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We investigated the association between human herpesvirus 6 (HHV‐6) and mesial temporal sclerosis (MTS) in 87 patients who had surgery for drug‐resistant epilepsy. Fifty‐four had MTS, 22 focal cortical dysplasia (FCD), four tumors, three vascular malformations, and three a history of encephalitis. We extracted DNA from fresh brain tissue immediately after surgery and performed viral detection with quantitative real‐time polymerase chain reaction (PCR) or digital droplet PCR specific for HHV‐6A and HHV‐6B. Tissue was studied with standard clinical techniques, including hematoxylin and eosin, glial fibrillary acidic protein, and NeuN stains. Twenty‐nine of 54 patients with MTS, six of 23 with focal cortical dysplasia (FCD), and one of three with a history of encephalitis were positive for HHV‐6 (P

Onset of many forms of epilepsy occurs after an initial epileptogenic insult or as a result of an identified genetic defect. Given that the precipitating insult is known, these epilepsies are, in principle, amenable to secondary prevention. However, development of preventive treatments is difficult because only a subset of individuals will develop epilepsy and we cannot currently predict which individuals are at the highest risk. Biomarkers that enable identification of these individuals would facilitate clinical trials of potential anti-epileptogenic treatments, but no such prognostic biomarkers currently exist. Several putative molecular, imaging, electroencephalographic and behavioural biomarkers of epileptogenesis have been identified, but clinical translation has been hampered by fragmented and poorly coordinated efforts, issues with inter-model reproducibility, study design and statistical approaches, and difficulties with validation in patients. These challenges demand a strategic roadmap to facilitate the identification, characterization and clinical validation of biomarkers for epileptogenesis. In this Review, we summarize the state of the art with respect to biomarker research in epileptogenesis and propose a five-phase roadmap, adapted from those developed for cancer and Alzheimer disease, that provides a conceptual structure for biomarker research.

Highlights • Multiscale image filters provide a good representation of local cortical appearance. • Most FCD lesions and some normal cortical regions appear as outliers in our model. • FCDs appear similar to the anterior insula and some paralimbic cortical regions. • Our constrained outlier detection approach allows for automated FCD detection., Objective Focal cortical dysplasias (FCDs) are a common cause of apparently non-lesional drug-resistant focal epilepsy. Visual detection of subtle FCDs on MRI is clinically important and often challenging. In this study, we implement a set of 3D local image filters adapted from computer vision applications to characterize the appearance of normal cortex surrounding the gray-white junction. We create a normative model to serve as the basis for a novel multivariate constrained outlier approach to automated FCD detection. Methods Standardized MPRAGE, T2 and FLAIR MR images were obtained in 15 patients with radiologically or histologically diagnosed FCDs and 30 healthy volunteers. Multiscale 3D local image filters were computed for each MR contrast then sampled onto the gray-white junction surface. Using an iterative Gaussianization procedure, we created a normative model of cortical variability in healthy volunteers, allowing for identification of outlier regions and estimates of similarity in normal cortex and FCD lesions. We used a constrained outlier approach following local normalization to automatically detect FCD lesions based on projection onto the mean FCD feature vector. Results FCDs as well as some normal cortical regions such as primary sensorimotor and paralimbic regions appear as outliers. Regions such as the paralimbic regions and the anterior insula have similar features to FCDs. Our constrained outlier approach allows for automated FCD detection with 80% sensitivity and 70% specificity. Significance A normative model using multiscale local image filters can be used to describe the normal cortical variability. Although FCDs appear similar to some cortical regions such as the anterior insula and paralimbic cortices, they can be identified using a constrained outlier detection approach. Our method for detecting outliers and estimating similarity is generic and could be extended to identification of other types of lesions or atypical cortical areas.

Summary Objective To analyze data from Seizure Tracker, a large electronic seizure diary, including comparison of seizure characteristics among different etiologies, temporal patterns in seizure fluctuations, and specific triggers. Methods Zero‐inflated negative binomial mixed‐effects models were used to evaluate temporal patterns of seizure events (during the day or week), as well as group differences in monthly seizure frequency between children and adults and between etiologies. The association of long seizures with seizure triggers was evaluated using a mixed‐effects logistic model with subject as the random effect. Incidence rate ratios (IRRs) and odds ratios were reported for analyses involving zero‐inflated negative binomial and logistic mixed‐effects models, respectively. Results A total of 1,037,909 seizures were logged by 10,186 subjects (56.7% children) from December 2007 to January 2016. Children had more frequent seizures than adults did (median monthly seizure frequency 3.5 vs. 2.7, IRR 1.26; p 5 or >30 min) had a higher proportion of the following triggers when compared with shorter seizures: “Overtired or irregular sleep,” “Bright or flashing lights,” and “Emotional stress” (p

Structural magnetic resonance imaging (MRI) is of fundamental importance to the diagnosis and treatment of epilepsy, particularly when surgery is being considered. Despite previous recommendations and guidelines, practices for the use of MRI are variable worldwide and may not harness the full potential of recent technological advances for the benefit of people with epilepsy. The International League Against Epilepsy Diagnostic Methods Commission has thus charged the 2013-2017 Neuroimaging Task Force to develop a set of recommendations addressing the following questions: (1) Who should have an MRI? (2) What are the minimum requirements for an MRI epilepsy protocol? (3) How should magnetic resonance (MR) images be evaluated? (4) How to optimize lesion detection? These recommendations target clinicians in established epilepsy centers and neurologists in general/district hospitals. They endorse routine structural imaging in new onset generalized and focal epilepsy alike and describe the range of situations when detailed assessment is indicated. The Neuroimaging Task Force identified a set of sequences, with three-dimensional acquisitions at its core, the harmonized neuroimaging of epilepsy structural sequences-HARNESS-MRI protocol. As these sequences are available on most MR scanners, the HARNESS-MRI protocol is generalizable, regardless of the clinical setting and country. The Neuroimaging Task Force also endorses the use of computer-aided image postprocessing methods to provide an objective account of an individual's brain anatomy and pathology. By discussing the breadth and depth of scope of MRI, this report emphasizes the unique role of this noninvasive investigation in the care of people with epilepsy.

Background Recurrent seizure risks in HIV-positive people with new-onset seizure are largely unknown, making it challenging to offer optimal recommendations regarding antiepileptic drug (AED) initiation. Existing outcomes data is limited, and risk factor identification requires a diagnostic assessment, which is often unavailable in regions heavily effected by HIV, like sub-Saharan Africa. Methods HIV-positive Zambian adults with new-onset seizure were enrolled in a prospective cohort study to determine seizure recurrence and risk factors for recurrence. Seizure etiology was evaluated, and recurrent seizures and medication usage were assessed during clinic visits. Due to unexpectedly high mortality rates, predictors of death were evaluated using proportional hazards with Gray’s test to compare cumulative incidence functions for recurrent seizure across groups adjusting for the competing outcome of death. Results 95 patients were enrolled (mean age 37 years, 43% female, 83% with Karnofsky > 50) and followed for a mean of 293 days (median 241 (IQR: 29–532)). At presentation, 50 (53%) were in status epilepticus. The majority (91, 85%) had advanced HIV disease and 65 (68%) were not on combined antiretroviral therapy (cART). After extensive workup, seizure etiology remained unknown in 16 (17%). Average time to cART initiation after enrollment was 61 days. During follow up, 37 (39%) died and 23 (24%) had recurrent seizure. Most deaths (25/37, 68%) occurred in the first 60 days post-index seizure. Individuals with advanced HIV were more likely to die (HR: 19.1 [95% CI: 1.1–333.4]) as were those whose seizure etiology remained unknown (HR: 2.2 [95% CI: 1.1–4.4]). Among participants that survived from enrolment to the end of data collection on 10 May 2013 (n = 58), 20 (34%) experienced recurrent seizures. Conclusions New-onset seizure among HIV-positive Zambian adults is associated with high mortality despite good functional status prior to presentation. Advanced HIV infection and failure to identify an underlying seizure etiology are associated with greater mortality. Recurrent seizures occur in over a third of survivors within only 2 years of follow-up. This provides evidence to support AED initiation after first seizure in HIV-positive individuals with advanced HIV disease at the time of presentation though the risks of AED-cART interactions remain a concern and warrant further study.

Location data are becoming easier to obtain and are now bundled with other metadata in a variety of biomedical research applications. At the same time, the level of sophistication required to protect patient privacy is also increasing. In this article, we provide guidance for institutional review boards (IRBs) to make informed decisions about privacy protections in protocols involving location data. We provide an overview of some of the major categories of technical algorithms and medical–legal tools at the disposal of investigators, as well as the shortcomings of each. Although there is no “one size fits all” approach to privacy protection, this article attempts to describe a set of practical considerations that can be used by investigators, journal editors, and IRBs.

Objective:To identify the etiology of new-onset seizure in HIV-infected Zambian adults and identify risk factors for seizure recurrence.Methods:A prospective cohort study enrolling HIV-infected adults with new-onset seizure within 2 weeks of index seizure obtained clinical, laboratory, and neuroimaging data to determine seizure etiology. Participants were followed to identify risk factors for seizure recurrence. Risk factors for mortality were examined as mortality rates were unexpectedly high.Results:Eighty-one patients with CSF for analysis were enrolled and followed for a median of 306 days (interquartile range 61–636). Most (91%) were at WHO stage III/IV and 66 (81%) had a pre-seizure Karnofsky score ≥50. Prolonged or multiple seizures occurred in 46 (57%), including 12 (15%) with status epilepticus. Seizure etiologies included CNS opportunistic infections (OI) in 21 (26%), hyponatremia in 23 (28%), and other infections in 8 (10%). OIs included Cryptococcus (17%), JC virus (7%) and 5% each for tuberculosis, cytomegalovirus, and varicella-zoster virus. No etiology could be identified in 16 (20%). Thirty (37%) patients died during follow-up and 20 (25%) had recurrent seizures with survival being the only identifiable risk factor.Conclusions:HIV-infected adults with new-onset seizure in Zambia often have advanced HIV disease with OI being the most frequent seizure etiology. Seizure recurrence is common but no risk factors for recurrence other than survival were identified. These findings suggest an urgent need for immune reconstitution in this population. Initiating treatment for seizure prophylaxis where only enzyme-inducing antiepileptic medications are available could threaten antiretroviral efficacy.

Epilepsy can be a devastating disorder. In addition to debilitating seizures, epilepsy can cause cognitive and emotional problems with reduced quality of life. Therefore, the major aim is to prevent the disorder in the first place: identify, detect, and reverse the processes responsible for its onset, and monitor and treat its progression. Epilepsy often occurs following a latent period of months to years (epileptogenesis) as a consequence of a brain insult, such as head trauma, stroke, or status epilepticus. Although this latent period clearly represents a therapeutic window, we are not able to stratify patients at risk for long-term epilepsy, which is prerequisite for preventative clinical trials. Moreover, because of the length of the latent period, an early biomarker for treatment response would be of high value. Finally, mechanistic biomarkers of epileptogenesis may provide more profound insight in the process of disease development.

Summary Objective Functional magnetic resonance imaging (fMRI) activation of the mesial temporal lobe (MTL) may be important for epilepsy surgical planning. We examined MTL activation and lateralization during language fMRI in children and adults with focal epilepsy. Methods One hundred forty-two controls and patients with left hemisphere focal epilepsy (pediatric: epilepsy, n = 17, mean age = 9.9 ± 2.0; controls, n = 48; mean age = 9.1 ± 2.6; adult: epilepsy, n = 20, mean age = 26.7 ± 5.8; controls, n = 57, mean age = 26.2 ± 7.5) underwent 3T fMRI using a language task (auditory description decision task). Image processing and analyses were conducted using Statistical Parametric Mapping (SPM8); regions of interest (ROIs) included MTL, Broca's area, and Wernicke's area. We assessed group and individual MTL activation, and examined degree of lateralization. Results Patients and controls (pediatric and adult) demonstrated group and individual MTL activation during language fMRI. MTL activation was left lateralized for adults, but less so in children (p's < 0.005). Patients did not differ from controls in either age group. Stronger left-lateralized MTL activation was related to older age (p = 0.02). Language lateralization (Broca's and Wernicke's) predicted 19% of the variance in MTL lateralization for adults (p = 0.001), but for not children. Significance Language fMRI may be used to elicit group and individual MTL activation. The developmental difference in MTL lateralization and its association with language lateralization suggests a developmental shift in lateralization of MTL function, with increased left lateralization across the age span. This shift may help explain why children have better memory outcomes following resection compared to adults.

International audience; OBJECTIVE:To develop a better understanding of mechanisms of seizures and long-term epileptogenesis using neurocysticercosis.METHODS:A workshop was held bringing together experts in epilepsy and epileptogenesis and neurocysticercosis.RESULTS:Human neurocysticercosis and parallel animal models offer a unique opportunity to understand basic mechanisms of seizures. Inflammatory responses to degenerating forms and later-stage calcified parasite granulomas are associated with seizures and epilepsy. Other mechanisms may also be involved in epileptogenesis.SIGNIFICANCE:Naturally occurring brain infections with neurocysticercosis offer a unique opportunity to develop treatments for one of the world's most common causes of epilepsy and for the development of more general antiepileptogenic treatments. Key advantages stem from the time course in which an acute seizure heralds a start of the epileptogenic process, and radiographic changes of calcification and perilesional edema provide biomarkers of a chronic epileptic state.

Glucose metabolism has been associated with magnitude of blood oxygen level-dependent (BOLD) signal and connectivity across subjects within the default mode and dorsal attention networks. Similar correlations within subjects across the entire brain remain unexplored. [18F]-fluorodeoxyglucose positron emission tomography ([18F]-FDG PET), [11C]-flumazenil PET, and resting-state functional magnetic resonance imaging (fMRI) scans were acquired in eight healthy individuals and nine with temporal lobe epilepsy (TLE). Regional metabolic rate of glucose (rMRGlu) was correlated with amplitude of low frequency fluctuations (ALFFs) in the fMRI signal, global fMRI connectivity (GC), regional homogeneity (ReHo), and gamma-aminobutyric acid A—binding potential (GABAA BPND) across the brain. Partial correlations for ALFFs, GC, and ReHo with GABAA BPND were calculated, controlling for rMRGlu. In healthy subjects, significant positive correlations were observed across the brain between rMRGlu and ALFF, ReHo and GABAA BPND, and between ALFFs and GABAA BPND, controlling for rMRGlu. Brain-wide correlations between rMRGlu and ALFFs were significantly lower in TLE patients, and correlations between rMRGlu and GC were significantly greater in TLE than healthy subjects. These results indicate that the glutamatergic and GABAergic systems are coupled across the healthy human brain, and that ALFF is related to glutamate use throughout the healthy human brain. TLE may be a disorder of altered long-range connectivity in association with glutamate function.

Dear Editors, Carpio and Romo have emphasized the limitations in our understanding of symptomatic seizures and the epileptogenic process that follows in some, but not all patients with neurocysticercosis. Their letter also highlights a critical need for careful, systematic studies of clinical and molecular biomarkers in these patients. Fundamental knowledge gained from these patients could be extrapolated to many other causes of epilepsy. We are glad that in these aspects the authors agree with us on the potential usefulness of neurocysticercosis to unravel the pathophysiology of seizures and epilepsy in neurocysticercosis as well as in other seizure disorders. Our report is not a general review of neurocysticercosis and accordingly does not discuss other issues raised by the Carpio and Romo. The disease is relatively unstudied and many points controversial, so there is room for differences of opinion. For a number of reasons, this is not the forum to discuss these differences. However, our group of epilepsy and neurocysticercosis experts believe most evidence suggests that a small proportion, rather than a “few people with NC” develop epilepsy and that the evidence implicating neurocysticercois as a cause of epilepsy, we believe, is quite strong. Supporting evidence originates from number of kinds of information including numerous epidemiology reports, follow up of treated patients, and studies implicating specific calcifications as seizure foci in patients with epilepsy. In the later specific calcified lesions in patients with epilepsy have been implicated by their semiology and EEG findings implicating specific calcifications in about 50%-60% of patients studied. Similarly, whether repeated seizures over an extended period of time arising from an inflammatory focus is epilepsy or is a series of acute symptomatic seizures is important from a pathophysiology point of view, but applying outdated definitions of epilepsy to recurrent seizures in neurocysticercosis only begs for an improved classification scheme.

Epilepsy is both a disease of the brain and the mind. Here, we present the second of two papers with extended summaries of selected presentations of the Third International Congress on Epilepsy, Brain and Mind (April 3-5, 2014; Brno, Czech Republic). Humanistic, biologic, and therapeutic aspects of epilepsy, particularly those related to the mind, were discussed. The extended summaries provide current overviews of epilepsy, cognitive impairment, and treatment, including brain functional connectivity and functional organization; juvenile myoclonic epilepsy; cognitive problems in newly diagnosed epilepsy; SUDEP including studies on prevention and involvement of the serotoninergic system; aggression and antiepileptic drugs; body, mind, and brain, including pain, orientation, the "self-location", Gourmand syndrome, and obesity; euphoria, obsessions, and compulsions; and circumstantiality and psychiatric comorbidities.

In HIV-positive individuals with first seizure, we describe neuroimaging findings, detail clinical and demographic risk factors for imaging abnormalities, and evaluate the relationship between imaging abnormalities and seizure recurrence to determine if imaging abnormalities predict recurrent seizures. Among 43 participants (mean 37.4 years, 56% were male), 16 (37%) were on antiretroviral drugs, 32 (79%) had advanced HIV disease, and (28) 66% had multiple seizures and/or status epilepticus at enrollment. Among those with cerebrospinal fluid studies, 14/31 (44%) had opportunistic infections (OIs). During follow-up, 9 (21%) died and 15 (35%) experienced recurrent seizures. Edema was associated with OIs (odds ratio: 8.79; confidence interval: 1.03-236) and subcortical atrophy with poorer scores on the International HIV Dementia Scale) (5.2 vs. 9.3; P=0.002). Imaging abnormalities were not associated with seizure recurrence or death (P>0.05). Seizure recurrence occurred in at least a third and over 20% died during follow-up. Imaging was not predictive of recurrent seizure or death, but imaging abnormalities may offer additional diagnostic insights in terms of OI risk and cognitive impairment.

SUCCINIC SEMIALDEHYDE DEHYDROGENASE (SSADH) DEFICIENCY (OMIM # 271980) IS ONE OF THE FEW GENETIC DISORDERS AFFECTING GABA METABOLISM and homeostasis. The clinical phenotype is generally nonspecific, featuring seizures, developmental delay, intellectual disability, delayed or absent speech, hypotonia, behavioral problems, and ataxia, with a typically static clinical course.1 Neuroimaging has most consistently demonstrated abnormalities in the globus pallidus, subthalamic nucleus, and cerebellar dentate nucleus.2 The biochemical hallmark is accumulation of γ-hydroxybutyric acid (GHB) (Figure 1). In addition, there is significant elevation in GABA in physiologic fluids as well as brain parenchyma, as measured by MR spectroscopy with special editing.3,4 GHB may act directly as a partial weak GABAB receptor agonist or as a direct neuromodulator on GHB receptors at pharmacologic concentrations, in addition to its interconversion to GABA.5 Exogenous GHB administration is associated with disinhibition, drowsiness, and ultimately coma at high doses.6 Chronic GHB administration in patients with narcolepsy-cataplexy increases delta sleep and suppresses REM intrusions with decreased awakenings and percentage of time awake during stage REM.7 We hypothesized that patients with SSADH deficiency have increased symptoms of sleep disorders and abnormal sleep architecture characterized by increased delta sleep and decreased stage REM sleep. Figure 1 Biochemical Pathway of GABA Metabolism.

To investigate acute effects of intra-amygdalar excitatory amino acid administration on blood flow, relaxation time and apparent diffusion coefficient in rat brain.Several days after MR-compatible cannula placement in right basolateral amygdala, anesthetized rats were imaged at 7 T. Relative cerebral blood flow (CBF) was measured before and 60 min after infusion of 10 nmol KA, cAMPA, ATPA, or normal saline using arterial spin labeling. Quantitative T(2) and diffusion-weighted images were acquired. rCBF, T(2) and ADC values were evaluated in bilateral basolateral amygdala, hippocampus, basal ganglia, frontal and parietal regions.KA led to the highest, and ATPA lowest bilateral rCBF increases. Time courses varied among drugs. T(2) for KA and AMPA was higher while ADC was lower for KA.Intra-amygdalar injection of GluR agonists evoked bilateral seizure activity and increased rCBF, greater for KA and AMPA than selective ATPA GluR5 activation.

Summary Purpose: We undertook a systematic review of the evidence on disparities in epilepsy with a focus on North American data (Canada, United States, and the English-speaking Caribbean). Methods: We identified and evaluated: access to and outcomes following medical and surgical treatment, disability, incidence and prevalence, and knowledge and attitudes. An exhaustive search (1965–2007) was done, including: (1) disparities by socioeconomic status (SES), race/ethnicity, age, or education of subgroups of the epilepsy population; or (2) disparities between people with epilepsy (PWE) and healthy people or with other chronic illnesses. Results: From 1,455 citations, 278 eligible abstracts were identified and 44 articles were reviewed. Comparative research data were scarce in all areas. PWE have been shown to have lower education and employment status; among PWE, differences in access to surgery have been shown by racial/ethnic groups. Aboriginals, women, and children have been shown to differ in use of health resources. Poor compliance has been shown to be associated with lower SES, insufficient insurance, poor relationship with treating clinicians, and not having regular responsibilities. Discussion: Comprehensive, comparative research on all aspects of disparities in epilepsy is needed to understand the causes of disparities and the development of any policies aimed at addressing health disparities and minimizing their impact.

Background: Autosomal dominant partial epilepsy with auditory features (ADPEAF) is an idiopathic focal epilepsy syndrome with auditory symptoms or receptive aphasia as major ictal manifestations, frequently associated with mutations in the leucine-rich, glioma inactivated 1 ( LGI1 ) gene. Although affected subjects do not have structural abnormalities detected on routine MRI, a lateral temporal malformation was identified through high resolution MRI in one family. We attempted to replicate this finding and to assess auditory and language processing in ADPEAF using fMRI and magnetoencephalography (MEG). Methods: We studied 17 subjects (10 affected mutation carriers, 3 unaffected carriers, 4 noncarriers) in 7 ADPEAF families, each of which had a different LGI1 mutation. Subjects underwent high-resolution structural MRI, fMRI with an auditory description decision task (ADDT) and a tone discrimination task, and MEG. A control group comprising 26 volunteers was also included. Results: We found no evidence of structural abnormalities in any of the 17 subjects. On fMRI with ADDT, subjects with epilepsy had significantly less activation than controls. On MEG with auditory stimuli, peak 2 auditory evoked field latency was significantly delayed in affected individuals compared to controls. Conclusions: These findings do not support the previous report of a lateral temporal malformation in autosomal dominant partial epilepsy with auditory features (ADPEAF). However, our fMRI and magnetoencephalography data suggest that individuals with ADPEAF have functional impairment in language processing.

To evaluate the relationship between hippocampal volume loss, depression, and epilepsy.There is a significantly increased incidence of depression and suicide in patients with epilepsy. Both epilepsy and depression are associated with reduced hippocampal volumes, but it is uncertain whether patients with both conditions have greater atrophy than those with epilepsy alone. Previous studies used depression measures strongly weighted to current state, and did not necessarily assess the influence of chronic major depressive disorder ("trait"), which could have a greater impact on hippocampal volume.Fifty-five epilepsy patients with complex partial seizures (CPS) confirmed by electroencephalography (EEG) had three-dimensional (3D)-spoiled gradient recall (SPGR) acquisition magnetic resonance imaging (MRI) scans for hippocampal volumetric analysis. Depression screening was performed with the Beck Depression Inventory (BDI, 51 patients) and with the structured clinical inventory for DSM-IV (SCID, 34 patients). For the BDI, a score above 10 was considered mild to moderate, above 20 moderate to severe, and above 30 severe depression. MRI and clinical analysis were performed blinded to other data. Statistical analysis was performed with Systat using Student's t test and analysis of variance (ANOVA).There was a significant interaction between depression detected on SCID, side of focus, and left hippocampal volume. Patients with a diagnosis of depression and a right temporal seizure focus had significantly lower left hippocampal volume. A similar trend for an effect of depression on right hippocampal volume in patients with a right temporal focus did not reach statistical significance.Our results suggest that patients with right temporal lobe epilepsy and depression have hippocampal atrophy that cannot be explained by epilepsy alone.

Background Human herpesvirus-6 (HHV-6) is a β-herpesvirus with 90% seroprevalence that infects and establishes latency in the central nervous system. Two HHV-6 variants are known: HHV-6A and HHV-6B. Active infection or reactivation of HHV-6 in the brain is associated with neurological disorders, including epilepsy, encephalitis, and multiple sclerosis. In a preliminary study, we found HHV-6B DNA in resected brain tissue from patients with mesial temporal lobe epilepsy (MTLE) and have localized viral antigen to glial fibrillary acidic protein (GFAP)–positive glia in the same brain sections. We sought, first, to determine the extent of HHV-6 infection in brain material resected from MTLE and non-MTLE patients; and second, to establish in vitro primary astrocyte cultures from freshly resected brain material and determine expression of glutamate transporters. Methods and Findings HHV-6B infection in astrocytes and brain specimens was investigated in resected brain material from MTLE and non-MTLE patients using PCR and immunofluorescence. HHV-6B viral DNA was detected by TaqMan PCR in brain resections from 11 of 16 (69%) additional patients with MTLE and from zero of seven (0%) additional patients without MTLE. All brain regions that tested positive by HHV-6B variant-specific TaqMan PCR were positive for viral DNA by nested PCR. Primary astrocytes were isolated and cultured from seven epilepsy brain resections and astrocyte purity was defined by GFAP reactivity. HHV-6 gp116/54/64 antigen was detected in primary cultured GFAP-positive astrocytes from resected tissue that was HHV-6 DNA positive—the first demonstration of an ex vivo HHV-6–infected astrocyte culture isolated from HHV-6–positive brain material. Previous work has shown that MTLE is related to glutamate transporter dysfunction. We infected astrocyte cultures in vitro with HHV-6 and found a marked decrease in glutamate transporter EAAT-2 expression. Conclusions Overall, we have now detected HHV-6B in 15 of 24 patients with mesial temporal sclerosis/MTLE, in contrast to zero of 14 with other syndromes. Our results suggest a potential etiology and pathogenic mechanism for MTLE., Steve Jacobson and colleagues report finding human herpesvirus-6B DNA in brain resections from 11 of 16 patients with mesial temporal lobe epilepsy, strengthening the evidence for a role for this virus in this condition., Editors' Summary Background. Epilepsy is a common brain disorder caused by a sudden, excessive electrical discharge in a cluster of neurons—the cells that transmit electrical messages between the body and the brain. Its symptoms depend on which part of the brain is affected by this electrical firestorm and how far the disturbance spreads. When only part of the brain is affected (a partial seizure or fit), patients may see or smell strange things, recall forgotten memories, or have part of their body jerk uncontrollably. When the electrical disturbance spreads across the whole brain (a generalized seizure), there may be loss of consciousness and/or the whole body may become rigid or jerk. Epilepsy is usually controlled with anti-epileptic drugs or, in very severe focal cases, surgery to the area of the brain where the seizure starts. Although head injuries or brain tumors can trigger epilepsy, the cause of most cases of epilepsy is unknown. Why Was This Study Done? Knowing what causes epilepsy might lead to better treatments for it. One possibility is that infections trigger epilepsy. The researchers in this study asked whether infections with human herpesvirus 6B (HHV-6B) are associated with a common type of epilepsy called mesial temporal lobe epilepsy (MTLE). Patients with MTLE often have extensive scarring in the hippocampus, a brain region responsible for memory that lies deep within a bigger region called the temporal lobe. Hippocampal scarring and MTLE are associated with a history of fever-induced fits, and HHV-6B infection can cause such fits in young children. Most people become infected with HHV-6B (or the closely related HHV-6A) early in life. The virus then remains latent for years within the brain and elsewhere. Given these facts and a previous investigation that showed that brain tissue from several patients with MTLE contained HHV-6B, the researchers reasoned that it was worth investigating HHV-6B as a cause of MTLE. What Did the Researchers Do and Find? The researchers first looked for HHV-6B DNA in brain tissue surgically removed from patients with MTLE or another type of epilepsy. Tissue from 11 of 16 patients with MTLE (but from 0 of 7 control patients) contained HHV-6B DNA. When the researchers grew astrocytes (a type of brain cell) from some of these samples, only those from HHV-6B DNA-positive samples from patients with MTLE expressed an HHV-6-specific protein. Next, the researchers investigated in detail a patient with MTLE who had four sequential operations to control his epilepsy. This patient's hippocampus, which was removed in his first operation, contained a higher level of HHV-6B DNA than the tissues removed in later operations. After the fourth operation (which removed half of his brain and cured his epilepsy), astrocytes grown from the temporal lobe and the frontal/parietal lobe (a brain region next to the temporal lobe) but not the frontal and occipital lobes contained HHV-6B DNA and expressed a viral protein. The researchers also measured the production by these various astrocytes of a substance that moves glutamate (an amino acid that also acts as a neurotransmitter) across cell membranes—MTLE has been associated with a glutamate transporter deficiency. Consistent with this, astrocytes from the patient's temporal lobe made no glutamate transporter mRNA (mRNA is an essential precursor for protein to be produced). Finally, infection of astrocytes isolated from a patient without MTLE with HHV-6B greatly reduced expression of glutamate transporter in these astrocytes. What Do These Findings Mean? These findings, together with those from the previous study, reveal that nearly two-thirds of patients with MTLE (but no patients with other forms of epilepsy) have an active HHV-6B infection in the brain region where their epilepsy originates. Overall, they provide strong support for the idea that HHV-6B infections might cause MTLE, particularly given the results obtained from the patient whose condition only improved after multiple brain operations had removed all the virally infected material. Furthermore, the demonstration that HHV-6B infection reduces glutamate transporter expression in astrocytes suggests that HHV-6B infection might cause astrocyte dysfunction. This dysfunction could lead to injury of the sensitive neurons in the hippocampus and trigger MTLE. Additional patients now need to be studied both to confirm the association between HHV-6B infection and MTLE and to discover exactly how this virus triggers epilepsy. Additional Information. Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0040180. MedlinePlus encyclopedia page on epilepsy (in English and Spanish) World Health Organization fact sheet on epilepsy (in English, French, Spanish, Russian, Arabic, and Chinese) US National Institute for Neurological Disorders and Stroke epilepsy information page (in English and Spanish) UK National Health Service Direct information for patients on epilepsy (in several languages) Neuroscience for kids, an educational Web site prepared by Eric Chudler (University of Washington, Seattle, Washington, United States), who also has a site that includes information on epilepsy and a list of links to epilepsy organizations (mainly in English but some sections in other languages as well) A short scientific article on human herpes virus 6 in the journal Emerging Infectious Diseases

Periventricular White Matter Flumazenil Binding and Postoperative Outcome in Hippocampal Sclerosis Hammers A, Koepp MJ, Brooks DJ, Duncan JS Epilepsia 2005;46(6):944–948 Purpose In patients with hippocampal sclerosis (HS), anterior temporal lobe resection offers the possibility of a long-lasting suppression of seizures in two-thirds of patients. White matter (WM) [11C]flumazenil volume of distribution (FMZ-Vd) reflects the number of neuronal cell bodies in WM. Our objective was to correlate WM FMZ-Vd in patients with unilateral HS and postsurgical outcome. Methods We performed [11C]flumazenil positron emission tomography ([11C]FMZ-PET) in 15 patients with refractory mesial temporal lobe epilepsy (mTLE) and a quantitative MRI diagnosis of unilateral HS subsequently histologically verified in all cases. Median follow-up was 7 years (range, 6–9 years). Metabolite-corrected arterial plasma input functions and spectral analysis were used to generate parametric images of [11C]FMZ-Vd. Statistical parametric mapping (SPM99) with explicit masking was used to investigate the entire brain volume including WM. Results Eight patients had Engel class IA outcome (completely seizure-free since surgery), and seven were not seizure-free. Comparison of seizure-free patients with those who continued to have seizures after surgery revealed areas of increased FMZ binding around the posterior horns of the ipsilateral (z = 3.7) and contralateral (z = 2.7) ventricles in those with suboptimal outcomes. Conclusions Preoperative [11C]FMZ-PET can detect periventricular increases of WMFMZ binding, implying heterotopic neurons in WM, in patients with mTLE. The presence of such increases correlates with a poorer outcome.

Studies in experimental models have suggested a potential role for serotonergic transmission in epilepsy, and interest in this research has been increased by the development of positron emission tomography (PET) ligands that can be used to study 5-hydroxytryptamine (5-HT) receptors and transporters. The serotonergic system is very complex. At least 13 distinct G protein–coupled 5-HT receptors and one ligand-gated ion channel receptor (5-HT3) are divided into seven distinct classes (5-HT1 to 5-HT7) ( 1 ). The receptors vary widely in their distribution and effects, innervating vascular structures and gut smooth muscle as well as neuronal tissue. Several receptor subtypes may be relevant to epilepsy.

International audience; OBJECTIVE: To identify age-dependent activation patterns of verbal fluency with functional MRI (fMRI). BACKGROUND: Few fMRI language studies have been performed in children, and none provide comparison data to adult studies. Normative data are important for interpretation of similar studies in patients with epilepsy. METHODS: A total of 10 normal children (5 boys, 5 girls; mean age, 10.7 years; range, 8.1 to 13.1 years) and 10 normal adults (5 men, 5 women; mean age, 28.7 years; range, 19.3 to 48 years) were studied on a 1.5-T Signa MRI scanner using BOLD echo planar imaging of the frontal lobes with a verbal fluency paradigm, covert word generation to letters. Studies were analyzed with a cross-correlation algorithm (r = 0.7). A region-of-interest analysis was used to determine the extent, magnitude, and laterality of brain activation. RESULTS: Children and adults activated similar regions, predominantly in left inferior frontal cortex (Broca's area) and left middle frontal gyrus (dorsolateral prefrontal cortex). Children had, on average, 60% greater extent of activation than adults, with a trend for greater magnitude of activation. Children also had significantly more right hemisphere and inferior frontal gyrus activation than adults. CONCLUSIONS: In a test of verbal fluency, children tended to activate cortex more widely than adults, but activation patterns for fluency appear to be established by middle childhood. Thus, functional MRI using verbal fluency paradigms may be applied to pediatric patient populations for determining language dominance in anterior brain regions. The greater activation found in children, including the right inferior frontal gyrus, may reflect developmental plasticity for the ongoing organization of neural networks, which underlie language capacity.