Infantile spasms and encephalopathy without preceding neonatal seizures caused by KCNQ2 R198Q, a gain-of-function variant
Variants in KCNQ2 encoding for Kv7.2 neuronal K+ channel subunits lead to a spectrum of neonatal-onset epilepsies, ranging from self-limiting forms to severe epileptic encephalopathy. Most KCNQ2 pathogenic variants cause loss-of-function, whereas few increase channel activity (gain-of-function). We herein provide evidence for a new phenotypic and functional profile in KCNQ2-related epilepsy: infantile spasms without prior neonatal seizures associated with a gain-of-function gene variant. With use of an international registry, we identified four unrelated patients with the same de novo heterozygous KCNQ2 c.593G>A, p.Arg198Gln (R198Q) variant. All were born at term and discharged home without seizures or concern of encephalopathy, but developed infantile spasms with hypsarrhythmia (or modified hypsarrhythmia) between the ages of 4 and 6 months. At last follow-up (ages 3–11 years), all patients were seizure-free and had severe developmental delay. In vitro experiments showed that Kv7.2 R198Q subunits shifted current activation gating to hyperpolarized potentials, indicative of gain-of-function; in neurons, Kv7.2 and Kv7.2 R198Q subunits similarly populated the axon initial segment, suggesting that gating changes rather than altered subcellular distribution contribute to disease molecular pathogenesis. We conclude that KCNQ2 R198Q is a model for a new subclass of KCNQ2 variants causing infantile spasms and encephalopathy, without preceding neonatal seizures.
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Researchers at Elli Lilly and Co., in Indiana, have discovered a new compound that specifically targets neural circuits involved in epilepsy and could potentially be developed into an antiepileptic drug (AED). The findings are published in the leading scientific journal, Nature Medicine.
The compound, known as CERC-611, selectively blocks a protein associated with a receptor called AMPA found in the forebrain, an area involved in the generation of focal seizures. As the AMPA-associated protein is absent in most other parts of the brain, it is thought that blocking it will not cause side effects such as dizziness, lack of muscle coordination and falling (which are seen with other drugs that block the AMPA receptor directly).
Dr Michael Rogawski, a professor of neurology and pharmacology at the University of California, said:”Targeting these receptors may lead to improved antiseizure efficacy, safety and tolerability, and make a significant impact on treatment outcomes. No prior epilepsy treatment targets a subset of brain receptors involved in seizure generation in a regionally-selective fashion.”
The researchers tested the specificity of the compound in brain tissue obtained form an epilepsy patient. They then tested it in rodent models of epilepsy and found that it prevented multiple seizures without causing motor side effects.
Dr Uli Hacksell, CEO of Crecor, the company that is developing the potential drug said: “We believe CERC-611 has the potential to provide a true advancement in epilepsy therapy.”
The company hopes to file an investigational new drug application with the US Food and Drug Administration (FDA), and start a phase one clinical trial to test the compound, in 2017.
Author: Dr Özge Özkaya
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Increased subcortical oligodendroglia-like cells in pharmacoresistant focal epilepsy in children correlate with extensive epileptogenic zones
Cortical resections in epilepsy surgery tend to involve multiple lobes in children, compared to adults, partly due to underlying pathology. Oligodendroglia-like cells (OLCs) have been observed in surgical specimens from children with pharmacoresistant epilepsy. We hypothesize that OLCs recruit multiple-lobe epileptogenic zones in pediatric pharmacoresistant focal epilepsy.Methods
We examined the surgical specimens from 30 children who underwent epilepsy surgery (1.8- to 16.9-years-old; mean age 9.7 years). Immunohistochemical assays of OLCs were performed using Olig2, which is a marker of OLC. OLC populations in three sites (gray matter, gray–white matter junction, and white matter) were counted. We also performed immunohistochemical staining with neuronal nuclear antigen (NeuN) and glial fibrillary acidic protein (GFAP) for neuronal and astroglial markers, respectively. NeuN- and GFAP-positive cells were distinguished from OLCs. OLC results were compared with seizure types, scalp and intracranial video–electroencephalography (EEG), magnetic resonance imaging (MRI), surgical resection area, histopathologic diagnosis, and seizure outcome.Results
Histopathologic diagnosis consisted of 14 cases of focal cortical dysplasia (FCD; type I; 4, type II; 9, type III; one); 6 cases of oligodendrogliosis; 6 cases of astrocytic gliosis; 2 cases of hyaline protoplasmic astrocytopathy; and 2 cases of tuberous sclerosis. Fifteen children (50%) underwent multiple-lobe resections after intracranial video-EEG. There was a positive correlation between the number of resected electrodes and the OLC population in the white matter (correlation coefficient 0.581, p = 0.001) and at the gray–white matter junction– (correlation coefficient 0.426, p = 0.027). OLC populations in both areas were increased significantly in nine children with epileptic spasms (ES) (gray–white matter junction [p = 0.021] and white matter [p = 0.025]), and nine nonfocal ictal scalp EEG findings (gray–white matter junction [p = 0.04] and white matter [p = 0.042]). The OLC population in white matter was significantly increased in children with 11 nonfocal interictal scalp EEG findings (p = 0.01), with 15 multiple-lobe resections (p = 0.028).Significance
Pharmacoresistant epilepsy in children with increased OLCs presented with nonfocal epileptiform discharges on scalp EEG and ES, and they required multiple-lobe resections. We found increased populations of subcortical OLCs in the extensive epileptogenic zone.
Correlation of FDG-PET hypometabolism and SEEG epileptogenicity mapping in patients with drug-resistant focal epilepsy
Interictal [18F]fluorodeoxyglucose–positron emission tomography (FDG-PET) is used in the presurgical evaluation of patients with drug-resistant focal epilepsy. We aimed at clarifying its relationships with ictal high-frequency oscillations (iHFOs) shown to be a relevant marker of the seizure-onset zone.Methods
We studied the correlation between FDG-PET and epileptogenicity maps in an unselected series of 37 successive patients having been explored with stereo-electroencephalography (SEEG).Results
At the group level, we found a significant correlation between iHFOs and FDG-PET interictal hypometabolism only in cases of temporal lobe epilepsy. This correlation was found with HFOs, and the same comparison between FDG-PET and ictal SEEG power of lower frequencies during the same epochs did not show the same significance.Significance
This finding suggests that interictal FDG-PET and ictal HFOs may share common underlying pathophysiologic mechanisms of ictogenesis in temporal lobe epilepsy, and combining both features may help to identify the seizure-onset zone.
Epilepsy and autism spectrum disorder (ASD) often occur together in the same individual. However, it remains unknown whether siblings of children with ASD have an increased risk of epilepsy and vice versa. This study determines the risk of ASD and epilepsy among younger siblings of children with ASD and epilepsy.Design
The study included all children born in Denmark between January 1, 1980 and 31 December 2006 who participated in follow-up until December 31, 2012 (1,663,302 children). We used Cox regression to calculate the adjusted hazard ratio (aHR) and the Kaplan-Meier method to calculate the cumulative incidence.Results
The overall aHR of epilepsy in younger siblings increased by 70% (aHR 1.70, 95% confidence interval [CI] 1.34–2.16%) if the older sibling had ASD compared with siblings where the older sibling did not have ASD. The cumulative incidence of epilepsy at 20 years of age was 2.54% (95% CI 1.97–3.26%) if the older sibling had ASD, whereas the cumulative incidence of epilepsy at 20 years of age was 1.63% (95% CI 1.60–1.66%) if the older sibling did not have ASD. The overall aHR of ASD in younger siblings increased by 54% if the older sibling had epilepsy (aHR 1.54, 95% CI 1.32–1.80) compared with siblings where the older sibling did not have epilepsy. The cumulative incidence of ASD at 20 years of age was 2.06% (95% CI 1.84–2.32%) if the older sibling had epilepsy, whereas the cumulative incidence of ASD at 20 years of age was 1.27% (95% CI 1.25–1.29%) if the older sibling did not have epilepsy.Significance
The cross-disorder sibling risk of epilepsy and ASD was increased for the two disorders, which suggests that genes or environmental factors shared by family members may play a causal role in the co-occurrence of ASD and epilepsy.
In vivo studies of epilepsy typically use prolonged status epilepticus to generate recurrent seizures. However, reports on variable status duration have found discrete differences in injury after 40–50 min of seizures, suggesting a pathophysiologic sensitivity to seizure duration. In this report we take a multivariate cluster analysis to study a short duration status epilepticus model using in vivo 7T magnetic resonance spectroscopy (MRS) and histologic evaluation.Methods
The Hellier Dudek model was applied with 45 min of status epilepticus after which the animals were imaged twice, at 3 days and 3 weeks post–status epilepticus. Single voxel point resolved spectroscopy (PRESS) MRS was used to acquire data from the dentate gyrus and CA3 region of the hippocampus, assessing metabolite ratios to total creatine (tCr). In a subset of animals after the second imaging study, brains were analyzed histologically by Nissl staining.Results
A hierarchical cluster analysis performed on the 3-day data from 21 kainate-treated animals (dentate gyrus voxel) segregated into two clusters, denoted by KM (more injured, n = 6) and KL (less injured, n = 15). Although there was no difference in kainate dosing or seizure count between them, the metabolic pattern of injury was different. The KM group displayed the largest significant changes in neuronal and glial parameters; the KL group displayed milder but significant changes. At 3 weeks, the KL group returned to normal compared to controls, whereas the KM group persisted with depressed N-acetyl aspartate (NAA)/tCr, glutamate/tCr, and increased inositol/tCr and glutamine/tCr. The classification was also consistent with subsequent histologic patterns at 3 weeks.Significance
Although a short status period might be expected to generate a continuous distribution of metabolic injury, these data show that the short Hellier Dudek model appears to generate two levels of injury. The changes seen in segregated groups persisted into 3 weeks, and can be interpreted according to neuronal and glial biomarkers consistent with histology results.
The properties and structure of tissue can be visualized without labeling or preparation by multiphoton microscopy combining coherent anti-Stokes Raman scattering (CARS), addressing lipid content, second harmonic generation (SHG) showing collagen, and two-photon excited fluorescence (TPEF) of endogenous fluorophores. We compared samples of sclerotic and nonsclerotic human hippocampus to detect pathologic changes in the brain of patients with pharmacoresistant temporomesial epilepsy (n = 15). Multiphoton microscopy of cryosections and bulk tissue revealed hippocampal layering and micromorphologic details in accordance with reference histology: CARS displayed white and gray matter layering and allowed the assessment of axonal myelin. SHG visualized blood vessels based on adventitial collagen. In addition, corpora amylacea (CoA) were found to be SHG-active. Pyramidal cell bodies were characterized by intense cytoplasmic endogenous TPEF. Furthermore, diffuse TPEF around blood vessels was observed that co-localized with positive albumin immunohistochemistry and might indicate degeneration-associated vascular leakage. We present a label-free and fast optical approach that analyzes pathologic aspects of HS. Hippocampal layering, loss of pyramidal cells, and presence of CoA indicative of sclerosis are visualized. Label-free multiphoton microscopy has the potential to extend the histopathologic armamentarium for ex vivo assessment of changes of the hippocampal formation on fresh tissue and prospectively in vivo.
According to a study published in the journal Pharmacoepidemiology and Drug Safety, children exposed to antidepressants in the womb have an increased risk of being diagnosed with epilepsy later on if their mothers are diagnosed with depression during pregnancy*. A child’s risk of epilepsy also appears to increase if its mother takes antidepressants 2-6 months before, but not during, pregnancy.
Interestingly, the findings suggest that if a women takes antidepressants during pregnancy, but does not receive a clinical diagnosis of depression during this time, their child’s risk of epilepsy does not increase.
The study, conducted at Aarhus University Hospital, in Denmark, identified 734,237 Danish children born between 1997 and 2008. The researchers used the Danish National Registers to collect information about their epilepsy diagnoses, and about their mothers’ use of antidepressants and diagnoses of depression.
The results showed that, of the 734,237 children, 12,438 (1.7%) were born to women who took antidepressants between 1 month prior to conception and delivery. Amongst these 12,438, 5829 (0.8%) were diagnosed with epilepsy an average of 6.7 years later.
The researchers calculated that the children exposed to antidepressants before birth had (overall) a 27% higher risk of epilepsy compared with the children who were not exposed to antidepressants.
They then separated the data for cases where the mother took antidepressants during pregnancy and received (1)/ did not receive (2) a clinical diagnosis of depression during pregnancy. They found that for (1) the children had a 71% increased risk of epilepsy compared with unexposed children, but that for (2) there was actually no increase in risk compared with the unexposed group.
Children of women who took antidepressants 2-6 months before pregnancy, but not during pregnancy, were found to have a 36% increased risk of epilepsy compared with unexposed children. However, these women had a number of characteristics that could, themselves, have influenced the baby’s epilepsy risk; e.g. they were more likely to be older, to have a history of epilepsy/psychiatric disorders and to take antiepileptic/antipsychotic drugs.
The authors acknowledge that this study has a number of limitations, and they recommend further research to a) verify their findings and b) differentiate the effects of antidepressant medication from depression itself, upon the risk of epilepsy.
*In this article, reference to the diagnosis of depression ‘during pregnancy’ also extends to a diagnosis in the six months prior to pregnancy.
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Poor versus rich children with epilepsy have the same clinical course and remission rates but a less favorable social outcome: A population-based study with 25 years of follow-up
To explore the influence of several estimates of family socioeconomic status on the long-term clinical course and social outcomes of children with epilepsy.Methods
The Nova Scotia childhood epilepsy cohort is population based and includes all children in this Canadian province who developed epilepsy between 1977 and 1985. Eligible patients had ≥10 years of follow-up. Children with childhood absence epilepsy were excluded. Total family income at seizure onset was assessed at seizure onset and classified as “poor” (first quintile), “adequate” (second to third quintiles), and “well-off” (fourth to fifth quintiles). We also assessed parental education and home ownership. Social outcome was assessed in those with normal intelligence who were ≥18 years of age at the end of follow-up using a semistructured interview that explored eight adverse effects.Results
Of 584 patients, 421 (72%) were included. Average follow-up was 26 ± 5.6 years. Overall 137 families (33%) had “poor” income, 159 (38%) had “adequate income,” and 125 (30%) were “well-off.” Terminal remission of epilepsy occurred in 65% of the poor, 61% of the adequate, and 61% of the well-off (p = ns). Intractable epilepsy, status epilepticus, number of antiepileptic drugs (AEDs) used, and the number of generalized tonic–clonic or focal with secondary generalization seizures through the clinical course was the same in all groups. Home ownership did not predict remission. Neither paternal nor maternal education was associated with remission. Poor children had significantly more adverse social outcomes including failure to graduate from high school, unemployment, personal poverty, inadvertent pregnancy, and psychiatric diagnoses.Significance
In Nova Scotia with universal health care, coming from a poor or more affluent family does not seem to affect the clinical course or long-term seizure outcome of childhood epilepsy. Unfortunately children from poor families are less likely to have a good social outcome.
The behaviour of children with epilepsy could help identify those at a greater risk of severe psychiatric conditions, according to a study published in the journal, Epilepsia.
This finding is important, because it means that children who are identified in this way can be given the necessary care and treatment so that chronic mental health problems (which may negatively influence quality of life and increase the risk of suicide) are not carried into adulthood.
During the study, researchers led by Dr Rochelle Caplan, at the University of California, recruited 328 children with epilepsy and divided them into two groups: a ‘younger’ group (aged 5-12) and an ‘older’ group (aged 13-18). They then asked the parents of the children to complete the Child Behavior Checklist (CBCL) questionnaire, which includes 113 items to assess children’s behaviour.
The team also conducted psychiatric interviews with the children and their parents, to try and identify or diagnose some of the children with a psychiatric disorder (e.g. depression, anxiety and attention deficit and hyperactivity disorder (ADHD)).
The results showed that seven characteristics on the CBCL – clinginess, cruelty/bullying, perfectionism, nervousness, poor schoolwork, inattentiveness and sulkiness – were helpful in identifying/diagnosing children in the younger group with multiple psychiatric conditions, but not those with a single psychiatric condition.
Similarly, amongst the older group of children, three traits on the CBCL – disobedience at school, loner behaviour and lying/cheating – were found to be useful in identifying/diagnosing those with multiple psychiatric conditions (but again, not those with a single condition).
The authors conclude that CBCL is a simple and accurate screening tool, which could easily be used to identify children with epilepsy who are at an increased risk of multiple psychiatric conditions and need to be referred to a psychiatrist.
People with epilepsy have a higher risk of suicide compared with the general population, and the risk significantly increases if one or more psychiatric conditions are also present.
Author: Dr Özge Özkaya
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Antiepileptic drug (AED) treatment failures may occur because there is insufficient drug in the brain or because of a lack of relevant therapeutic response. Until now it has not been possible to measure these factors. It has been recently shown that the combination of transcranial magnetic stimulation and electroencephalography (TMS-EEG) can measure the effects of drugs in healthy volunteers. TMS-evoked EEG potentials (TEPs) comprise a series of positive and negative deflections that can be specifically modulated by drugs with a well-known mode of action targeting inhibitory neurotransmission. Therefore, we hypothesized that TMS-EEG can detect effects of two widely used AEDs, lamotrigine and levetiracetam, in healthy volunteers.Methods
Fifteen healthy subjects participated in a pseudo-randomized, placebo-controlled, double-blind, crossover design, using a single oral dose of lamotrigine (300 mg) and levetiracetam (3,000 mg). TEPs were recorded before and 120 min after drug intake, and the effects of drugs on the amplitudes of TEP components were statistically evaluated.Results
A nonparametric cluster-based permutation analysis of TEP amplitudes showed that AEDs both increased the amplitude of the negative potential at 45 msec after stimulation (N45) and suppressed the positive peak at 180 msec (P180). This is the first demonstration of AED-induced modulation of TMS-EEG measures.Significance
Despite the different mechanism of action that lamotrigine and levetiracetam exert at the molecular level, both AEDs impact the TMS-EEG response in a similar way. These TMS-EEG fingerprints observed in healthy subjects are candidate predictive markers of treatment response in patients on monotherapy with lamotrigine and levetiracetam.
Temporal behavior of seizures and interictal bursts in prolonged intracranial recordings from epileptic canines
Epilepsy is a chronic disorder, but seizure recordings are usually obtained in the acute setting. The chronic behavior of seizures and the interictal bursts that sometimes initiate them is unknown. We investigate the variability of these electrographic patterns over an extended period of time using chronic intracranial recordings in canine epilepsy.Methods
Continuous, yearlong intracranial electroencephalography (iEEG) recordings from four dogs with naturally occurring epilepsy were analyzed for seizures and interictal bursts. Following automated detection and clinician verification of interictal bursts and seizures, temporal trends of seizures, burst count, and burst–burst similarities were determined. One dog developed status epilepticus, the recordings of which were also investigated.Results
Multiple seizure types, determined by onset channels, were observed in each dog, with significant temporal variation between types. The first 14 days of invasive recording, analogous to the average duration of clinical invasive recordings in humans, did not capture the entirety of seizure types. Seizures typically occurred in clusters, and isolated seizures were rare. The count and dynamics of interictal bursts form distinct groups and do not stabilize until several weeks after implantation.Significance
There is significant temporal variability in seizures and interictal bursts after electrode implantation that requires several weeks to reach steady state. These findings, comparable to those reported in humans implanted with the NeuroPace Responsive Neurostimulator System (RNS) device, suggest that transient network changes following electrode implantation may need to be taken into account when interpreting or analyzing iEEG during evaluation for epilepsy surgery. Chronic, ambulatory iEEG may be better suited to accurately map epileptic networks in appropriate individuals.