Interictal EEG Patterns Research Articles

Which psychogenic nonepileptic seizure (PNES) patients are more likely to be treated with anti-seizure medications?

BackgroundThe average time for psychogenic nonepileptic seizures (PNES) diagnosis is about 7.5 years. Many patients receive inadequate treatment and sometimes even life-threatening treatments such as tracheal intubation during this time. PurposeTo determine the risk factors for misdiagnosis of PNES as Epilepsy. MethodsThe medical records of patients who underwent video-electroencephalogram (EEG) monitoring were reviewed retrospectively. Patients who had PNES without epileptic seizures (ES) were included in this study. Baseline personal and monitoring characteristics were collected. The patients were then divided into two groups based on their therapeutic status. Patients in the treatment group were again divided into two groups based on the number of anti-seizure medications (ASM) they were treated with. ResultsFifty-seven patients diagnosed with PNES were included in this study. Thirty-seven patients were under treatment, and 20 patients were not under treatment at the time of monitoring. Motor seizures, abnormal interictal EEG patterns, and pathological brain imaging findings were more frequent among patients in the treatment group (p<0.05). Patients with motor seizures were more likely to be treated with multiple ASM than patients with only dialeptic nonmotor seizures (p<0.05). Lastly, patients in the treatment group were monitored longer and had fewer seizures during monitoring (p<0.05). ConclusionPNES patients with abnormal EEG patterns and pathological brain imaging findings are more likely to be treated with ASM. The pure dialeptic nature of seizures is less likely to be misdiagnosed as ES. In addition, patients with such seizures are less likely to be treated with multiple treatment lines.

Electroclinical Landscape of Infantile Epileptic Spasms Syndrome.

To elucidate the electroclinical characteristics of infantile epileptic spasms syndrome (IESS) and to determine any potential association among these with underlying etiologies and response to therapy. Sixty-eight, treatment-naive children with IESS underwent long-term video electroencephalogram (EEG) recording, which was used to characterize the semiology, ictal, and inter-ictal EEG patterns. Children were further followed up to assess electroclinical predictors of etiologies and short-term therapeutic response. Of 68 children enrolled (69% boys), the median age at enrollment was 10.5 mo (IQR-8). Eighty-eight percent of children had flexor spasms, followed by mixed (7%) and extensor (4.4%). Asymmetrical spasms were noted in 17.6% children, and all of them had underlying structural etiology. Two children had the status of epileptic spasms. In the present cohort, authors recognized five distinct ictal EEG correlates of epileptic spasms; the frontocentral dominant slow wave was the most prevalent (32%), followed by the generalized slow-wave complex with superimposed fast rhythm in 29.4%. The occipital dominant slow wave complex was a peculiar pattern in 16%. The major underlying etiologies were hypoxic-ischemic brain injuries (36.7%) and neonatal hypoglycemic brain injuries (22%). Besides asymmetric spasms, authors could not identify any significant association among electroclinical characteristics, underlying etiologies and response to therapy in this study. The electroclinical landscape of IESS is peculiar and diverse in developing countries. The presence of asymmetrical spasms indicated underlying structural etiology.

Learn how to interpret and use intracranial EEG findings.

Epilepsy surgery is the therapy of choice for many patients with drug-resistant focal epilepsy. Recognizing and describing ictal and interictal patterns with intracranial electroencephalography (EEG) recordings is important in order to most efficiently leverage advantages of this technique to accurately delineate the seizure-onset zone before undergoing surgery. In this seminar in epileptology, we address learning objective "1.4.11 Recognize and describe ictal and interictal patterns with intracranial recordings" of the International League against Epilepsy curriculum for epileptologists. We will review principal considerations of the implantation planning, summarize the literature for the most relevant ictal and interictal EEG patterns within and beyond the Berger frequency spectrum, review invasive stimulation for seizure and functional mapping, discuss caveats in the interpretation of intracranial EEG findings, provide an overview on special considerations in children and in subdural grids/strips, and review available quantitative/signal analysis approaches. To be as practically oriented as possible, we will provide a mini atlas of the most frequent EEG patterns, highlight pearls for its not infrequently challenging interpretation, and conclude with two illustrative case examples. This article shall serve as a useful learning resource for trainees in clinical neurophysiology/epileptology by providing a basic understanding on the concepts of invasive intracranial EEG.

Clinical characteristics and surgical outcomes in children with mild malformation of cortical development and oligodendroglial hyperplasia in epilepsy.

Mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE) is a new and rare histopathological entity of cortical developmental malformations. The clinical characteristics of MOGHE remain challenging. Children with histologically confirmed MOGHE were retrospectively studied. The clinical findings, electroclinical and imaging features, and postoperative outcomes were analyzed, and previously published studies were reviewed up to June 2022. Thirty-seven children were included in our cohort. Clinical characteristics included early onset in infancy (94.6% before 3 years), multiple seizure types, and moderate or severe delay. Epileptic spasm is the most common seizure type and initial manifestation. The lesions were mainly multilobar (59.5% multiple lobes and 8.1% hemispheres), and predominance in the frontal lobe was observed. The interictal EEG pattern was circumscribed or widespread. The prominent MRI characteristics were cortical thickening, cortical/subcortical hyperintense T2/FLAIR signal, and blurring at the GM and WM transition. Among the 21 children followed up for more than 1 year after surgery, 76.2% were seizure-free. Preoperative interictal circumscribed discharges and larger resections were significantly associated with a good postoperative outcome. The clinical features of 113 patients in the reviewed studies were similar to those we reported, but the lesions were mainly unilobar (73.5%) and Engel I was achieved in only 54.2% after surgery. Distinct clinical characteristics in MOGHE, especially age at onset, epileptic spasm, and age-related MRI characteristics, can help in early diagnosis. Preoperative interictal discharge and surgical strategy may be predictors of postoperative outcomes.

Seizures in the Contralateral hemisphere in Rasmussen Encephalitis after Disconnective hemispherectomy – True or False lateralizing? (P13-1.010)

<h3>Objective:</h3> To describe a case that highlights diagnostic and treatment challenges when seizures recur after disconnective hemispherectomy. <h3>Background:</h3> Recurrence of seizures after hemispheric disconnection warrants careful evaluation to assess candidacy for additional surgery. Interpretation of EEG in the setting of post-hemispheric disconnection poses special challenges. <h3>Design/Methods:</h3> Retrospective chart review and literature search. <h3>Results:</h3> A 10-year-old right-handed girl presented with focal drug-resistant epilepsy from age 7 years. Initially, she had left face/arm motor seizures, but over the years developed other seizure types - myoclonic, generalized tonic-clonic, dialeptic, and atonic head drop. Neurological examination showed no focal motor deficit. Interictal EEG with abundant right frontocentral and secondary bilateral synchronous discharges, while ictally had a diffuse non-localized pattern. Serial MRI brain showed progressive right hemispheric atrophy predominantly around the perisylvian and perirolandic regions. She met the criteria for diagnosis of Rasmussen encephalitis. Due to the poor quality of life from daily seizures, after much contemplation, a right disconnective hemispherectomy was done. Pathology of brain tissue confirmed Rasmussen encephalitis. Her seizures recurred around 4 months post-surgery. Interictal EEG showed abundant independent epileptiform discharges from both hemispheres. Ictal EEG showed ictal patterns over the left hemisphere. Post-operative brain MRI showed no evidence for residual hemispheric disconnection. A possibility of bilateral Rasmussen encephalitis versus a false lateralizing EEG pattern with seizures still arising from the operated hemisphere was considered. She underwent a re-do right anatomic hemispherectomy and has been seizure free since surgery at a 2-year follow-up. Post-op EEG showed no epileptiform abnormalities over the left hemisphere. <h3>Conclusions:</h3> In the post-hemispherectomy setting, both interictal and ictal EEG patterns may be falsely lateralizing, and persistent seizures should raise the suspicion of an incomplete disconnection. Looking for an overt connection on MRI can help, but the lack of one is not always a reliable marker of complete disconnection. <b>Disclosure:</b> Dr. Natteru has nothing to disclose. Dr. Alzahrany has nothing to disclose. William Bingaman has nothing to disclose. Dr. Naduvil Valappil has nothing to disclose.

Interictal pattern on scalp electroencephalogram predicts excellent surgical outcome of epilepsy caused by focal cortical dysplasia.

ObjectiveFocal cortical dysplasia (FCD) represents an essential cause of drug‐resistant epilepsy with surgery as an effective treatment option. This study aimed to identify the important predictors of favorable surgical outcomes and the impact of the interictal scalp electroencephalogram (EEG) patterns in predicting postsurgical seizure outcomes.MethodsWe retrospectively evaluated 210 consecutive patients between 2015 and 2019. They were diagnosed with FCD by pathology, underwent resection, and had at least one year of postsurgical follow‐up. Predictors of seizure freedom were analyzed.ResultsBased on the information at the latest follow‐up, seizure outcome was classified as Engel Class I (seizure‐free) in 81.4% and Engel Class II‐IV (non‐seizure‐free) in 18.6% of patients. There were 43, 105, and 62 cases of FCD type I, type II, and type III, respectively. The interictal EEG showed a repetitive discharge pattern (REDP) in 87 (41.4%) patients, polyspike discharge pattern (PDP) in 41 (19.5%), and the coexistence of REDP and PDP in the same location in 32 (15.2%) patients. The analyzed patterns in order of frequency were repetitive discharges lasting 5 seconds or more (32.4%); polyspikes (16.7%); RED type 1 (11.4%); continuous epileptiform discharges occupying >80% of the recording (11.4%); RED type 2 (6.2%); brushes (3.3%); focal, fast, continuous spikes (2.4%); focal fast rhythmic epileptiform discharges (1.43%); and frequent rhythmic bursting epileptiform activity (1.4%). The coexistence of REDP and PDP in the same location on scalp EEG and complete resection of the assumed epileptogenic zone (EZ) was independently associated with favorable postsurgical prognosis.SignificanceResective epilepsy surgery for intractable epilepsy caused by FCD has favorable outcomes. Interictal scalp EEG patterns were revealed to be predictive of excellent surgical outcomes and may help clinical decision‐making and enable better presurgical evaluation.

SYNGAP1-DEE: A visual sensitive epilepsy

ObjectiveTo further delineate the electroclinical features of individuals with SYNGAP1 pathogenic variants. MethodsParticipants with pathogenic SYNGAP1 variants and available video-electroencephalogram (EEG) recordings were recruited within five European epilepsy reference centers. We obtained molecular and clinical data, analyzed EEG recordings and archived video-EEGs of seizures and detailed characteristics of interictal and ictal EEG patterns for every patient. ResultsWe recruited 15 previously unreported patients and analyzed 72 EEGs. Two distinct EEG patterns emerged, both triggered by eye closure. Pattern 1 (14/15 individuals) consisted of rhythmic posterior/diffuse delta waves appearing with eye-closure and persisting until eye opening (strongly suggestive of fixation-off sensitivity). Pattern 2 (9/15 individuals) consisted of diffuse polyspike-and-wave discharges triggered by eye closure (eye-closure sensitivity). Both patterns presented in 8/15. Including archived video-EEG clips of seizures from 9/15 patients, we analyzed 254 seizures. Of 224 seizures experienced while awake, 161 (72%) occurred at or following eye closure. In 119/161, pattern 1 preceded an atypical absence, myoclonic seizure or myoclonic absence; in 42/161, pattern 2 was associated with eyelid myoclonia, absences and myoclonic or atonic seizures. ConclusionsFixation-off and eye closure were the main triggers for seizures in this SYNGAP1 cohort. SignificanceCombining these clinical and electroencephalographic features could help guide genetic diagnosis.

Acthar® Gel (repository corticotropin injection) dose–response relationships in an animal model of epileptic spasms

Studies were undertaken to evaluate the effectiveness of Acthar® Gel (repository corticotropin injection [RCI]) in the tetrodotoxin (TTX) model of early-life-induced epileptic spasms. Repository corticotropin injection (RCI) is widely used in the United States to treat infantile spasms. A major component of RCI is N25 deamidated ACTH. Additionally, we hoped to provide some insight into the possible role circulating corticosteroids play in spasm cessation by comparing the RCI dose–response relationships for spasm suppression to RCI-induced corticosterone release from the adrenal gland. Spasms were induced by chronic TTX infusion into the neocortex beginning on postnatal day 11. Repository corticotropin injection (RCI) dosages were between 8 and 32 IU/kg/day. Drug titration protocols were used, and comparisons were made to injections of a vehicle gel. Video/EEG recordings (24/7) monitored the drug’s effects continuously for up to 2 months. Tetrodotoxin (TTX)-infused control rats were monitored for the same period of time. In separate experiments, the same dosages of RCI were given to rats and 1 h later plasma was collected and assayed for corticosterone. A parallel study compared the effects of 1-day and 10-day RCI treatments on circulating corticosterone. Results showed that RCI was ineffective at dosages of 8, 12, and 16 IU/kg/day but eliminated spasms in 66% of animals treated with 24 or 32 IU/kg/day. Treating animals with 32 IU/kg/day alone produced the same degree of spasms suppression as observed during the titration protocols. In rats that had hypsarrhythmia-like activity, RCI eliminated this abnormal interictal EEG pattern in all rats that became seizure-free. In terms of plasma corticosterone, 1- and 10-day treatments with RCI produced similar increases in this hormone and the levels increased linearly with increasing dosages of RCI. This stood in sharp contrast to the sigmoid-like dose–response curve for decreases in spasm counts. Our results further validate the TTX model as relevant for the study of infantile spasms. The model should be useful for investigating how RCI acts to eliminate seizures and hypsarrhythmia. Dose–response results suggest that either very high concentrations of circulating corticosteroids are required to abolish spasms or RCI acts through a different mechanism.

Deep active learning for interictal ictal injury continuum EEG patterns

ObjectivesSeizures and seizure-like electroencephalography (EEG) patterns, collectively referred to as “ictal interictal injury continuum” (IIIC) patterns, are commonly encountered in critically ill patients. Automated detection is important for patient care and to enable research. However, training accurate detectors requires a large labeled dataset. Active Learning (AL) may help select informative examples to label, but the optimal AL approach remains unclear. MethodsWe assembled >200,000 h of EEG from 1,454 hospitalized patients. From these, we collected 9,808 labeled and 120,000 unlabeled 10-second EEG segments. Labels included 6 IIIC patterns. In each AL iteration, a Dense-Net Convolutional Neural Network (CNN) learned vector representations for EEG segments using available labels, which were used to create a 2D embedding map. Nearest-neighbor label spreading within the embedding map was used to create additional pseudo-labeled data. A second Dense-Net was trained using real- and pseudo-labels. We evaluated several strategies for selecting candidate points for experts to label next. Finally, we compared two methods for class balancing within queries: standard balanced-based querying (SBBQ), and high confidence spread-based balanced querying (HCSBBQ). ResultsOur results show: 1) Label spreading increased convergence speed for AL. 2) All query criteria produced similar results to random sampling. 3) HCSBBQ query balancing performed best. Using label spreading and HCSBBQ query balancing, we were able to train models approaching expert-level performance across all pattern categories after obtaining ∼7000 expert labels. ConclusionOur results provide guidance regarding the use of AL to efficiently label large EEG datasets in critically ill patients.

Inter-ictal EEG patterns in malformations of cortical development and epilepsy

ObjectivesMalformations of cortical Development (MCDs) are associated with refractory epilepsy. We evaluated scalp inter-ictal EEG patterns in various types of MCD, and its association with clinical features and seizure control. Patients and methodsRetrospective analysis of demographic, clinical, inter-ictal EEG and seizure outcome data of 665 patients with epilepsy and MCD with at least two years follow up was performed. ResultsAverage age of study population was 15.95 ± 10.79 years with 291(43.8 %) women. Multiregional spikes were more common in children (22.7 % vs 8.5; p < 0.001), if age of onset of epilepsy was <2 years (21.8 % vs 11.4 %; p = 0.001) and polymicrogyria (12.1 % vs 37.3 %; p < 0.001). Generalized epileptiform discharges were more frequent in patients with developmental delay (24.7 % vs 12.6 %; p < 0.001); and were associated with lissencephaly(14.0 % vs 59.3 %; p < 0.001) and heterotopias(14.5 % vs 34.9 %;p = 0.002). Regional spikes were more common if age of onset of epilepsy is >2 years (26.2 % vs 38.4 %; p = 0.003), and also in FCD (17.1 % vs 42.6 %; p < 0.001). At latest follow-up, 151(22.7 %) patients were seizure free; 401(60.7 %) had refractory epilepsy and the rest had remissions with relapse. No association was found between inter-ictal EEG patterns and seizure control. ConclusionIn patients with MCD, generalized epileptiform discharges were associated with developmental delay, lissencephaly and heterotopias. Regional spikes were frequent in FCD while multiregional spikes in children and polymicrogyria. Inter-ictal EEG patterns did not influence seizure outcome.

The clinical phenotypes and genetic characteristics of seven epilepsy patients related to heterozygous DEPDC5 variants in China

ObjectiveDEPDC5 together with NPRL2 and NPRL3 forms the GATOR1 which plays an important role in the the mechanistic target of rapamycin (mTOR) pathway. Deregulation of mTOR signalling has been associated to various neurological conditions, including epilepsy. Variants in the gene encoding GATOR1 complex, especially in DEPDC5, have been implicated in the pathogensis of several focal epilepsies. While there was little report on the electroencephalogram (EEG) feature of DEPDC5 related epilepsy, we decided to investigate the specific EEG pattern and the prognosis of DEPDC5 related epilepsy.MethodsThe records of 546 epilepsy patients with unknown causes who were admitted in Xijing Hospital and underwent whole exome sequencing (WES) from 2015 to 2019 were retrospectively reviewed. Finally, the clinical data of these 7 patients with DEPDC5 variants were collected in this study. We analyzed their clinical manifestations, EEG and magnetic resonance imaging (MRI).ResultsSeven DEPDC5 variants, including six novel mutations, were identified in seven individuals with focal epilepsy. Among these patients, one had family history. Four showed specific interictal EEG patterns, periodic-like sharp waves or spike waves, were found in four patients. Five out of seven patients (71.4%) were well-controlled by anti-epilepsy drugs while two patients with sleep-related hypermotor epilepsy had either drug resistance or relapse of epilepsy.ConclusionDEPDC5 variants were related to focal epilepsy in patients with or without family history. The EEG abnormalities of DEPDC5 related epilepsy were heterogeneous among different patients, while periodic-like sharp waves or spike waves might be the most characteristic interictal EEG pattern for DEPDC5 related epilepsies. In this study the prognosis of DEPDC5 related epilepsy was similar to other epilepsies. DEPDC5 variants may not predict the prognosis so far.

Refractory epilepsy with epileptic spasms: Clinical characteristics and predictors of outcome after surgery

Epileptic spasms (ES) are a distinct seizure type with “uncertain” onset and refractory to medical management. To determine clinical profile and predictors of outcome of surgery in patients with refractory epilepsy with ES as the only/predominant seizure type. Clinical, inter-ictal and ictal EEG, MRI brain, FDG PET and ictal SPECT data of 65 patients with refractory epilepsy with ES as the only/predominant seizure type, who underwent epilepsy surgery and had at least two years post-surgical follow-up was analysed. Of the 65 subjects included, 40 were males; 36 55.4%) had onset of epilepsy before 2 years. The mean duration of epilepsy was 7.46 ± 6 years. Fifty four(83.1%) had daily seizures at presentation. Only ES as the manifestation of epilepsy was present in 16(24.6%) while 49(75.4%) had multiple types of seizure with ES as major seizure type. MRI was normal in 9. Forty eight (73.8%) had mental retardation and 62(95.4%) had poor quality of life. Inter-ictal EEG was multifocal/generalized pattern in 50(76.9%) and ictal EEG onset was generalized in 26(40%). PET/ictal SPECT were lateralizing/localizing in 40(61.5%) and 18 (27.7%) respectively. Most common surgery performed was lesionectomy(53.8%) and most common histopathological diagnosis was focal cortical dysplasia (56.9%); 38 (58.5%) were seizure free at last follow-up. Lesion on MRI and functional hemispherotomy were associated with favourable outcome (β = 0.415, p = 0.001) while lesionectomy(β = −0.282, p = 0.015) and generalized inter-ictal EEG patterns (β = −1.084, p = <0.001) were associated with poor outcome. Refractory epilepsy with ES carries significant morbidity; favorable outcome can be achieved in 58% after epilepsy surgery.

Seizure Outcome and Its Prognostic Predictors After Hemispherotomy in Children With Refractory Epilepsy in a Chinese Pediatric Epileptic Center.

Object: To explore the post-hemispherotomy seizure outcome and its prognostic predictors in children with refractory epilepsy.Methods: We reviewed 83 consecutive child patients with refractory epilepsy who underwent a hemispherectomy from June 2014 to January 2017 at our Pediatric Epilepsy Center. Demographic, clinical, EEG, neuroimaging, and surgical data were collected. Seizure outcome data were collected via outpatient clinics as well as telephone visits and were graded according to Engel criteria. Logistic regression model and Cox proportional hazard regression model were, respectively, applied to explore the related factors predicting the seizure outcomes of children after a hemispherotomy.Results: Of the 83 patients, 55 (63.2%) were male. The mean seizure onset age was 1.9 years (0–8.7 years), and the mean surgery age was 5 years (0.8–14 years). At a mean follow-up of 3 years, 69 children (83.1%) were seizure free, and 14 (16.9%) exhibited seizure recurrence. In a univariate analysis, whether or not considering follow-up time, a non-lateralized interictal EEG pattern, bilateral PET abnormalities and acute postoperative seizures (APOS) could all predict poor seizure outcomes post-hemispherotomy. Bilateral PET abnormalities were independently correlated with unfavorable seizure outcomes in the multivariate Logistic regression analysis (Odds ratio(OR) = 13.05, 95%CI = 1.52–112.29, P = 0.019) and in the multivariate Cox proportional hazard analysis(OR = 13.99, 95%CI = 2.75–71.17, P = 0.001).Conclusions: Child epileptic patients with bilateral PET abnormalities may have poor seizure outcomes after a hemispherotomy procedure. This study will facilitate better candidate selection for hemispherotomies and early identification of unfavorable seizure outcomes.

Hypsarrhythmia is associated with widespread, asymmetric cerebral hypermetabolism

PurposeHypsarrhythmia is the interictal EEG pattern most often associated with infantile spasms. We set out to evaluate the metabolic impact of hypsarrhythmia among patients with infantile spasms by contrasting regional cerebral metabolic activity among children with and without hypsarrhythmia. MethodsPatients with video-EEG confirmed infantile spasms who underwent simultaneous interictal EEG and FDG-PET as part of a surgical evaluation were retrospectively identified. Pons-normalized relative cerebral metabolic activity (RCA) was ascertained in 18 cortical and 6 subcortical pre-specified regions of interest (ROIs). ResultsWe identified 63 patients with infantile spasms who underwent simultaneous EEG/PET, including children with hypsarrhythmia (n = 9), high-voltage EEG background (n = 20), and multifocal independent spike discharges (MISD) (n = 34). Among them, a putative epileptogenic zone was identified within the left-hemisphere only (n = 27), right-hemisphere only (n = 20), or assumed to be bilateral (n = 16). After adjustment for age at PET, the presence of hypsarrhythmia was associated with hypermetabolism in 11 of 18 cortical ROI’s. After adjustment for lateralized epileptogenic zones, the association between hypsarrhythmia and hypermetabolism was generally stronger within the left hemisphere. ConclusionHypsarrhythmia is associated with widespread—and curiously left more than right—elevations in pons-normalized RCA, which is not evident on routine clinical review of individual PET studies. This study suggests that hypsarrhythmia may be a quasi-ictal phenomenon based on widespread and usually bilateral cortical hypermetabolism.

Concordance between the interictal focal EEG pattern and MRI lesions as a predictor of a favorable surgical outcome in patients with epileptic spasms: a Chinese study.

The aim of this study was to evaluate the electro-clinical features, etiology, treatment, and postsurgical seizure outcomes in patients with intractable epileptic spasms (ESs). The authors retrospectively studied the medical records of all patients who had presented with medically intractable ESs and had undergone surgery in the period between October 2009 and August 2015. The interictal electroencephalography (EEG) pattern, MRI studies, magnetoencephalography findings, and postsurgical seizure outcomes were compared. Twenty-six patients, 12 boys and 14 girls (age range 3-22 years), were eligible for study inclusion. Of these 26 patients, 84.6% (22) presented with multiple seizure types including partial seizures (PSs) independent of the ESs (30.8%); ESs followed by tonic seizures (30.8%); myoclonic seizures (19.2%); tonic seizures (19.2%); ESs followed by PSs (19.2%); focal seizures with secondary generalization (15.4%); atypical absence (11.5%); PSs followed by ESs (7.7%); and myoclonic followed by tonic seizures (7.7%). Seventeen patients underwent multilobar resection and 9 underwent unilobar resection. At the last follow-up (mean 36.6 months), 42.3% of patients were seizure free (outcome classification [OC] 1), 23.1% had > 50% reduction in seizure frequency (OC2-OC4), and 34.6% had < 50% reduction in seizure frequency or no improvement (OC5 and OC6). Predictors of favorable outcomes included an interictal focal EEG pattern and concordance between interictal EEG and MRI-demonstrated lesions (p = 0.001 and 0.004, respectively). A favorable surgical outcome is achievable in a highly select group of patients with ESs secondary to structural lesions. Interictal EEG can help in identifying patients with the potential for favorable resective outcomes.

Chapter 1 - Generalized epilepsies

Idiopathic generalized epilepsies (IGE) are characterized by normal background EEG activity and generalized interictal spike-and-wave discharges in the absence of any evidence of brain lesion. Absence epilepsies are the prototypes of IGEs. In childhood and juvenile absence epilepsies, by definition, all patients manifest absence seizures associated with an EEG pattern of generalized spike-wave (GSW) discharges. In juvenile myoclonic epilepsy, myoclonic jerks, usually affecting shoulders and arms bilaterally and appearing upon awakening, are the most characteristic clinical feature. Myoclonic jerks are accompanied on the EEG by generalized spike/polyspike-and-wave (GSW, GPWS) complexes at 3.5-6Hz. Idiopathic generalized epilepsy with generalized tonic-clonic seizures only is a broad and nonspecific category including all patients with generalized tonic-clonic seizures and an interictal EEG pattern of GSW discharges. Despite the strong heritability and the recent advances in genetic technology, the genetic basis of IGEs remains largely elusive and only in a small minority of patients with classic IGE phenotypes is a monogenic cause identified. Early myoclonic encephalopathy (EME), early infantile encephalopathy with suppression bursts, West syndrome, and Lennox-Gastaut syndrome, once classified among the generalized epilepsies, are now considered to be epileptic encephalopathies. Among them, only Lennox-Gastaut syndrome is characterized by prominent generalized clinical and EEG features.

Use of Subtemporal Electrode Chains and Their Contribution to Presurgical Evaluation

ABSTRACTSubtemporal electrode chains are part of the international 10-10 system. Since 2012, they have been routinely used at our institution in adult patients with intractable epilepsy who are undergoing video EEG evaluation for epilepsy surgery. In 2016, this was extended to the pediatric population. However, there are few data regarding the utility of these electrodes. We performed a retrospective study to investigate the sensitivity and specificity for detection and lateralization of an ictal EEG pattern in patients with temporal lobe epilepsy. Neurophysiologists and EEG technologists were randomly shown samples containing interictal EEG or ictal patterns in standard biploar montage (anterior-posterior bipolar with international 10-20 electrodes only), modified bipolar montage with subtemporal chains, or modified bipolar montage with T1 and T2 electrodes added. Subtemporal chains improved sensitivity compared with standard bipolar, but they also reduced the specificity. T1 and T2 electrodes showed a nonsignificant trend towards improved sensitivity and specificity compared with standard bipolar. There was no difference in sensitivity for correct lateralization among the three montages.

Functional hemispherectomy is safe and effective in adult patients with epilepsy

IntroductionFunctional hemispherectomy (FH) is a well-established therapeutic option for children with epilepsy with parenchymal damage confined to one hemisphere, yet its application in adults remains rare. The intention of our study was to investigate postoperative clinical and epileptological outcome in adults who received FH for intractable epilepsy. Materials and methodsWe retrospectively analyzed 12 adult patients (18–56years) with intractable epilepsy due to unihemispheric pathology. All patients underwent FH. Postoperative neurological and cognitive outcome as well as seizure status were evaluated with a mean follow-up period of 4.9years. ResultsTen patients (83%) were seizure-free (Engel I), and two (17%) had recurrent seizures at last follow-up. Apart from one patient requiring operative revision for bone flap infection, no perioperative morbidity or mortality occurred. Postoperative functional assessment revealed deterioration of motor function in 7 patients, whereas 5 remained unchanged. Language was unchanged in 8 patients. The absence of background slowing in preoperative electroencephalogram (EEG) as well as ictal and interictal EEG patterns located ipsilateral to the side of surgery was associated with favorable seizure outcome. ConclusionFavorable seizure control and acceptable functional outcome can be achieved by FH in adults with intractable epilepsy. The risk of postoperative deficits is moderate and even older patients are able to manage postoperative motor impairment. Therefore, FH should be considered in case of unihemispheric lesions also in adults.

Seizure type and interictal epileptiform EEG patterns in Nigerians

Seizure type and interictal epileptiform EEG patterns in Nigerians

The new categorizing system of interictal EEG in pediatric epilepsy

Objective: We aimed to classifying of interictal EEG patterns in patients with pediatric epilepsy and determine the effectiveness of this simple EEG categorization. Methods: We retrospectively reviewed initial EEGs of 200 children with epilepsy. Two epileptologists reviewed them blindly by using 2 interictal EEG features: organization of the background activity and a morphology/topography of epileptiform discharges. These patterns relate to categories: (1) familial epilepsies, (2) genetic generalized epilepsies, (3) self limited epilepsies, (4) epilepsies with encephalopathy, and (5) focal structural epilepsies. From medical records, demographic features, brain imaging findings, response to therapy, and developmental outcome were analyzed. Results: Among 200 EEGs, the reviewers agreed on 187 (93.5%) EEGs and disagreed on 13 (6.5%) by categorizing the EEGs in different EEG groups. Interobserver agreement was high (κ = 0,91). Children who had normal background (pattern 1) were more likely to be seizure-free and had normal development and neurological examination than the other groups (p<0.0001). Children with pattern 2, stereotyped generalized spike-waves and a normal background, were likely to have normal MRI (p=0.004), normal development and neurological examination (p=0.017) than the other groups. Children who showed multifocal pleomorphic spikes and slow background on EEG (pattern 4) were more likely to have abnormal development (p<0.0001), neurological examination (p<0.0001) and MRI (p=0.006) and least likely to be seizure-free (p<0.0001) than the other groups. Children who showed focal pleomorphic spikes and slowing on EEG (pattern 5) were more likely to show abnormal MRI (p=0.015) and abnormal development (p=0.005) than the other groups. Conclusion: The simple categorization of interictal EEG abnormalities in children was firstly reported by Kim et al. at a pilot study. We also show in a large series, this classification could be helpful for educational tool, clinical evaluation, and to triage between patients requiring urgent evaluation or avoiding unnecessary procedures.