In Search of a Common Language: The Standardized Electrode Nomenclature for Stereoelectroencephalography Applications.

PURPOSE: Stereoelectroencephalography (SEEG) is widely performed on individuals with medically refractory epilepsy for whom invasive seizure localization is desired. Despite increasing adoption in many centers across the world, no standardized electrode naming convention exists, generating confusion among both clinical and research teams. METHODS: We have developed a novel nomenclature, named the Standardized Electrode Nomenclature for SEEG Applications system. Concise, unique, informative, and unambiguous labels provide information about entry point, deep targets, and relationships between electrodes. Inter-rater agreement was evaluated by comparing original electrode names from 10 randomly sampled cases (including 136 electrodes) with those prospectively assigned by four additional blinded raters. RESULTS: The Standardized Electrode Nomenclature for SEEG Application system was prospectively implemented in 40 consecutive patients undergoing SEEG monitoring at our institution, creating unique electrode names in all cases, and facilitating implantation design, SEEG recording and mapping interpretation, and treatment planning among neurosurgeons, neurologists, and neurophysiologists. The inter-rater percent agreement for electrode names among two neurosurgeons, two epilepsy neurologists, and one neurosurgical fellow was 97.5%. CONCLUSIONS: This standardized naming convention, Standardized Electrode Nomenclature for SEEG Application, provides a simple, concise, reproducible, and informative method for specifying the target(s) and relative position of each SEEG electrode in each patient, allowing for successful sharing of information in both the clinical and research settings. General adoption of this nomenclature could pave the way for improved communication and collaboration between institutions.

Early childhood epilepsies: epidemiology, classification, aetiology, and socio-economic determinants.

Epilepsies of early childhood are frequently resistant to therapy and often associated with cognitive and behavioural comorbidity. Aetiology focused precision medicine, notably gene-based therapies, may prevent seizures and comorbidities. Epidemiological data utilizing modern diagnostic techniques including whole genome sequencing and neuroimaging can inform diagnostic strategies and therapeutic trials. We present a 3-year, multicentre prospective cohort study, involving all children under 3 years of age in Scotland presenting with epilepsies. We used two independent sources for case identification: clinical reporting and EEG record review. Capture-recapture methodology was then used to improve the accuracy of incidence estimates. Socio-demographic and clinical details were obtained at presentation, and 24 months later. Children were extensively investigated for aetiology. Whole genome sequencing was offered for all patients with drug-resistant epilepsy for whom no aetiology could yet be identified. Multivariate logistic regression modelling was used to determine associations between clinical features, aetiology, and outcome. Three hundred and ninety children were recruited over 3 years. The adjusted incidence of epilepsies presenting in the first 3 years of life was 239 per 100 000 live births [95% confidence interval (CI) 216-263]. There was a socio-economic gradient to incidence, with a significantly higher incidence in the most deprived quintile (301 per 100 000 live births, 95% CI 251-357) compared with the least deprived quintile (182 per 100 000 live births, 95% CI 139-233), χ2 odds ratio = 1.7 (95% CI 1.3-2.2). The relationship between deprivation and incidence was only observed in the group without identified aetiology, suggesting that populations living in higher deprivation areas have greater multifactorial risk for epilepsy. Aetiology was determined in 54% of children, and epilepsy syndrome was classified in 54%. Thirty-one per cent had an identified genetic cause for their epilepsy. We present novel data on the aetiological spectrum of the most commonly presenting epilepsies of early childhood. Twenty-four months after presentation, 36% of children had drug-resistant epilepsy (DRE), and 49% had global developmental delay (GDD). Identification of an aetiology was the strongest determinant of both DRE and GDD. Aetiology was determined in 82% of those with DRE, and 75% of those with GDD. In young children with epilepsy, genetic testing should be prioritized as it has the highest yield of any investigation and is most likely to inform precision therapy and prognosis. Epilepsies in early childhood are 30% more common than previously reported. Epilepsies of undetermined aetiology present more frequently in deprived communities. This likely reflects increased multifactorial risk within these populations.

Proposal to optimize evaluation and treatment of Febrile infection-related epilepsy syndrome (FIRES): A Report from FIRES workshop.

Febrile infection-related epilepsy syndrome (FIRES) is a rare catastrophic epileptic encephalopathy that presents suddenly in otherwise normal children and young adults causing significant neurological disability, chronic epilepsy, and high rates of mortality. To suggest a therapy protocol to improve outcome of FIRES, workshops were held in conjunction with American Epilepsy Society annual meeting between 2017 and 2019. An international group of pediatric epileptologists, pediatric neurointensivists, rheumatologists and basic scientists with interest and expertise in FIRES convened to propose an algorithm for a standardized approach to the diagnosis and treatment of FIRES. The broad differential for refractory status epilepticus (RSE) should include FIRES, to allow empiric therapies to be started early in the clinical course. FIRES should be considered in all previously healthy patients older than two years of age who present with explosive onset of seizures rapidly progressing to RSE, following a febrile illness in the preceding two weeks. Once FIRES is suspected, early administrations of ketogenic diet and anakinra (the IL-1 receptor antagonist that blocks biologic activity of IL-1ß) are recommended.

Risk factors for drug-resistant epilepsy: A systematic review and meta-analysis.

BACKGROUND: Drug resistant epilepsy (DRE) is very common among children and adults and studies had found some related risk factors for DRE, while the results were not consistent. The aim of this study was to identify risk factors for drug-resistant epilepsy. METHODS: Three electronic databases (Medline, Embase and Cochrane library) were searched to identify studies with a cohort design reporting on epidemiologic evidence regarding risk factors for DRE. RESULTS: The pooled prevalence of DRE in newly diagnosed epilepsy patients was 25% (95% CI 17-32%). Abnormal electroencephalography (EEG) (both slow wave and epileptiform discharges) (RR 2.80; 95% CI 1.95-4.0), status epilepticus (SE) (RR 11.60; 95% CI 7.39-18.22), symptomatic etiology (RR 3.36; 95% CI 2.53-4.46), multiple seizure types (RR 3.66; 95% CI 2.37-5.64) and febrile seizures (RR 3.43; 95% CI 1.95-6.02) were identified as strong risk factors for DRE. In addition, firm conclusions cannot be drawn for poor short-term outcomes of therapy, neurodevelopment delay and high initial seizure frequency for the heterogeneity of study results. The predictive effect of focus onset seizure was not stable after removing one study and switching the effect model. Age of onset was not risk factors for DRE. CONCLUSIONS: The current meta-analysis identified potential risk factors for DRE. The results may contribute to better prevention strategies and treatments for DRE.

Drug-resistant epilepsy classified by a phenotyping algorithm associates with NTRK2.

OBJECTIVE: Up to 40% of patients with epilepsy become drug resistant (DRE). Genetic factors are likely to play a role. While efforts have focused on the transporter and target hypotheses, neither of them fully explains the pan-pharmacoresistance seen in DRE. MATERIALS AND METHODS: In this study, we developed and used a phenotyping algorithm for the identification of DRE, responders, and epilepsy-free controls that were sequenced using a gene panel developed by the Pharmacogenomics Research Network (PGRN), which includes 82 genes involved in drug response. We tested the transporter hypothesis of DRE, the association between drug resistance and variants in the ATP-binding cassette family of genes previously associated with DRE, and also investigated potential new genetic factors. RESULTS: In the analysis of DRE vs controls, NTRK2 was significantly associated with DRE (rs76950094; P = 1.19 × 10-7 and gene-based P-value = 1.67 × 10-4 ). NTRK2 encodes TrkB, which is involved in the development and maturation of the central nervous system, and increased activation of TrkB signaling is suggested to promote epilepsy. CONCLUSION: Although the role of NTRK2 in DRE needs to be elucidated, these results support alternative mechanisms underlying DRE, complementary to the existing hypotheses, that should be evaluated.

Are high-frequency oscillations better biomarkers of the epileptogenic zone than spikes?

PURPOSE OF REVIEW: Precise localization of the epileptogenic zone is imperative for the success of resective surgery of drug-resistant epileptic patients. To decrease the number of surgical failures, clinical research has been focusing on finding new biomarkers. For the past decades, high-frequency oscillations (HFOs, 80-500 Hz) have ousted interictal spikes - the classical interictal marker - from the research spotlight. Many studies have claimed that HFOs were more linked to epileptogenicity than spikes. This present review aims at refining this statement in light of recent studies. RECENT FINDINGS: Analysis based on single-patient characteristics has not been able to determine which of HFOs or spikes were better marker of epileptogenic tissues. Physiological HFOs are one of the main obstacles to translate HFOs to clinical practice as separating them from pathological HFOs remains a challenge. Fast ripples (a subgroup of HFOs, 250-500 Hz) which are mostly pathological are not found in all epileptogenic tissues. SUMMARY: Quantified measures of HFOs and spikes give complementary results, but many barriers still persist in applying them in clinical routine. The current way of testing HFO and spike detectors and their performance in delineating the epileptogenic zone is debatable and still lacks practicality. Solutions to handle physiological HFOs have been proposed but are still at a preliminary stage.

Generalized polyspike train: An EEG biomarker of drug-resistant idiopathic generalized epilepsy.

OBJECTIVE: To identify clinical and EEG biomarkers of drug resistance in adults with idiopathic generalized epilepsy. METHODS: We conducted a case-control study consisting of a discovery cohort and a replication cohort independently assessed at 2 different centers. In each center, patients with the idiopathic generalized epilepsy phenotype and generalized spike-wave discharges on EEG were classified as drug-resistant or drug-responsive. EEG changes were classified into predefined patterns and compared between the 2 groups in the discovery cohort. Factors associated with drug resistance in multivariable analysis were tested in the replication cohort. RESULTS: The discovery cohort included 85 patients (29% drug-resistant and 71% drug-responsive). Their median age at assessment was 32 years and 50.6% were female. Multivariable analysis showed that higher number of seizure types ever experienced (3 vs 1: odds ratio [OR] = 31.1, 95% confidence interval [CI]: 4.5-214, p < 0.001; 3 vs 2: OR = 14.6, 95% CI: 2.3-93.1, p = 0.004) and generalized polyspike train (burst of generalized rhythmic spikes lasting less than 1 second) during sleep were associated with drug resistance (OR = 10.8, 95% CI: 2.4-49.4, p = 0.002). When these factors were tested in the replication cohort of 80 patients (27.5% drug-resistant and 72.5% drug-responsive; 71.3% female; median age 27.5 years), the proportion of patients with generalized polyspike train during sleep was also higher in the drug-resistant group (OR = 4.0, 95% CI: 1.35-11.8, p = 0.012). CONCLUSION: Generalized polyspike train during sleep may be an EEG biomarker for drug resistance in adults with idiopathic generalized epilepsy.

New-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES): State of the art and perspectives.

We report the proceedings of the First International new-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES) Symposium. To promote awareness of this condition and foster research efforts, we conveyed the First International new-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES) Symposium. The conference was supported by The NORSE Institute (http://www.norseinstitute.org). This article summarizes the discussions that were held during the Symposium and presents our strategy to unravel the cause of these disorders and to improve patient care. The standardized definitions for these disorders that have been developed, are required to improve communication and facilitate the development of multicenter registries and biobanks. A distinction between childhood- and adult-onset forms of the syndrome is not supported by strong scientific evidence and it is argued that both should be studied together. Although the pathophysiology remains elusive, nascent evidence suggests a role for a postinfectious cytokine-mediated mechanism, which should be further investigated. It also appears important to develop tools for their early recognition and prompt treatment. Recent evidence suggests that specific electroencephalography (EEG) features might be helpful. The optimal treatment options remain to be determined; immune therapies are usually disappointing, but the ketogenic diet has proved effective in uncontrolled trials. NORSE and FIRES represent a very delicate clinical situation with specific communication issues between physicians and with patients and families. Standardized consensus definitions and a multidisciplinary multicenter strategy will help research efforts and improve clinical care for patients with NORSE and FIRES.

Proposed consensus definitions for new-onset refractory status epilepticus (NORSE), febrile infection-related epilepsy syndrome (FIRES), and related conditions.

We convened an international group of experts to standardize definitions of New-Onset Refractory Status Epilepticus (NORSE), Febrile Infection-Related Epilepsy Syndrome (FIRES), and related conditions. This was done to enable improved communication for investigators, physicians, families, patients, and other caregivers. Consensus definitions were achieved via email messages, phone calls, an in-person consensus conference, and collaborative manuscript preparation. Panel members were from 8 countries and included adult and pediatric experts in epilepsy, electroencephalography (EEG), and neurocritical care. The proposed consensus definitions are as follows: NORSE is a clinical presentation, not a specific diagnosis, in a patient without active epilepsy or other preexisting relevant neurological disorder, with new onset of refractory status epilepticus without a clear acute or active structural, toxic or metabolic cause. FIRES is a subcategory of NORSE, applicable for all ages, that requires a prior febrile infection starting between 2 weeks and 24 hours prior to onset of refractory status epilepticus, with or without fever at onset of status epilepticus. Proposed consensus definitions are also provided for Infantile Hemiconvulsion-Hemiplegia and Epilepsy syndrome (IHHE) and for prolonged, refractory and super-refractory status epilepticus. This document has been endorsed by the Critical Care EEG Monitoring Research Consortium. We hope these consensus definitions will promote improved communication, permit multicenter research, and ultimately improve understanding and treatment of these conditions.

[Clinical and pathological definition of temporal medium epilepsy subtypes with hypocampic sclerosis]. / Definición clínico-patológica de los subtipos de epilepsia temporal medial con esclerosis del hipocampo.

BACKGROUND AND OBJECTIVE: Mesial temporal lobe epilepsy with hippocampal sclerosis is the most common cause of refractory epilepsy, and the most common indication for surgery. Although effective, surgery fails in up to 40% of patients. The objective of our study was to establish a correlation between the different histological subtypes of mesial temporal lobe epilepsy with hippocampal sclerosis and the prognosis, seizures control, side effects and anticonvulsivant drug withdrawal in patients with refractory epilepsy. PATIENTS AND METHOD: Clinical histories and anatomopathological specimens of 228 patients with temporal epilepsy surgically obtained at our hospital between 1993 and 2014 were retrospectively analysed. All patients underwent a standard preoperative evaluation and anterior temporal resection (modified from Spencer). The anatomopathological study included the standard hematoxylin-eosin and immunohistochemical protocol, with special interest in the assessment of neuronal loss with NeuN. Seizure control was assessed according to the scale of results of the ILAE and Engel. The mean follow-up was 8.6 years (2-19). RESULTS: At 10 years after the intervention, 67.9% of patients were seizure-free (ILAE 1) and as many as 77.5% of the patients were seizure-free (Engel 1) at the end of the follow-up. The probability of not having a seizure (ILAE 1) after surgery at 2 (p=.042), 5 (p=.001) and 7 years (p=.22) was higher in classic and severe forms compared to isolated sclerosis CA1 and CA4 forms. Higher neuronal loss measured with the NeuN immunostain in CA1 was associated with better outcome in seizure management (multivariate analysis, p=.08). The presence of a personal history of epilepsy was associated with greater neuronal loss in CA1 (p=.028) and CA3 (p=.034), and the presence of psychic auras was related with greater neuronal loss in CA3 (p=.025). In our case, the probability of medication withdrawal was related to the presence of personal history (p=.003) and, inversely, to neuronal loss in CA1 (p=.036) and CA3 (p=.038). The greatest impairment of verbal memory occurred in those patients with a lower neuronal loss in CA1 (p=.023), CA2 (p=.049) and CA3 (p=.035). CONCLUSIONS: The results indicate that the classical and severe subtypes have a better prognosis in the control of seizures against the atypical forms, validating the clinical and prognostic utility of the classification of histological subtypes of hippocampal sclerosis from the ILAE. The value of the immunohistochemistry in the mesial temporal lobe epilepsy with hippocampal sclerosis has been demonstrated as a key element to determine the neuropsychological prognosis and seizure management of the patients after surgery.

[Neuropathologic findings in intractable epilepsy: a clinicopathologic analysis of 822 cases].

Objective: To investigate the clinicopathologic characteristics of intractable epilepsy. Methods: Based on the classification criteria proposed by the International League Against Epilepsy (ILAE), a retrospective analysis of the pathological characteristics was done in 822 patients who underwent epilepsy surgery in Sanbo Brain Hospital, Capital Medical University, from June 2008 to December 2012. Results: The mean age of epilepsy onset was 9.9 years, mean duration of epilepsy was 11.9 years. Complex partial seizures were the main presenting features. Histopathological study showed 33 cases (4.01%) with mild forms of cortical malformations, 690 cases (83.94%) with focal cortical dysplasia (FCD) and 99 cases with others (including 39 pure hippocampal sclerosis, 20 cystosclerosis, 19 Sturge-Weber syndrome, 8 tuberous sclerosis complex, 6 without significant pathological changes, 5 gyral malformations and 2 hamartoma). Among the 690 FCD cases, 106 were FCD typeⅠ, 91 were FCD typeⅡ and 493 were FCDⅢ(Ⅲa: 160, Ⅲb: 106, Ⅲc: 26 and Ⅲd: 201). Conclusions: FCDⅢd is the most common histopathological subtype causing intractable epilepsy, mainly due to focal hypoxia/ischemia in the perinatal period, which results in scarring of local brain tissue; this is followed by other isolated forms of FCD (FCDⅠand FCDⅡ), and then FCD Ⅲa and FCD Ⅲb. The reason to distinguish isolated forms of FCD (types Ⅰ and Ⅱ) from FCD Ⅲ and to subclassify FCD Ⅲ is to allow better definition of cortical dyslamination. Therefore, the pathogenic factors of intractable epilepsy can be grouped in greater details, and facilitate the diagnosis and potential curative treatment of intractable epilepsy.

Derivation and initial validation of a surgical grading scale for the preliminary evaluation of adult patients with drug-resistant focal epilepsy.

OBJECTIVE: Presently, there is no simple method at initial presentation for identifying a patient's likelihood of progressing to surgery and a favorable outcome. The Epilepsy Surgery Grading Scale (ESGS) is a three-tier empirically derived mathematical scale with five categories: magnetic resonance imaging (MRI), electroencephalography (EEG), concordance (between MRI and EEG), semiology, and IQ designed to stratify patients with drug-resistant focal epilepsy based on their likelihood of proceeding to resective epilepsy surgery and achieving seizure freedom. METHODS: In this cross-sectional study, we abstracted data from the charts of all patients admitted to the New York University Langone Medical Center (NYULMC) for presurgical evaluation or presented in surgical multidisciplinary conference (MDC) at the NYU Comprehensive Epilepsy Center (CEC) from 1/1/2007 to 7/31/2008 with focal epilepsy, who met minimal criteria for treatment resistance. We classified patients into ESGS Grade 1 (most favorable), Grade 2 (intermediate), and Grade 3 (least favorable candidates). Three cohorts were evaluated: all patients, patients presented in MDC, and patients who had resective surgery. The primary outcome measure was proceeding to surgery and seizure freedom. RESULTS: Four hundred seven patients met eligibility criteria; 200 (49.1%) were presented in MDC and 113 (27.8%) underwent surgery. A significant difference was observed between Grades 1 and 3, Grades 1 and 2, and Grades 2 and 3 for all presurgical patients, and those presented in MDC, with Grade 1 patients having the highest likelihood of both having surgery and becoming seizure-free. There was no difference between Grades 1 and 2 among patients who had resective surgery. SIGNIFICANCE: These results demonstrate that by systematically using basic information available during initial assessment, patients with drug-resistant epilepsy may be successfully stratified into clinically meaningful groups with varied prognosis. The ESGS may improve communication, facilitate decision making and early referral to a CEC, and allow patients and physicians to better manage expectations.

Seizure-specific wavelet (Seizlet) design for epileptic seizure detection using CorrEntropy ellipse features based on seizure modulus maximas patterns.

BACKGROUND: EEG signal analysis of pediatric patients plays vital role for making a decision to intervene in presurgical stages. NEW METHOD: In this paper, an offline seizure detection algorithm based on definition of a seizure-specific wavelet (Seizlet) is presented. After designing the Seizlet, by forming cone of influence map of the EEG signal, four types of layouts are analytically designed that are called Seizure Modulus Maximas Patterns (SMMP). By mapping CorrEntropy Induced Metric (CIM) series, four structural features based on least square estimation of fitted non-tilt conic ellipse are extracted that are called CorrEntropy Ellipse Features (CEF). The parameters of the SMMP and CEF are tuned by employing a hybrid optimization algorithm based on honeybee hive optimization in combination with Las Vegas randomized algorithm and Elman recurrent classifier. Eventually, the optimal features by AdaBoost classifiers in a cascade structure are classified into the seizure and non-seizure signals. RESULTS: The proposed algorithm is evaluated on 844h signals with 163 seizure events recorded from 23 patients with intractable seizure disorder and accuracy rate of 91.44% and false detection rate of 0.014 per hour are obtained by 7-channel EEG signals. COMPARISON WITH EXISTING METHOD(S): To overcome the restrictions of general kernels and wavelet coefficient-based features, we designed the Seizlet as an exclusive kernel of seizure signal for first time. Also, the Seizlet-based patterns of EEG signals have been modeled to extract the seizure. CONCLUSIONS: The reported results demonstrate that our proposed Seizlet is effectiveness to extract the patterns of the epileptic seizure.

Clinical and electrophysiological findings in mesial temporal lobe epilepsy with hippocampal sclerosis, based on the recent histopathological classifications.

BACKGROUND: Hippocampal sclerosis (HS) is a common pathology in MTLE, patients may show different surgical outcomes and clinical features. The 2013 ILAE classification subdivides HS into 3 types (HS type 1: severe neuronal loss and gliosis predominantly in CA1 and CA4 regions; - HS type 2: CA1 predominant; HS type 3: CA4 predominant) and includes "gliosis only, as no-HS". The association of clinical and electrophysiological findings with different HS types has not been reported previously in detail. METHODS: 48 patients who had undergone temporal lobectomy with amygdalohippocampectomy due to mesial TLE-HS between February 2014 and February 2016 were included. The patients were divided into five groups: patients with HS ILAE type 1, HS ILAE type 2, HS ILAE type 3, FCD type IIIa, or gliosis/no HS. The correlation between HS ILAE types and clinical/EEG findings in patients with MTLE due to HS was investigated. RESULTS: Of the 48 patients 30 were male. In 23 patients, the resection was on the left side (48%). Three patients had only gliosis, 25 patients had HS ILAE type 1, 7 had HS ILAE type 2, and 4 had HS ILAE type 3. Nine of the 48 patients had cortical lamination abnormalities in the temporal lobe associated with HS (FCD type IIIa). All patients were seizure free for early follow up. There was no association between type of HS in terms of duration of epilepsy, onset age of epilepsy, lateralized or localized semiological findings, or interictal/ictal EEG findings. Family history of epilepsy or SGTCSs were statistically more frequent in patients with types 2 and 3 HS and status epilepticus was more frequent in patients with HS-FCD type IIIa. CONCLUSION: The patients with HS types 2 and 3 have more frequent SGTCS or status epilepticus as well as increased family history of epilepsy. These findings can be helpful in understanding the epileptogenicity-prognoses of HS.

Pathology-Based Approach to Seizure Outcome After Surgery for Pharmacoresistant Medial Temporal Lobe Epilepsy.

BACKGROUND: Hippocampal sclerosis (HS) is the most common cause of drug-resistant medial temporal lobe epilepsy (MTLE). Structural abnormalities such as HS, granule cell pathology (GCP), and focal cortical dysplasia (FCD) have been classified histopathologically, possibly allowing a more accurate assessment of prognostic seizure and neuropsychologic outcomes. We correlated seizure outcome with comprehensive temporal lobe pathologic findings, identified according to the most recent classification systems of HS, GCP, and FCD. METHODS: All the 83 patients who underwent anterior temporal lobectomy (ATL) for drug-resistant MTLE and with a proven diagnosis of HS between April 2001 and May 2014 were collected. Patients were divided in 2 main groups: 1) isolated HS with/without GCP (HS +/- GCP); and 2) HS associated with FCD with/without GCP (HS+FCD +/- GCP). Patients were followed up at least 1 year, and seizure outcome was reported in accordance with Engel classification. RESULTS: Group I: HS +/- GCP: Statistical analysis confirmed a better outcome in HS + GCP patients than in HS-no GCP (P < 0.05). Moreover, a better outcome for the patients affected by GCP type I was observed (P < 0.05). Group II: HS+FCD +/- GCP: Patients with HS variant type I presented a better seizure outcome than the patients with HS type II (Engel class IA HS type I vs. type II: 69% vs. 40%). CONCLUSIONS: A pathology-based approach to epilepsy surgery might improve the interpretation of the results, could predict which cases will enjoy a better seizure outcome, and could help to the comprehension of the causes of failures.

Clinical predictors of 2-year outcome of resective epilepsy surgery in adults with refractory epilepsy: a cohort study.

OBJECTIVES: Resective epilepsy surgery is currently a standard treatment for intractable epilepsy. Seizure freedom and discontinuation of antiepileptic drugs are the ultimate goals of epilepsy treatment. This study was carried out to delineate (1) possible differences in the success rate of epilepsy surgery 6 and 24 months after surgery; and (2) the clinical predictors of a good response to surgery. SETTING: This is a cohort study performed at a tertiary care unit of a university hospital. PARTICIPANTS: In this cohort study, 189 adults with intractable epilepsy who underwent epilepsy surgery were included. We collected clinical data at three time points, that is, preoperative and 6 and 24 months after surgery. PRIMARY AND SECONDARY OUTCOME MEASURES: Engel class I-IV classification was the primary outcome measure of epilepsy surgery. The authors statistically adjusted Engel class I-IV classification for postoperative changes in antiepileptic drugs and used this new classification as a secondary outcome variable. RESULTS: The success rate was 78.8% 6 months after surgery and increased to 88.3% 24 months after surgery. This success rate was reflected not only by the reduced number of seizures postsurgery, but also by a reduced dosage and use of antiepileptic drugs. Logistic regression analysis showed that a successful outcome of surgery is predicted by having temporal rather than extratemporal lobe epilepsy and less than nine presurgery seizures per month, while a positive familial history of epilepsy, younger age and dysphoric symptoms, the first 3 months after surgery, significantly worsened the outcome of surgery. Duration of illness, age at onset, epilepsy location, type of lesions and the presence of psychosis were not significant in predicting treatment outcome. CONCLUSIONS: These findings have clinical relevance in that a better selection of patients based on the significant clinical predictors will increase the success rate of epilepsy surgery and treatment.