KCNQ2 encephalopathy: delineation of the electroclinical phenotype and treatment response

Neonatal-onset epilepsies are rare conditions, mostly genetically determined, that can have a benign or severe phenotype.(1,2) There is recent recognition of de novo KCNQ2 mutations in patients with severe neonatal-onset epilepsy with intractable seizures and severe psychomotor impairment, termed KCNQ2 encephalopathy.(3,4) This is a rare condition and all patients reported so far were diagnosed well after the neonatal period.(3,4) We report on 3 new cases of KCNQ2 encephalopathy diagnosed in the neonatal period and studied with continuous video-EEG recording. We describe a distinct electroclinical phenotype and report on efficacy of antiepileptic drug (AED) therapies.

Hemiconvulsion-hemiplegia syndrome revisited: longitudinal MRI findings in 10 children

AIM

Hemiconvulsion-hemiplegia syndrome (HHS) is a rare severe epilepsy of infancy consisting of unilateral convulsive status epilepticus immediately followed by transient or lasting ipsilateral hemiplegia. HHS may occur either in patients with previous brain pathology or without any identified cause, so-called 'idiopathic HHS'.

METHOD

We retrospectively analysed clinical and MRI longitudinal findings of a series of 10 patients (six females, four males) presenting with HHS. Age at the study inclusion ranged from 2 years 6 months to 15 years (mean of 5 y 10 mo, median 4 y 2 mo). After defining magnetic resonance imaging (MRI) features as 'typical', i.e. strictly unilateral involvement, and 'atypical', i.e. bilateral, we compared clinical data from both groups. Cognitive level was assessed using Brunet-Lézine or Wechsler scales.

RESULTS

HHS occurred at a mean age of 20.5 months (range 8-48 mo). In all cases, status epilepticus lasted for more than 1 hour and was characterised by unilateral clonic seizures followed by ipsilateral hemiplegia (persistent in five patients). Two patients in this series died: the first from multi-organ failure 2 weeks after the status epilepticus and the other from a second episode of ipsilateral intractable febrile status epilepticus 3 years after the first episode. Early MRI (days 1-7 from status epilepticus) showed hemispheric cytotoxic oedema in all, extending to the contralateral side for one. T2 hyperintensity in the basal ganglia was disclosed in 70% of patients and in the hippocampus in 60%. After 1 month (in intermediate and chronic phases), all surviving patients but one showed hemispheric cortical atrophy corresponding to the regions involved during the early stage. Comparing clinical features of patients presenting with 'typical' features, to those with 'atypical' findings, the second group presented psychomotor delay before status epilepticus.

INTERPRETATION

This series underlines the major value of early MRI for the prompt diagnosis of HHS, and shows that involvement of subcortical structures has been underestimated. Hippocampal involvement is not constant.

FIRES and IHHE: Delineation of the syndromes

Idiopathic hemiconvulsion hemiplegia and epilepsy syndrome (IHHE) and febrile infection-related epilepsy syndrome (FIRES) are rare epileptic syndromes characterized by the occurrence of status epilepticus in a previously healthy child during or closely after a febrile episode. In both syndromes, there is no evidence of central nervous system infection (encephalitis) and the etiology remains unclear. Treatment is disappointing, particularly in FIRES, except for a response to ketogenic diet (KD) in half of patients. In IHHS, children develop hemispheric brain atrophy with contralateral hemiplegia, epilepsy, and a variable degree of cognitive deficit. Patients with FIRES develop refractory epilepsy with severe cognitive deficit affecting the temporal and frontal lobe functions. The role of inflammation is hypothesized with a vicious circle involving inflammation and seizure activity facilitated by brain maturation putting them under the concept of "acute encephalopathy with inflammation-mediated status epilepticus."

Encephalopathy in children with Dravet syndrome is not a pure consequence of epilepsy

Background

Dravet syndrome (DS) is currently considered as an epileptic encephalopathy, a condition in which epilepsy causes deterioration or developmental delay but preliminary data suggested that cognitive course may worsen independently from epilepsy. Our objective was to prospectively analyze the neuropsychological features in a large cohort of DS patients and its relationships with epilepsy and SCN1A mutation.

Methods

81 examinations were performed in 67 patients with typical DS (9m-24y, 15 longitudinally studied) using Brunet-Lezine (developmental/intelligence quotient [DQ/IQ] and DQ sub-scores), Achenbach, Conners, and a semi-quantitative psychomotor score (SQPS). We studied the correlation between DQ/IQ/SQPS and age, epilepsy characteristics, and whether patients presented SCN1A mutation.

Results

DQ/IQ significantly decreased with age (r = −.53, p < .001), from normal before 2y (mean 80, range 64–105) to low after 3y (mean 48, range 30–69), with hyperactivity and attention disorders hampering learning abilities especially up to 6y. However, raw (not age-adjusted) DQ sub-scores increased with age during the first decade, showing that there is no regression. We did not find any significant correlation between DQ/IQ at last evaluation and epilepsy data, i.e. first seizure (age, type, duration, fever), seizures during the course (type, fever sensitivity), status epilepticus (age of onset, number, fever), photosensitivity, and treatment, except for myoclonus and focal seizures which were associated with a lower QD/IQ after 3y. SCN1A mutated patients (n = 58) seemed to exhibit worse psychomotor course than non-mutated ones (n = 9) (severe SQPS in 26% vs 0%), although their epilepsy tended to be less severe (tonic seizures in 12% vs 44% [p = 0.04], first status epilepticus before 6 m in 26% vs 67% [p = .02], mean number of SE 2.5 vs 4.5 [p = .09]). DQ sub-scores were dissociated throughout the whole course: from onset hand-eye coordination was significantly lower than language, posture and sociability (p < .01). Dissociation seemed to be more frequent in mutated than in non-mutated patients (motor SQPS was normal for in 77% vs 44% [p = 0.017] whereas language SQPS was normal for 47% vs 100%).

Conclusions

Although psychomotor/cognitive delay declines with age, there is no regression. In addition, encephalopathy is not a pure consequence of epilepsy but SCN1A mutation seems to play an additional, direct role.

Early epileptic encephalopathies associated with STXBP1 mutations: Could we better delineate the phenotype?

STXBP1 (MUNC18.1), encoding syntaxin binding protein 1, is a gene causing epileptic encephalopathy. Mutations in STXBP1 have first been reported in early onset epileptic encephalopathy with suppression-bursts, then in infantile spasms and, more recently, in patients with non syndromic mental retardation without epilepsy. We analyzed clinical evolution and brain magnetic resonance imaging in 7 patients (6 females, 1 male) with early onset epileptic encephalopathies associated with STXBP1 mutations. We documented a peculiar brain MRI aspect characterized by frontal hypoplasia and a thin and dysmorphic corpus callosum. The course of the epilepsy was relatively benign. These clinical and neuroradiological features could orient the clinician in selecting patients' candidate to genetic testing for STXBP1 gene.

Transition and transfer from pediatric to adult health care in epilepsy: a families' survey on Dravet syndrome

We used a questionnaire to ascertain the perception of transition and transfer from pediatric to adult health-care system in patients with Dravet syndrome and their families. Sixty families received the questionnaire. We had a response rate of 85%. Sixty-one percent of patients experienced a transfer. Factors that positively impacted transfer were the quality of transition preparation (p<.000001), a longer duration of follow-up by the same child neurologist (p<.001), the availability of the child neurology staff (p<.01), a transfer into the adult health-care system after the age of 18 (p<.01), and a stable medical condition before transfer (p<.05). All families reported a positive experience in the pediatric health-care system. Child neurologists were considered as welcoming, available, and helpful. Their experience in the adult health-care system was similar to pediatric care. Almost all patients who experienced "transfer" reported no gap in this process.

Use of dietary therapy for status epilepticus

One of the newest and yet fastest growing indications for dietary therapy is the emergency treatment of refractory status epilepticus. Ten retrospective publications since 2008 have reported benefits in 32 children and adults, of whom 25 (78%) became seizure-free. Most of the patients who responded did so within 7 to 10 days of the initiation of nasogastrically administered ketogenic formulas. Encephalitis and febrile-illness related epilepsy syndrome causing status epilepticus highly refractory to antiepileptic drugs may be particularly amenable to dietary treatment. Prospective, multicenter studies are under way to help clarify who best will respond, how quickly, and the optimal diet duration after success.

Children often present with infantile spasms after herpetic encephalitis

PURPOSE

To determine what epilepsy types occur after herpetic encephalitis and what are the determinant factors for subsequent infantile spasms.

METHODS

We analyzed retrospectively the clinical history of 22 patients, referred to Necker and Saint Vincent de Paul Hospitals (Paris) through the French pediatric epilepsy network from March 1986 to April 2010 and who developed epilepsy some months after herpetic encephalitis. We focused on seizure semiology with video-electroencephalography (EEG) recording, and on neuroradiology and epilepsy follow-up.

KEY FINDINGS

Fourteen patients developed pharmacoresistant spasms, and eight developed focal epilepsy, but none had both. The patients who developed spasms were more frequently younger than 30 months at age of onset of epilepsy and had herpetic encephalitis earlier (mean 10.6 months of age) than those who developed focal epilepsy (mean 59.7 and 39.6 months, respectively). Epilepsy follow-up was similar in both groups (8.5 and 11 years, respectively). We found 26 affected cerebral areas; none alone was related to the development of epileptic spasms.

SIGNIFICANCE

Risk factors to develop epileptic spasms were to have had herpetic encephalitis early (mean 10 months); to be significantly younger at onset of epilepsy (mean 22.1 months); and to have cerebral lesions involving the insula, the hippocampus, and the temporal pole.

Management of subependymal giant cell astrocytoma (SEGA) associated with tuberous sclerosis complex (TSC): Clinical recommendations

Subependymal giant cell astrocytoma (SEGA) is a type of brain tumour that develops in 10-15% of individuals with tuberous sclerosis complex (TSC). SEGAs can be unilateral or bilateral, developing from benign subependymal nodules (hamartomas) located near the foramen of Monro. These are usually slow-growing, glialneuronal tumours that develop within the first 2 decades of life. Traditionally, the management of SEGA involved monitoring using periodic neuroimaging, and surgical resection of tumours that exhibited growth and/or caused clinical signs of intracranial hypertension. Recent clinical research has demonstrated that mammalian target of rapamycin (mTOR) inhibitors can induce partial regression of SEGA associated with TSC and so might provide an acceptable alternative to neurosurgery for these tumours. This report summarizes the clinical recommendations for the management of SEGA made by a panel of European experts in March 2012. Current treatment options and outstanding questions are outlined.

Novel compound heterozygous mutations in TBC1D24 cause familial malignant migrating partial seizures of infancy

Early-onset epileptic encephalopathies (EOEEs) are a group of rare devastating epileptic syndromes of infancy characterized by severe drug-resistant seizures and electroencephalographic abnormalities. The current study aims to determine the genetic etiology of a familial form of EOEE fulfilling the diagnosis criteria for malignant migrating partial seizures of infancy (MMPSI). We identified two inherited novel mutations in TBC1D24 in two affected siblings. Mutations severely impaired TBC1D24 expression and function, which is critical for maturation of neuronal circuits. The screening of TBC1D24 in an additional set of eight MMPSI patients was negative. TBC1D24 loss of function has been associated to idiopathic infantile myoclonic epilepsy, as well as to drug-resistant early-onset epilepsy with intellectual disability. Here, we describe a familial form of MMPSI due to mutation in TBC1D24, revealing a devastating epileptic phenotype associated with TBC1D24 dysfunction.

Experimental designs for small randomised clinical trials: an algorithm for choice

Background

Small clinical trials are necessary when there are difficulties in recruiting enough patients for conventional frequentist statistical analyses to provide an appropriate answer. These trials are often necessary for the study of rare diseases as well as specific study populations e.g. children. It has been estimated that there are between 6,000 and 8,000 rare diseases that cover a broad range of diseases and patients. In the European Union these diseases affect up to 30 million people, with about 50% of those affected being children. Therapies for treating these rare diseases need their efficacy and safety evaluated but due to the small number of potential trial participants, a standard randomised controlled trial is often not feasible. There are a number of alternative trial designs to the usual parallel group design, each of which offers specific advantages, but they also have specific limitations. Thus the choice of the most appropriate design is not simple.

Methods

PubMed was searched to identify publications about the characteristics of different trial designs that can be used in randomised, comparative small clinical trials. In addition, the contents tables from 11 journals were hand-searched. An algorithm was developed using decision nodes based on the characteristics of the identified trial designs.

Results

We identified 75 publications that reported the characteristics of 12 randomised, comparative trial designs that can be used in for the evaluation of therapies in orphan diseases. The main characteristics and the advantages and limitations of these designs were summarised and used to develop an algorithm that may be used to help select an appropriate design for a given clinical situation. We used examples from publications of given disease-treatment-outcome situations, in which the investigators had used a particular trial design, to illustrate the use of the algorithm for the identification of possible alternative designs.

Conclusions

The algorithm that we propose could be a useful tool for the choice of an appropriate trial design in the development of orphan drugs for a given disease-treatment-outcome situation.

A revisited strategy for antiepileptic drug development in children: designing an initial exploratory step

BACKGROUND

Randomized controlled trials (RCTs) in refractory paediatric epilepsy usually involve the two main types of epilepsy shared by children and adults, focal epilepsy and Lennox-Gastaut syndrome (LGS). Most other epilepsy syndromes, specifically paediatric, are excluded from drug development. In order to identify among them the candidate(s) for dedicated RCTs with a new drug, the European Medicine Agency (EMA) recently recommended proceeding in two steps: (1) an exploratory (prospective-observational) trial (POT) including a large variety of paediatric epilepsy syndromes and (2) a subsequent RCT in each of those that disclose a signal for possible efficacy.

OBJECTIVE

Our objective was to address the three following issues that have not been addressed by the EMA: (1) to determine a minimal threshold for this signal; (2) to establish a list of epilepsies to evaluate; and (3) to estimate the number of patients to include in such POTs.

METHODS

We extensively reviewed the POTs (including various syndromes) and RCTs reported in paediatric patients with uncontrolled epilepsy using MEDLINE (from 1990 to 2011) and the Cochrane library. We determined the threshold as the lowest percentage of responders observed in a POT with a positive corresponding RCT. The syndromes that reached this threshold in a POT were those to evaluate in an RCT. The minimal number of patients to include for each syndrome for a POT with a new antiepileptic drug was estimated in order to reach at least this threshold of responders with a 95 % confidence interval.

RESULTS

We found the minimal responder threshold to be 25 %. We identified eight epilepsy types/syndromes reaching this threshold and estimated for each of them the minimal sample needed: refractory focal epilepsy (n = 40), Lennox-Gastaut syndrome (n = 32), infantile spasms (n = 50), Dravet syndrome (n = 32), childhood absence epilepsy (n = 12), other symptomatic generalized epilepsy (n = 38), epileptic encephalopathy with continuous spikes and waves during sleep (n = 7) and epilepsy with myoclonic-astatic seizures (n = 4) [the two last samples may be underestimated due to the lack of RCTs in these conditions].

CONCLUSION

Among the eight epilepsy types/syndromes that we recommend to systematically include in exploratory trials using the POT procedure, we assume that, for the minimal sample given above, a responder threshold of 25 % will provide a reliable efficacy signal, to be confirmed by a dedicated RCT. This strategy should avoid missing new therapeutic possibilities for children with epilepsy and reduce the off-label use of drugs in paediatric neurology.

Genetics of idiopathic epilepsies

One of the most exciting areas in epilepsy has been the explosion in our understanding of the genetics of the epilepsies over the last decade. Built on a long history of careful clinical genetic studies of the epilepsies, the relatively recent discovery of epilepsy genes has enabled insights into pathways causing seizure disorders. A variety of mutational mechanisms can cause epilepsy resulting from different, and sometimes surprising, molecular processes such as copy number variation within the genome. The majority of known epilepsy genes encode ion channel subunits leading many of the genetic epilepsies to be regarded as channelopathies. Understanding how dysfunction of a mutant protein leads to hyperexcitability is key to understanding the pathophysiology of this group of serious and common childhood disorders. The architecture of the common genetic epilepsies following complex inheritance, where multiple genes are involved, is also beginning to be unraveled. The clinical approach to understanding the genetics of the epilepsies has matured and requires a detailed family history of seizures together with delineation of the child's epilepsy syndrome. Recognition of specific genetic epilepsy syndromes enables optimal treatment and prognostic and genetic counseling.

Sturge-Weber syndrome

Sturge-Weber syndrome (SWS) is a rare sporadic neurocutaneous syndrome defined by the association of a facial capillary malformation in the ophthalmic distribution of the trigeminal nerve, with ipsilateral vascular glaucoma and vascular malformation of the eye, and a leptomeningeal angioma. SWS is suspected at birth in the presence of facial angioma in the trigeminal nerve area. MRI with gadolinium enhancement and pondered T1, T2, FLAIR and diffusion sequences is today the technique of choice to visualize the leptomeningeal angioma or to suspect it by indirect signs, even before the development of neurological signs, from the first months of life. The prognosis of SWS with leptomeningeal angioma is related to the severity of neurological signs that are absent at birth and develop later in life (epilepsy, hemiparesis, and mental delay). Seizures are usually the presenting neurological symptom. Status epilepticus might inaugurate the epilepsy and remains frequent in infancy. Repetitive seizures are thought to increase the atrophy of brain tissue in regard to the leptomeningeal angioma. Preventive presymptomatic treatment with antiepileptic drugs is often recommended, and parents are trained to use rescue benzodiazepines in case of seizures. After epilepsy onset, in patients intractable to antiepileptic drugs, surgery should be considered.

Do mutations in SCN1B cause Dravet syndrome?

A homozygous SCN1B mutation was previously identified in a patient with early onset epileptic encephalopathy (EOEE) described as Dravet syndrome (DS) despite a more severe phenotype than DS. We investigated whether SCN1B mutations are a common cause of DS. Patients with DS who did not have a SCN1A sequencing mutation or copy number variation were studied. Genomic DNA was Sanger sequenced for mutations in the 6 exons of SCN1B. In 54 patients with DS recruited from four centres, no SCN1B mutations were identified. SCN1B mutation is not a common cause of DS.

Autoimmune and inflammatory epilepsies

The role of immunity and inflammation in epilepsy have long been suggested by the anticonvulsant activity of steroids in some infancy and childhood epilepsies. The role of fever and infection in exacerbating seizures due to possible proinflammatory molecules, the increased frequency of seizures in systemic autoimmune diseases like systemic lupus erythematous, and, recently, the detection of autoantibodies in some unexplained epilepsies reinforced the causal place of immunity and inflammation in epilepsies with unknown etiology. In this article, we summarize epilepsies where clinical and biologic data strongly support the pathogenic role of autoantibodies (e.g., limbic encephalitides, N-methyl-d-aspartate [NMDA] encephalitis) and epilepsies where immune-mediated inflammation occurs, but the full pathogenic cascade is either not clear (e.g., Rasmussen's encephalitis) or only strongly hypothesized (idiopathic hemiconvulsion-hemiplegia syndrome [IHHS] and fever-induced refractory epilepsy in school-aged children [FIRES]). We emphasize the electroclinical features that would help to diagnose these conditions, allowing early immunomodulating therapy. Finally, we raise some questions that remain unclear regarding diagnosis, mechanisms, and future therapies.

Management of epilepsy associated with tuberous sclerosis complex (TSC): clinical recommendations

Tuberous sclerosis complex (TSC) is a leading genetic cause of epilepsy. TSC-associated epilepsy generally begins during the first year of life, and is associated with neurodevelopmental and cognitive problems. Management is challenging and seizures tend to persist in a large proportion of patients despite pharmacological and surgical treatment. This report summarizes the clinical recommendations for the management of TSC-associated epilepsy made by a panel of European experts in March 2012. Current treatment options and outstanding questions are outlined.

Genome-wide association analysis of genetic generalized epilepsies implicates susceptibility loci at 1q43, 2p16.1, 2q22.3 and 17q21.32

Genetic generalized epilepsies (GGEs) have a lifetime prevalence of 0.3% and account for 20-30% of all epilepsies. Despite their high heritability of 80%, the genetic factors predisposing to GGEs remain elusive. To identify susceptibility variants shared across common GGE syndromes, we carried out a two-stage genome-wide association study (GWAS) including 3020 patients with GGEs and 3954 controls of European ancestry. To dissect out syndrome-related variants, we also explored two distinct GGE subgroups comprising 1434 patients with genetic absence epilepsies (GAEs) and 1134 patients with juvenile myoclonic epilepsy (JME). Joint Stage-1 and 2 analyses revealed genome-wide significant associations for GGEs at 2p16.1 (rs13026414, P(meta) = 2.5 × 10(-9), OR[T] = 0.81) and 17q21.32 (rs72823592, P(meta) = 9.3 × 10(-9), OR[A] = 0.77). The search for syndrome-related susceptibility alleles identified significant associations for GAEs at 2q22.3 (rs10496964, P(meta) = 9.1 × 10(-9), OR[T] = 0.68) and at 1q43 for JME (rs12059546, P(meta) = 4.1 × 10(-8), OR[G] = 1.42). Suggestive evidence for an association with GGEs was found in the region 2q24.3 (rs11890028, P(meta) = 4.0 × 10(-6)) nearby the SCN1A gene, which is currently the gene with the largest number of known epilepsy-related mutations. The associated regions harbor high-ranking candidate genes: CHRM3 at 1q43, VRK2 at 2p16.1, ZEB2 at 2q22.3, SCN1A at 2q24.3 and PNPO at 17q21.32. Further replication efforts are necessary to elucidate whether these positional candidate genes contribute to the heritability of the common GGE syndromes.

Stiripentol: an example of antiepileptic drug development in childhood epilepsies

The efficacy of stiripentol (STP) in Dravet Syndrome (DS) was discovered first in an exploratory study in pediatric pharmacoresistant epilepsies. This efficacy signal, used as a proof of concept, led to - two independent multicenter randomized, double-blind, placebo-controlled trials in DS patients: STICLO-France and STICLO-Italy. In adjunction to valproate and clobazam, STP demonstrated marked efficacy and these trials became the basis for the registration of STP as an orphan drug for DS. Although STP had previously shown antiepileptic activity, since it inhibits cytochromes P450, the increased plasma levels of clobazam (CLB), norclobazam (NCLB), and NCLB/CLB ratio reported in STICLO studies brought into question the activity of STP per se. Recent pharmacological studies demonstrated that (i) STP is a direct allosteric modulator of the GABA receptors at a site distinct from benzodiazepines; (ii) STP and CLB/NCLB act independently at GABA(A) receptors; (iii) their combination increases the maximum response beyond that of either drug alone. All these effects are independent of considerations of changes in metabolism. Some responders in STICLO studies failed to display any increase of plasmatic concentrations of NCLB/CLB ratio as STP could not inhibit CYP2C19 because of its inhibition by progabide or due to an inactivating CYP polymorphism. The responder rate proved to be in the same range whether the NCLB/CLB ratio increased or not. These analyses confirmed that the effects of STP cannot result from a simple pharmacokinetic interaction. We propose that the success of STP should serve as a model for AED development in rare pediatric epileptic syndromes.