.5 and 2.0 mg/kg CLB.The parameters of the final PopPK model were similar to previous reports. Fixed-effect parameters were precisely estimated, with no significant increase in NONMEM objective function value. Intersubject variability estimates were similar to previous reports, with35% shrinkage associated with parameter variability, except for intercompartmental clearance and apparent volumes of distribution of peripheral compartments. Goodness-of-fit plots and pcVPC show that the model adequately described CLB and N-CLB data. The CLB/N-CLB ratio in virtual study subjects aged3 years was 0.23 for 1.5 and 2.0 mg/kg and was 0.14 for subjects aged ≥3 years, which is 2 to 3 times those reported in a previous stiripentol/CLB/valproate study in which seizure improvement was reported.The PopPK model dosing parameters of 1.5 and 2.0 mg/kg are likely to result in efficacious concentrations of CLB and N-CLB in pediatric patients as young as 16 months. Dosages exceeding 1.5 mg/kg should be monitored for tolerability, particularly in patients aged2 years, as there may be a higher incidence of sedation.

Background Since 2014, patients with severe treatment-resistant epilepsies (TREs) have been receiving add-on cannabidiol (CBD) in an ongoing, expanded access program (EAP), which closely reflects clinical practice. We conducted an interim analysis of long-term efficacy and tolerability in patients with Lennox-Gastaut syndrome (LGS) or Dravet syndrome (DS) who received CBD treatment through December 2016. Methods Children and adults with LGS/DS taking stable doses of antiepileptic drugs (AEDs) at baseline were included from 25 EAP sites across the United States. During the 4-week baseline period, parents/caregivers kept diaries of all countable seizure types. Patients received a pharmaceutical formulation of highly purified CBD (Epidiolex®; 100 mg/mL) in oral solution at 2–10 mg/kg/day, titrated until tolerability limit or a maximum dose of 25–50 mg/kg/day. Patient visits were every 2–4 weeks. The percentage change from baseline in median monthly convulsive (ie, major motor) and total seizures was evaluated at 12-week intervals through 96 weeks. The percentages of patients who had ≥50%, ≥75%, and 100% reduction in monthly seizures relative to the baseline period were also evaluated. Adverse events (AEs) were monitored and summarized for the safety analysis set (SAS) through 144 weeks. Results Of the 607 patients in the SAS, 58 had DS and 94 had LGS (N = 152); 455 patients had other TREs. Twenty-eight percent of LGS/DS patients withdrew, primarily owing to lack of efficacy (20%). LGS/DS patients were taking a median of 3 (0–10) concomitant AEDs. Median treatment duration was 78.3 (range, 4.1–146.4) weeks. Between weeks 12 and 96, median CBD dose ranged from 21 to 25 mg/kg/day. At 12 weeks, add-on CBD reduced median monthly major motor seizures by 50% and total seizures by 44%, with consistent reductions in both seizure types through 96 weeks. At 12 weeks, the proportions of patients with ≥50%, ≥75%, and 100% reductions in major motor seizures were 53%, 23%, and 6%; the proportions with corresponding reductions in total seizures were 46%, 26%, and 5%. Responder rates for both seizure types were consistent through 96 weeks. CBD had an acceptable safety profile; the most common AEs were somnolence (30%) and diarrhea (24%). Conclusions Results from this interim analysis support add-on CBD as an effective long-term treatment option in LGS or DS.

Purpose Lennox-Gastaut syndrome (LGS) is a severe childhood-onset epileptic encephalopathy characterized by the presence of multiple types of intractable seizures, cognitive impairment, and specific electroencephalogram (EEG) patterns. The aim of this study was to investigate the electroclinical features of patients with LGS during adulthood. Methods We retrospectively identified the medical records of 20 patients aged over 18 years with a diagnosis of LGS from 3896 patients with epilepsy. Results Thirteen (65 %) patients were male. The mean age of the patients was 23.4 ± 7.1 (min-max; 18–43) years, and the mean follow-up period was 5.6 ± 4.5 (min-max; 1–14) years. The etiology was identified in 11 (55 %) patients. None of the patients achieved seizure freedom. The most prevalent seizure types were atypical absences in 14 (70 %) patients, tonic seizures in 13 (65 %) patients, and atonic seizures in 11 (55 %) patients. One (5 %) patient was diagnosed as having psychogenic non-epileptic seizures. Mental retardation was reported in all patients and only half of them could walk independently. All patients had drug-resistant seizures and 16 (80 %) patients were on polytherapy. A vagus nerve stimulator was implanted into ten (50 %) patients and five reported 50–80 % seizure reduction. Ketogenic diet was administered to two (10 %) patients and epilepsy surgery was performed in two (10 %) patients with no significant benefit. Conclusions Paying attention to all factors of seizure outcomes, cognitive impairment, and ambulatory status, all patients were dependent on caregivers for daily living abilities. LGS has life-long persistence with poor outcomes, even during adulthood.

Purpose To evaluate the long-term safety and seizure outcome in Japanese patients with Lennox–Gastaut syndrome (LGS) receiving adjunctive rufinamide therapy. Subjects and methods We conducted an open-label extension study following a 12-week multicenter, randomized, double-blind, placebo-controlled study of adjunctive rufinamide therapy in Japanese patients with LGS. Fifty-four patients participated in the extension study. Seizure frequency was evaluated until 52 weeks after the start of the extension study. Adverse events (AEs) were evaluated throughout both studies. Key findings Of the 54 patients, 41 (75.9%) completed the extension study. The median duration of exposure to rufinamide was 818.0 days in all 54 patients, and 38 patients (70.4%) received rufinamide for 2 years or more. The median percent change in the frequency of tonic–atonic seizures relative to the frequency at the start of the double-blind study was −39.3% (12 weeks), −40.6% (24 weeks), −46.8% (32 weeks), −47.6% (40 weeks), and −36.1% (52 weeks). Reduction of total seizure frequency was also maintained until 52 weeks. Frequent treatment-related AEs were somnolence (20.4%), decreased appetite (16.7%), transient seizure aggravation including status epilepticus (13.0%), vomiting (11.1%), and constipation (11.1%). Adverse events were mild or moderate, except for transient seizure aggravation in three patients. Adverse events resulting in discontinuation of rufinamide were decreased appetite, drug eruption, and worsening of underlying autism. When clinically notable weight loss was defined as a decrease ≥7% relative to baseline, 22 patients (40.7%) experienced weight loss at least once during long-term observation, although weight loss was reported as an AE in only three patients. Significance This study demonstrated a long-term benefit of rufinamide as adjunctive therapy for Japanese patients with LGS. Exacerbation of seizures and decreased appetite/weight loss should be monitored carefully.

Summary Objective To evaluate the effectiveness of rufinamide (RFM) in patients with Lennox–Gastaut Syndrome (LGS) compared to those with other epilepsy syndromes using time to treatment failure (retention rate) as the outcome measure. Methods In this retrospective cohort study, characteristics and outcomes of all patients receiving RFM in 2009 and 2010 were recorded. The primary outcome measure was RFM failure, defined as discontinuation of RFM or initiation of an additional antiepileptic therapy. The secondary outcome measure was discontinuation of RFM. Kaplan–Meier method survival curves were generated for time to RFM failure, for all patients and by the presence or absence of Lennox Gastaut Syndrome (LGS). The impact of age, seizure type, fast or slow drug titration, and concomitant therapy with valproate on retention rate were evaluated using Cox regression models. Results One hundred thirty-three patients were included, 39 (30%) of whom had LGS. For all patients, the probability of remaining on RFM without additional therapy was 45% at 12 months and 30% at 24 months. LGS diagnosis was an independent predictor of time to RFM failure (HR 0.51, 95% CI 0.31–0.83), with a median time to failure of 18 months in LGS compared to 6 months in all others ( p =0.006). Conclusions In a broad population of children with refractory epilepsy, around half will continue taking the medication for at least a year without additional therapy. Patients with LGS are two times more likely to continue RFM without additional therapy compared to those without LGS.

SummaryPurposeTo evaluate the efficacy, safety, and pharmacokinetics of rufinamide as an adjunctive therapy for patients with Lennox–Gastaut syndrome (LGS) in a randomized, double-blind, placebo-controlled trial.MethodsWe conducted a multicenter clinical trial with a 4-week baseline, a 2-week titration, a 10-week maintenance, and either a follow-up visit or entry into an open-label extension. Patients with LGS (4 to 30 years old) taking between one and three antiepileptic drugs were recruited. After the baseline period, patients were randomly assigned to rufinamide or placebo. The primary efficacy variable was the percent change in the tonic–atonic seizure frequency per 28 days.Key findingsOf the 59 patients, 29 were randomized to the rufinamide group and 30 to the placebo group. The frequency of epileptic seizures was significantly decreased in the rufinamide group than in the placebo group; the median percent change in frequency of tonic–atonic seizures was −24.2% and −3.3%, respectively, (p=0.003) and that of total seizures was −32.9% and −3.1%, respectively (p

The aim of this study was to evaluate the efficacy of the ketogenic diet (KD) on the clinical and electroencephalographic (EEG) features of Lennox-Gastaut syndrome (LGS) and explore the relationships between EEG changes and clinical efficacy.We retrospectively studied 47 patients with LGS who accepted KD therapy between May 2011 and May 2015. Clinical efficacy and EEG features such as background activity, abnormal interictal epileptic discharges (IEDs) and the discharge location were evaluated prior to and at 3 and 6 months after therapy. Responders were defined as ≥50% seizure reduction.At 3 months of treatment, 23 patients (48.9%) had ≥50% seizure reduction. Seven patients (14.9%) discontinued treatment between 3 and 6 months because of lack of efficacy or inability to adhere to the diet. At 6 months of treatment, 4 patients (10%) were seizure free, 5 (12.5%) had ≥90% seizure reduction, 12 (30%) had a reduction of 50-89%, and 19 (47.5%) had50% reduction. Patients with improved EEG background and reduced IEDs had an improved seizure reduction rate compared with patients without change in EEG background or IEDs (p0.01).The results show that the KD is effective in LGS. It can control seizures and improve EEG abnormalities. Early improvement in the EEG background and a reduction in IEDs may be predictors of a patient's response to diet.

Summary In this study, we describe three patients who each had an electroclinical overlap of two different epileptic encephalopathies (EE), with onset in a certain age period. Patient 1 had electroclinical features compatible with continuous spikes and waves during slow sleep (CSWSS) syndrome that changed into Lennox–Gastaut syndrome (LGS) (symptomatic, cause porencephalic cyst) at the age of 8.5 years. Patient 2 had LGS which evolved into CSWSS at the age of 6 years (symptomatic, cause polymicrogyria). The third patient had cryptogenic CSWSS syndrome at age the age of 7 years which evolved into LGS at the age of 7.5 years. All three patients could be considered to have two EE: CSWSS syndrome and LGS or to have had overlapping features of these epilepctic syndromes.

We herein investigated risk factors of pediatric acute encephalopathy (AE) regarding the hitherto uncharacterized genetic background of seizure susceptibility underlying the pathogenesis of AE. The study included 15 patients with a history of various types of AE in childhood. We undertook the mutational analysis of the neuronal sodium channel alpha 1 subunit (SCN1A) gene which is the most representative gene for hyperthermia-induced seizure susceptibility. Six patients (40%) had a positive family history of seizures or AE, especially febrile seizures, in first- or second-degree relatives. The SCN1A-R1575C mutation was detected in a patient with a history of acute encephalitis with refractory, repetitive partial seizures (AERRPS) and also in the patient's apparently healthy father. In the present study, dense familial seizure predisposition was present in the patients with AE. Although the presence of seizure susceptibility alone is insufficient to cause AE, it can exacerbate seizures and the subsequent development of inflammatory reactions in the brain when environmental factors are included. Genetic seizure susceptibility may contribute to some types of AE in childhood.

Objective To study the different epilepsy syndromes that included epileptic spasms (ES) in clusters without hypsarrhythmia (WoH). Methods Between 2/1990 and 7/2013, we registered 48 patients with the electroclinical diagnostic criteria of ES in clusters WoH. Results We recognized two subgroups. In the first subgroup of 30 patients, ES started at a mean age of 10.6 months (range, 2–40 months). Ictal EEG recordings showed diffuse high-amplitude slow waves in 15 patients, diffuse slow waves followed by voltage attenuation in six patients, diffuse fast rhythms in five, diffuse slow waves with superimposed fast rhythms in three, and diffuse sharp waves in one. In the second subgroup of 18 patients, nine had electroclinical features of Lennox–Gastaut syndrome, four had epilepsy with myoclonic and atonic seizures, two had Dravet syndrome, one 6-year-old boy had a non-convulsive status epilepticus characterized by atypical absences associated with ES, one had epilepsy with migrating seizures of infancy, and one patient had clinical features of subacute sclerosing panencephalitis with ES. ES started at a mean age of 6.3 years (range, 0.5–13 years). The ictal EEG recording during the ES showed diffuse fast rhythms in 10 cases, diffuse slow waves with superimposed fast rhythms in four, and diffuse slow waves in four. Conclusion Our study shows two subgroups of children with ESWoH. The first subgroup had a well-defined electroclinical syndrome predominantly in infancy, and in the second subgroup ES was one more seizure type associated with an epileptic encephalopathy other than West syndrome predominantly occurring in childhood.

Objectives Lennox–Gastaut syndrome (LGS) is a severe epilepsy of childhood onset associated with intellectual disability and multiple seizure types. Characteristic interictal electrographic discharges include generalized paroxysmal fast activity and slow spike and wave, which we have previously shown recruit widespread areas of association cortex. We wished to determine whether patients with Lennox–Gastaut syndrome (LGS) have changes in cerebral volumes that match this pattern of cortical recruitment. Methods High resolution T1 weighted structural MRI was collected from 10 patients with LGS and 10 age and sex matched controls. Voxel-based morphometry (VBM) was used to compare tissue volumes across the whole brain (grey matter, white matter and CSF) and pontine volume between patients and controls, as well as to identify other regions of maximal tissue loss. Results LGS patients showed a significant decrease in whole brain volume compared to controls. Cortical atrophy was prominent in the mesial frontal region and bilateral anterior temporal poles. White matter atrophy was widespread and included peri-central and premotor regions. Atrophy was prominent in the pons, particularly in the region of the reticular formation. Grey matter atrophy trended to progress with age. Significance Grey and white matter atrophy are a feature of Lennox–Gastaut syndrome. Grey matter atrophy is apparent in the mesial frontal lobe suggesting this region may be an important node in the epilepsy network of LGS. Atrophy maximal in the pons and cerebellum mimics the patterns of seizure spread that has been previously observed during tonic seizures. This supports the idea that the pons is a key part of the epilepsy network in LGS.

Summary Purpose Lennox–Gastaut syndrome (LGS) is a severe epileptic encephalopathy with complex etiology. To explore possible genetic predispositions and causes of LGS, we have searched for copy number variants (CNVs). Methods We studied 21 patients with LGS or LGS-like epilepsy for CNVs using whole-genome array comparative genomic hybridization (aCGH). Key findings Eight patients (38%) carried rare CNVs that might contribute to their phenotype. The pathogenicity could be questioned in some of them, but in four patients (19%) a causative role was considered highly probable. Three had CNVs and clinical features consistent with known genetic syndromes: 22q13.3 deletion, 2q23.1 deletion, and MECP2 duplication. Significance There is a high frequency of rare CNVs in adult patients with LGS-like epilepsy. The phenotypes of these background disorders may be obscured by the effects of intractable seizures and massive antiepileptic drug treatment. Previously, syndromic disorders were primarily identified by their clinical features; however, a genome wide approach with identification of the genotype might shed light on the phenotype.

Precise localization of ictal onset zones is of great clinical importance for successful surgery in patients with intractable drug-resistant epilepsy. Time delay analysis has been one of the most reliable and most widely used computational electroencephalogram (EEG) analysis methods for localizing ictal onset zones. However, the majority of previous studies have only been applied to the localization of ictal onset zones in focal epilepsy. In the present study, we analyzed intracranial EEG (iEEG) recordings acquired from patients with Lennox-Gaustaut syndrome (LGS), which is a type of intractable, pediatric, secondary generalized epilepsies with bilaterally synchronous ictal epileptiform discharges. To estimate the ictal onset zones from ictal iEEG recordings, we estimated time delays among iEEG signals based on the information theoretical approach. The results of the time delay analysis applied to the iEEG data of four successfully treated LGS patients corresponded well with the surgical resection areas identified by experienced epileptologists and multiple neuroimaging modalities, suggesting that the time delay analysis may provide useful information on the precise locations of ictal onset zones prior to epilepsy surgery in LGS patients.

We describe a case of a patient with Lennox-Gastaut syndrome who had asystole and sinus bradycardia during interictal epileptiform abnormalities on EEG. Video-EEG/EKG monitoring prior to corpus callosotomy recorded consistent prolongation of the R-R interval on the EKG during bursts of epileptiform abnormalities (generalized paroxysmal fast activity), which became transiently more pronounced after surgery. These findings reveal that interictal epileptiform abnormalities may cause significant cardiac arrhythmias in some individuals.