Seizure Focus In Patients Research Articles

Validation of the rapid and simple LC-MS/MS method for the quantification of pregabalin in plasma of acutely poisoned patients

AbstractPregabalin is a gabapentinoid approved for the treatment of general anxiety disorder, neuropathic pain and as adjunctive therapy for focal seizures in patients with epilepsy. In addition, there are a number of conditions for which pregabalin is prescribed off-label. Along with the widespread use there are a significant number of reports describing the misuse of pregabalin over the last decade. Over time, it became clear that pregabalin should become part of routine testing in toxicology laboratories. The aim of this paper was to present validation of a LC-MS/MS method for the quantification of pregabalin in plasma of acutely poisoned patients. Simple sample preparation step and rapid chromatographic separation shortened the overall analysis time, which was the goal of method development. The presence of pregabalin was confirmed with three ion transitions, ensuring high selectivity of the validated method. The statistical data obtained showed good precision and accuracy over a wide concentration range. No endogenous or other interference was detected, and there was no matrix effect influence with this method. The LC-MS/MS method was applied to quantify pregabalin in plasma samples of patients admitted to the emergency department due to a possible acute pregabalin overdose. Different concentrations were found, and we report, to the best of our knowledge, the highest plasma concentration of pregabalin in the plasma of a patient with acute poisoning. In conclusion, we developed a fast and simple LC-MS/MS method for reliable determination of pregabalin and demonstrated the developed method was suitable for routine use in clinical toxicology setting.

Long-term Cenobamate for Uncontrolled Focal Seizures in Patients Living in a Group Home or With Developmental Disability (P4-1.006)

Long-term Cenobamate for Uncontrolled Focal Seizures in Patients Living in a Group Home or With Developmental Disability (P4-1.006)

The Association Between Alzheimer's Disease and Epilepsy: A Narrative Review.

Several studies have established the two-way relationship between the sporadic and familial forms of Alzheimer's disease (AD) and epilepsy. However, a more robust connection exists between epilepsy and early onset familial AD (EOFAD). Still, the mechanisms underlying the same are not yet fully understood. Aging is also known to be associated with both AD and seizures. Seizures of any type can occur at any stage of AD and are six to 10 times more likely in patients with AD than in controls of a similar age group. Seizures can quicken cognitive decline and increase mortality, amplifying the medical and economic burden. It is, therefore, clinically essential to recognize and treat seizures early in these patients. However, diagnosis of seizures in AD is complicated by the difficulty in identifying non-motor focal seizures in patients with cognitive decline, problems with obtaining histories, low sensitivity of standard scalp electroencephalogram (EEG) methods, nonspecific cerebrospinal fluid (CSF) and radiological findings. This article has reviewed and summarised the existing literature on the association between AD and epilepsy pertaining to epidemiology, pathophysiological links, risk factors, modalities for diagnosis, and treatment strategies.

Seizure semiology: ILAE glossary of terms and their significance.

This educational topical review and Task Force report aims to address learning objectives of the International League Against Epilepsy (ILAE) curriculum. We sought to extract detailed features involving semiology from video recordings and interpret semiological signs and symptoms that reflect the likely localization for focal seizures in patients with epilepsy. This glossary was developed by a working group of the ILAE Commission on Diagnostic Methods incorporating the EEG Task Force. This paper identifies commonly used terms to describe seizure semiology, provides definitions, signs and symptoms, and summarizes their clinical value in localizing and lateralizing focal seizures based on consensus in the published literature. Video-EEG examples are included to illustrate important features of semiology in patients with epilepsy.

Efficacy of cenobamate for uncontrolled focal seizures in patients with previous epilepsy-related surgery: Post hoc analysis of a phase 3, multicenter, open-label study

ObjectiveThis post hoc analysis of 10 US study sites from a long-term open-label phase 3 study of adjunctive cenobamate evaluated the efficacy of cenobamate in patients with prior epilepsy-related surgery. MethodsPatients with uncontrolled focal seizures despite taking stable doses of 1–3 concomitant antiseizure medications (ASMs) received increasing doses of cenobamate (12.5, 25, 50, 100, 150, 200 mg/day) at 2-week intervals over 12 weeks (target dose, 200 mg/day). Further increases up to 400 mg/day using biweekly 50-mg/day increments were allowed during the maintenance phase. Dose adjustments of cenobamate and concomitant ASMs were allowed. Data were assessed until the last clinic visit on or after September 1, 2019. ResultsOf the 240 eligible patients, 85 had prior epilepsy-related surgery and 155 were nonsurgical patients. Baseline focal seizure frequency per 28 days was numerically higher among prior surgery (mean=25.9/median=4.1/range=0.3–562.3) versus nonsurgical (mean=13.8/median=2.4/range=0.2–534.2) patients. Among all patients, 100 % seizure reduction ≥ 12 months at any consecutive month interval occurred in 30.6 % (26/85) prior surgery and 39.4 % (61/155; p > 0.05) nonsurgical patients (cenobamate treatment median duration=32.9 months). Among the 177 patients still receiving cenobamate at the data cutoff, 29.2 % (19/65) of prior surgery and 36.6 % (41/112; p > 0.05) of nonsurgical patients had 100 % seizure reduction ≥ 12 months at the data cutoff. Cenobamate was well tolerated. ConclusionsThis post hoc analysis supports the efficacy of cenobamate in patients with refractory focal seizures despite prior surgery. These findings suggest cenobamate may be considered early in the treatment regimen, including, in some patients, before surgery is considered.

Cenobamate for Uncontrolled Focal Seizures in Patients With Previous Epilepsy-Related Surgery: A Post-hoc Analysis (P13-8.003)

Cenobamate for Uncontrolled Focal Seizures in Patients With Previous Epilepsy-Related Surgery: A Post-hoc Analysis (P13-8.003)

Cenobamate for Uncontrolled Focal Seizures in Patients Living in a Group Home or With a Developmental Disability (P1-8.006)

Cenobamate for Uncontrolled Focal Seizures in Patients Living in a Group Home or With a Developmental Disability (P1-8.006)

Effectiveness and tolerability of perampanel in сhildren and adolescents (own experience of Svt. Luka’s Institute of Child Neurology and Epilepsy)

Effectiveness and tolerability of perampanel in сhildren and adolescents (own experience of Svt. Luka’s Institute of Child Neurology and Epilepsy)

LeGUI: A Fast and Accurate Graphical User Interface for Automated Detection and Anatomical Localization of Intracranial Electrodes.

Accurate anatomical localization of intracranial electrodes is important for identifying the seizure foci in patients with epilepsy and for interpreting effects from cognitive studies employing intracranial electroencephalography. Localization is typically performed by coregistering postimplant computed tomography (CT) with preoperative magnetic resonance imaging (MRI). Electrodes are then detected in the CT, and the corresponding brain region is identified using the MRI. Many existing software packages for electrode localization chain together separate preexisting programs or rely on command line instructions to perform the various localization steps, making them difficult to install and operate for a typical user. Further, many packages provide solutions for some, but not all, of the steps needed for confident localization. We have developed software, Locate electrodes Graphical User Interface (LeGUI), that consists of a single interface to perform all steps needed to localize both surface and depth/penetrating intracranial electrodes, including coregistration of the CT to MRI, normalization of the MRI to the Montreal Neurological Institute template, automated electrode detection for multiple types of electrodes, electrode spacing correction and projection to the brain surface, electrode labeling, and anatomical targeting. The software is written in MATLAB, core image processing is performed using the Statistical Parametric Mapping toolbox, and standalone executable binaries are available for Windows, Mac, and Linux platforms. LeGUI was tested and validated on 51 datasets from two universities. The total user and computational time required to process a single dataset was approximately 1 h. Automatic electrode detection correctly identified 4362 of 4695 surface and depth electrodes with only 71 false positives. Anatomical targeting was verified by comparing electrode locations from LeGUI to locations that were assigned by an experienced neuroanatomist. LeGUI showed a 94% match with the 482 neuroanatomist-assigned locations. LeGUI combines all the features needed for fast and accurate anatomical localization of intracranial electrodes into a single interface, making it a valuable tool for intracranial electrophysiology research.

Clinical and Economic Outcomes of Intravenous Brivaracetam Compared With Levetiracetam for the Treatment of Seizures in United States Hospitals.

Background: Seizures are common among hospitalized patients. Levetiracetam (LEV), a synaptic vesicle protein 2A (SV2A) ligand, is a common intravenous (IV) anti-seizure medication option in hospitals. Brivaracetam (BRV), a selective SV2A ligand for treatment of focal seizures in patients ≥16 years, has greater binding affinity, higher lipophilicity, and faster brain entry than IV LEV. Differences in clinical outcomes and associated costs between IV BRV and IV LEV in treating hospitalized patients with seizure remain unknown.Objectives: To compare the clinical outcomes, costs, and healthcare resource utilization between patients with seizure treated with IV BRV and those with IV LEV within hospital setting.Design/Methods: A retrospective cohort analysis was performed using chargemaster data from 210 United States hospitals in Premier Healthcare Database. Adult patients (age ≥18 years) treated intravenously with LEV or BRV (with or without BZD) and a seizure discharge diagnosis between July 1, 2016 and December 31, 2019 were included. The cohorts were propensity score-matched 4:1 on baseline characteristics. Outcomes included intubation rates, intensive care unit (ICU) admission, length of stay (LOS), all-cause and seizure-related readmission, total hospitalization cost, and in-hospital mortality. A multivariable regression analysis was performed to determine the association between treatment and main outcomes adjusting for unbalanced confounders.Results: A total of 450 patients were analyzed (IV LEV, n = 360 vs. IV BRV, n = 90). Patients treated with IV BRV had lower crude prevalence of ICU admission (14.4 vs. 24.2%, P < 0.05), 30-day all-cause readmission (1.1 vs. 6.4%, P = 0.06), seizure-related 30-day readmission (0 vs. 4.2%, P < 0.05), similar mean total hospitalization costs ($13,715 vs. $13,419, P = 0.91), intubation (0 vs. 1.1%, P = 0.59), and in-hospital mortality (4.4 vs. 3.9%, P = 0.77). The adjusted odds for ICU admission (adjusted odds ratio [aOR] = 0.6; 95% confidence interval [CI]:0.31, 1.16; P = 0.13), 30-day all-cause readmission (aOR = 0.17; 95% CI:0.02, 1.24; P = 0.08), and in-hospital mortality (aOR = 1.15; 95% CI:0.37, 3.58, P = 0.81) were statistically similar between comparison groups.Conclusion: The use of IV BRV may provide an alternative to IV LEV for management of seizures in hospital setting due to lower or comparable prevalence of ICU admission, intubation, and 30-day seizure-related readmission. Additional studies with greater statistical power are needed to confirm these findings.

Brivaracetam Retention Rate and Seizure Outcomes in Patients with Drug-Resistant Focal Epilepsy Included in the Medical Need Program in Belgium: A Real-World, Multicenter, Chart Review.

BackgroundNew treatments are needed for patients with drug-resistant epilepsy to improve seizure control without decreasing quality of life.ObjectiveIn Belgium, a Medical Need Program (MNP) was initiated to make a new antiepileptic drug (brivaracetam; high-affinity synaptic vesicle protein 2A ligand) available as adjunctive therapy to treat focal seizures in patients failing treatment with three or more different antiepileptic drugs. This is a real-world chart review of the majority of patients (71%) enrolled in the MNP.Patients and MethodsRetention and seizure outcomes of brivaracetam adjunctive treatment were evaluated in 175 patients aged ≥ 16 years enrolled in the MNP between June 2016 and May 2017 at six centers; 95.4% were previously/concomitantly treated with levetiracetam. Safety events data were also collected.ResultsIn this highly drug-resistant population, 85.8%, 73.9%, and 64.9% of patients remained on brivaracetam, while seizure frequency decreased from baseline in 32.0%, 37.1%, and 37.3% of patients after 3, 6, and 9 months’ treatment, respectively. Patients achieving 3-month seizure freedom increased from 3.2% after 3 months’ treatment to 10.2% and 10.7% after 6 and 9 months’ treatment, respectively. Six-month seizure freedom was achieved by 5.7% of patients at any time. Qualitative evaluation of seizures by physicians demonstrated 44.2%, 38.8%, and 43.2% of patients improved and 42.8%, 50.9%, and 50.6% remained unchanged during 3, 6, and 9 months’ follow-up, respectively. No safety signals were identified.ConclusionsRetention was high during 9 months of brivaracetam treatment in drug-resistant patients, including those previously/concomitantly treated with levetiracetam; 3-month seizure freedom increased from 3.2% after 3 months to 10.7% after 9 months of treatment.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40801-021-00246-7.

Seizure focus in the frontal interhemispheric fissure leads to ipsilateral isolated eye deviation

ObjectiveFew studies have examined the localization of seizures presenting with ictal eye deviation (ED) in the absence of other motor symptoms. We aimed to investigate differences in the localization of the ictal onset zone (IOZ) between patients with isolated ED and those with ED plus head turning (HT) during focal seizures. MethodsWe reviewed intracranial video-EEG data for 931 seizures in 80 patients with focal onset epilepsy in whom the IOZ could be confirmed. The 233 seizures in 49 patients with ED were classified into two semiological groups based on initial ED and the presence/absence of HT: (1) isolated ED (i.e., ED without HT), and (2) ED + HT (i.e., ED with HT). We analyzed the localization and lateralization of IOZs in each semiological group. We performed multivariate logistic regression analysis using a mixed-effects to determine the associations between IOZs and isolated ED/ED + HT. ResultsA total of 183 IOZs in 24 patients were included in the isolated ED group, while a total of 143 IOZs in 31 patients were included in the ED + HT group. Sixty-eight IOZs of eight patients in the isolated ED group were located in the ipsilateral frontal interhemispheric fissure (F-IHF). Only ipsilateral F-IHF was significantly associated with isolated ED (odds ratio [OR], 2.43; 95% confidence interval [CI], 0.37–4.49; P = 0.021). The contralateral lateral frontal cortex (latF) (P = 0.007) and ipsilateral mesial temporal region (mT) (P = 0.029) were significantly associated with ED + HT. ConclusionThe present study is the first to demonstrate that seizures with an F-IHF focus tend to present with initial ipsilateral isolated ED. This finding may aid in identifying the seizure focus in patients with isolated ED prior to resection.

An electric-field-responsive paramagnetic contrast agent enhances the visualization of epileptic foci in mouse models of drug-resistant epilepsy

For patients with drug-resistant focal epilepsy, excision of the epileptogenic zone is the most effective treatment approach. However, the surgery is less effective in the 15-30% of patients whose lesions are not distinct when visualized by magnetic resonance imaging (MRI). Here, we show that an intravenously administered MRI contrast agent consisting of a paramagnetic polymer coating encapsulating a superparamagnetic cluster of ultrasmall superparamagnetic iron oxide crosses the blood-brain barrier and improves lesion visualization with high sensitivity and target-to-background ratio. In kainic-acid-induced mouse models of drug-resistant focal epilepsy, electric-field changes in the brain associated with seizures trigger breakdown of the contrast agent, restoring the T1-weighted magnetic resonance signal, which otherwise remains quenched due to the distance-dependent magnetic resonance tuning effect between the cluster and the coating. The electric-field-responsive contrast agent may increase the probability of detecting seizure foci in patients and facilitate the study of brain diseases associated with epilepsy.

Diagnostic yield of seizure recordings and neuroimaging in patients with focal epilepsy without interictal epileptiform discharges

ObjectiveRepeated routine electroencephalography (EEG) or even long-term video-EEG monitoring (VEM) does not always record interictal epileptiform discharges (IEDs) in some patients with epilepsy. The present study investigated whether focal seizures detected by VEM and focal abnormalities on neuroimaging are useful for the diagnosis of patients with focal epilepsy without IEDs. MethodsWe retrospectively reviewed 409 consecutive patients with focal epilepsy (207 men, aged 9 to 76 years) who underwent 4- or 5-day VEM, magnetic resonance imaging (MRI), and fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) for diagnosis to identify patients without IEDs. The occurrence of focal seizures during VEM and the presence of focal abnormalities on neuroimaging were investigated in those patients. The occurrence rate of seizures during VEM was investigated in patients with daily, weekly, monthly, and yearly seizure frequency based on history-taking. ResultsNinety-five (23.2%) of 409 patients with focal epilepsy did not have IEDs. Fifty-five (57.9%) of the 95 patients had focal seizures during VEM. Fifty-four patients (56.8%) showed focal abnormalities compatible with seizure semiology on neuroimaging investigations. Neither seizure recordings nor neuroimaging abnormalities were seen in 16 (16.8%) of the 95 patients. The occurrence rate of seizures during VEM depended on the seizure frequency at history-taking. However, 28 (45.9%) of 61 patients with monthly and yearly seizure frequency had focal seizures during 4- or 5-day VEM with seizure induction. ConclusionsVideo-EEG monitoring can detect focal seizures in patients with focal epilepsy but no IEDs. Comprehensive assessment including VEM and neuroimaging study is important for the diagnosis.

Safety and tolerability of adjunctive brivaracetam in epilepsy: In-depth pooled analysis

ObjectiveThe objective of this analysis was to provide a comprehensive analysis of safety data for adjunctive brivaracetam (BRV), an antiepileptic drug (AED) of the racetam class, for treatment of focal seizures in patients with epilepsy. MethodsData were pooled from two phase II, placebo-controlled, double-blind, dose-ranging trials (N01114 [ClinicalTrials.gov: NCT00175929], N01193 [NCT00175825]) and three phase III, placebo-controlled, double-blind, 12-week trials (N01252 [NCT00490035], N01253 [NCT00464269], and N01358 [NCT01261325]) in patients aged ≥16 years with focal seizures, as well as a phase III, placebo-controlled, double-blind, 16-week trial in patients aged ≥16 years with focal or generalized epilepsy (N01254 [NCT00504881]). Data are presented for the approved therapeutic dose range of 50–200 mg/day. Data for BRV administered intravenously (25–150 mg doses) were pooled separately from one phase III trial (N01258 NCT01405508]) and two clinical pharmacology trials (N01256 [Part B] [UCB Pharma, data on file]; EP0007 [NCT01796899]). Adverse events (AEs) of interest were summarized in relevant categories. ResultsThe safety pool comprised 1957 patients: 1271 receiving adjunctive BRV and 686 receiving placebo. Overall, the incidence of treatment-emergent adverse events (TEAEs) was 66.9% with BRV versus 62.8% with placebo. The most frequently reported TEAEs with BRV (≥5% of patients) versus placebo were somnolence (13.3% vs. 7.9%), headache (10.5% vs. 11.5%), dizziness (10.0% vs. 7.0%), and fatigue (8.2% vs. 4.2%). Incidence of psychiatric disorder-related TEAEs was 11.3% with BRV versus 8.2% with placebo. Behavioral disorder-related TEAE incidence was low (4.0% with BRV vs. 2.5% with placebo). Irritability was reported in 2.7% of BRV-treated patients vs. 1.5% of patients receiving placebo; anger, aggression, and agitation were each reported by ≤1% of patients receiving BRV. Treatment-emergent adverse events potentially associated with psychosis were psychotic disorder (three patients on BRV vs. two patients on placebo), auditory hallucination, illusion, visual hallucination (one patient each on BRV), epileptic psychosis, and hallucination (one patient each on placebo). No additional safety concerns were identified in patients with intravenous (IV) BRV administration (n = 104). ConclusionsThese safety data for adjunctive BRV support its acceptable safety and tolerability profile.

Investigating the safety of fast neural electrical impedance tomography in the rat brain

Objective: Electrical impedance tomography (EIT) can be used to image impedance changes which arise due to fast electrical activity during neuronal depolarisation and so holds therapeutic potential for improving the localisation of epileptic seizure foci in patients with treatment-resistant epilepsy to aid surgical resection of epileptogenic tissue. Prolonged cortical stimulation may, however, induce neural injury through excitotoxicity and electrochemical reactions at the tissue–electrode interface. The purpose of this work was to assess whether current levels used in fast neural EIT studies induce histologically detectable tissue damage when applied continuously to the rat cerebral cortex. Approach: A 57-electrode epicortical array was placed on one or both hemispheres of adult Sprague Dawley rats anaesthetised with isoflurane. In an initial series of experiments, current was injected simultaneously at 10, 25, 50, 75 and 100 µA for 1 h at 1.725 kHz through five electrodes across two epicortical arrays to provide a preliminary indication of the safety of these current levels. Since no obvious cortical damage was observed in these rats, the current level chosen for further investigation was 100 µA, the upper-bound of the range of interest. In a separate series of experiments, 100 µA was applied through a single electrode for 1 h at 1.725 kHz to verify its safety. Following termination of stimulation, brain samples were fixed in formalin and histologically processed with Haematoxylin and Eosin (H&E) and Nissl stains. Main results: Histological analysis revealed that continuous injection of 100 µA current, equating to a current density of 354 Am−2, into the rat cortex at 1.725 kHz does not cause cortical tissue damage or any alterations to neuronal morphology. Significance: The safety of current injections during typical EIT protocols for imaging fast neural activity have been validated. The current density established to be safe for continuous application to the cortex, 354 Am−2, exceeds the present safety limit of 250 Am−2 which has been complied with to date, and thus encourages the application of more intensified fast neural EIT protocols. These findings will aid protocol design for future clinical and in vivo EIT investigations aimed at imaging fast neural activity, particularly in situations where the signal-to-noise ratio is considerably reduced.

Diagnostic usefulness of arterial spin labeling in MR negative children with new onset seizures

PurposeArterial spine labeling (ASL) magnetic resonance imaging (MRI) is the non-invasive measurement of cerebral blood flow that can localize the seizure focus in patients with epilepsy. The aim of this study was to identify its utility for localizing the seizure focus in children with no structural lesion on MRI. MethodsForty-three consecutive children who underwent electroencephalography (EEG) and structural MRI, along with ASL for evaluation of newly developed seizures, were included. ASL abnormalities were classified as hypo/hyperperfusion, based on visual assessment, and compared with the seizure focus determined by clinical information and EEG. ResultsAmong the 43 patients (M 17: F 26, mean age, 6.3 ± 3.3 years), the seizure type was focal in 36 patients and generalized in seven patients. Twenty-five (58.1%) patients showed perfusion change. Out of 36 patients with focal seizure, 24 (66.7%) showed ASL abnormalities, and 19 (52.8%) showed concordance between ASL and clinical focus. Out of seven patients with generalized seizure, only one patient showed ASL abnormalities. The overall concordance revealed moderate agreement (k = 0.542). ASL acquisition within one day from seizure onset was the only significant associating factor with the concordance between the two (p = 0. 014). ConclusionTo our knowledge, this is the first study to assess the usefulness of ASL MRI to assist in localizing the seizure focus in MR-negative children with new onset seizures. The combined use of ASL with EEG and structural MRI may play an important role in the evaluation of pediatric epilepsy.

Clinical Value of Hybrid TOF-PET/MR Imaging-Based Multiparametric Imaging in Localizing Seizure Focus in Patients with MRI-Negative Temporal Lobe Epilepsy.

Temporal lobe epilepsy is the most common type of epilepsy. Early surgical treatment is superior to prolonged medical therapy in refractory temporal lobe epilepsy. Successful surgical operations depend on the correct localization of the epileptogenic zone. This study aimed to evaluate the clinical value of hybrid TOF-PET/MR imaging-based multiparametric imaging in localizing the epileptogenic zone in patients with MR imaging-negative for temporal lobe epilepsy. Twenty patients with MR imaging-negative temporal lobe epilepsy who underwent preoperative evaluation and 10 healthy controls were scanned using PET/MR imaging with simultaneous acquisition of PET and arterial spin-labeling. On the basis of the standardized uptake value and cerebral blood flow, receiver operating characteristic analysis and a logistic regression model were used to evaluate the predictive value for the localization. Statistical analyses were performed using statistical parametric mapping. The values of the standardized uptake value and cerebral blood flow, as well as the asymmetries of metabolism and perfusion, were compared between the 2 groups. Histopathologic findings were used as the criterion standard. Complete concordance was noted in lateralization and localization among the PET, arterial spin-labeling, and histopathologic findings in 12/20 patients based on visual assessment. Concordance with histopathologic findings was also obtained for the remaining 8 patients based on the complementary PET and arterial spin-labeling information. Receiver operating characteristic analysis showed that the sensitivity and specificity of PET, arterial spin-labeling, and combined PET and arterial spin-labeling were 100% and 81.8%, 83.3% and 54.5%, and 100% and 90.9%, respectively. When we compared the metabolic abnormalities in patients with those in healthy controls, hypometabolism was detected in the middle temporal gyrus (P < .001). Metabolism and perfusion asymmetries were also located in the temporal lobe (P < .001). PET/MR imaging-based multiparametric imaging involving arterial spin-labeling may increase the clinical value of localizing the epileptogenic zone by providing concordant and complementary information in patients with MR imaging-negative temporal lobe epilepsy.

Intracranial EEG for seizure focus localization: evolving techniques, outcomes, complications, and utility of combining surface and depth electrodes.

Intracranial electroencephalography (iEEG) provides valuable information that guides clinical decision-making in patients undergoing epilepsy surgery, but it carries technical challenges and risks. The technical approaches used and reported rates of complications vary across institutions and evolve over time with increasing experience. In this report, the authors describe the strategy at the University of Iowa using both surface and depth electrodes and analyze outcomes and complications. The authors performed a retrospective review and analysis of all patients who underwent craniotomy and electrode implantation from January 2006 through December 2015 at the University of Iowa Hospitals and Clinics. The basic demographic and clinical information was collected, including electrode coverage, monitoring results, outcomes, and complications. The correlations between clinically significant complications with various clinical variables were analyzed using multivariate analysis. The Fisher exact test was used to evaluate a change in the rate of complications over the study period. Ninety-one patients (mean age 29 ± 14 years, range 3-62 years), including 22 pediatric patients, underwent iEEG. Subdural surface (grid and/or strip) electrodes were utilized in all patients, and depth electrodes were also placed in 89 (97.8%) patients. The total number of electrode contacts placed per patient averaged 151 ± 58. The duration of invasive monitoring averaged 12.0 ± 5.1 days. In 84 (92.3%) patients, a seizure focus was localized by ictal onset (82 cases) or inferred based on interictal discharges (2 patients). Localization was achieved based on data obtained from surface electrodes alone (29 patients), depth electrodes alone (13 patients), or a combination of both surface and depth electrodes (42 patients). Seventy-two (79.1%) patients ultimately underwent resective surgery. Forty-seven (65.3%) and 18 (25.0%) patients achieved modified Engel class I and II outcomes, respectively. The mean follow-up duration was 3.9 ± 2.9 (range 0.1-10.5) years. Clinically significant complications occurred in 8 patients, including hematoma in 3 (3.3%) patients, infection/osteomyelitis in 3 (3.3%) patients, and edema/compression in 2 (2.2%) patients. One patient developed a permanent neurological deficit (1.1%), and there were no deaths. The hemorrhagic and edema/compression complications correlated significantly with the total number of electrode contacts (p = 0.01), but not with age, a history of prior cranial surgery, laterality, monitoring duration, and the number of each electrode type. The small number of infectious complications precluded multivariate analysis. The number of complications decreased from 5 of 36 cases (13.9%) to 3 of 55 cases (5.5%) during the first and last 5 years, respectively, but this change was not statistically significant (p = 0.26). An iEEG implantation strategy that makes use of both surface and depth electrodes is safe and effective at identifying seizure foci in patients with medically refractory epilepsy. With experience and iterative refinement of technical surgical details, the risk of complications has decreased over time.

Risk factors for surgical site infection after intracranial electroencephalography monitoring for epilepsy in the pediatric population.

OBJECTIVE Intracranial electroencephalography (iEEG) monitoring is an important method of identifying the seizure focus in patients with medically refractory epilepsy. While previous studies have demonstrated low rates of surgical complications, reported rates of surgical site infection (SSI) are highly variable. To date, no studies have specifically evaluated the patient or operative risk factors contributing to SSI. The goals of this study were to examine the rate of SSI after iEEG monitoring for epilepsy workup in pediatric patients and to determine the variables that might contribute to the development of SSI. METHODS A retrospective analysis of hospital charts at the Hospital for Sick Children was performed for all patients who had undergone iEEG monitoring between 2000 and 2016. Univariate and multivariate analyses were performed to look for statistically significant variables in relation to SSI. RESULTS Among 199 patients eligible for analysis, 8 (4.0%) developed SSIs within a period ranging from 21 to 51 days postoperatively. Univariate analysis yielded 4 factors related to SSI: number of people present in the operating room on electrode insertion (p = 0.02), length of insertion surgery (p = 0.04), previous operation at the same surgical site (p = 0.04), and number of depth electrodes inserted (p = 0.01). Multivariate analysis revealed that both the number of people present during the implant operation (OR 0.08, 95% CI 0.01-0.70) and the number of depth electrodes inserted (OR 3.52, 95% CI 1.44-8.59) independently contributed to SSI. CONCLUSIONS This is the largest case series and the first comprehensive review of both patient and operative risk factors in the development of SSI from iEEG monitoring in a pediatric population. The authors' institution had a lower rate of infection than those in most other studies, which could be explained by their protocol of administering intravenous antibiotics perioperatively and post-implant removal antibiotics for 14 days. The authors found a correlation between SSI and the number of people present during the implant operation, as well as the number of depth electrodes; both may contribute to breaks in sterility.