The borderland of epilepsy: clinical and molecular features of phenomena that mimic epileptic seizures

[Epileptic seizure and migraine attack: A revisit from the "Borderland of Epilepsy" to clinical implementation of infraslow activity/DC shifts in scalp EEG]

Migraine attacks, especially ones with aura, have symptoms similar to epileptic seizures, and the two may sometimes be difficult to differentiate clinically. However, the characteristic minute-by-minute symptom development and progress within 60 ‍min is useful for diagnosis. Although the details of its pathophysiology remain unsolved, cortical spreading depolarization (CSD) is one of the main pathogenetic factors. In epilepsy, clinical data have shown that ictal DC shifts could reflect impaired homeostasis of extracellular potassium by astrocyte dysfunction. Ictal DC shifts were found to be difficult to detect by scalp EEG, but can be clinically recorded from the seizure focus using wide-band EEG method. The similarity between DC shifts and CSD has been gaining attention from the neurophysiology point of view. The clinical implementation of infraslow activity/DC shifts analysis of scalp EEG is expected to elucidate further the pathophysiology of migraine, which may lie in the borderland of epilepsy.

National audit of pathways in epileptic seizure referrals (NAPIER): A national, multicentre audit of first seizure clinics throughout the UK and Ireland

BACKGROUND

Current guidelines set clinical standards for the management of suspected first seizures and epilepsy. We aimed to assess if these standards are being met across first seizure clinics nationally, to describe variations in care and identify opportunities for service delivery improvement.

METHODS

Multicentre audit assessing the care of adults (≥16 years) referred to first seizure clinics from 31st December 2019 going backwards (30 consecutive patients per centre). Patients with pre-existing diagnosis of epilepsy were excluded. Anonymised referral, clinic, and follow-up data are reported with descriptive statistics.

RESULTS

Data provided for 727 patients from 25 hospitals in the UK and Ireland (median age 41 years [IQR 26-59], 52% males). Median time to review was 48 days (IQR 26-86), with 13.8% (IQR 3.3%-24.0%) of patients assessed within 2 weeks. Seizure recurrence was seen in 12.7% (IQR 6.6%-17.4%) of patients awaiting first appointment. Documentation for witness accounts and driving advice was evident in 85.0% (IQR 74.0%-100%) and 79.7% (IQR 71.2%-96.4%) of first seizure/epilepsy patients, respectively. At first appointment, discussion of sudden unexpected death in epilepsy was documented in 30.1% (IQR 0%-42.5%) of patients diagnosed with epilepsy. In epilepsy patients, median time to MRI neuroimaging was 37 days [IQR 22-56] and EEG was 30 days [IQR 19-47]. 30.4% ([IQR 0%-59.5%]) of epilepsy patients were referred to epilepsy nurse specialists.

CONCLUSIONS

There is variability nationally in the documented care of patients referred to first seizure clinics. Many patients are facing delays to assessment with epilepsy specialists with likely subsequent impact on further management.

Clinical and Instrumental Characterization of Patients With Late-Onset Epilepsy

Epilepsy is classically considered a childhood disease. However, it represents the third most frequent neurological condition in the elderly, following stroke, and dementia. With the progressive aging of the general population, the number of patients with Late-Onset Epilepsy (LOE) is constantly growing, with important economic and social consequences, in particular for the more developed countries where the percentage of elderly people is higher. The most common causes of LOE are structural, mainly secondary to cerebrovascular or infectious diseases, brain tumors, trauma, and metabolic or toxic conditions. Moreover, there is a growing body of evidence linking LOE with neurodegenerative diseases, particularly Alzheimer's disease (AD). However, despite a thorough characterization, the causes of LOE remain unknown in a considerable portion of patients, thus termed as Late-Onset Epilepsy of Unknown origin (LOEU). In order to identify the possible causes of the disease, with an important impact in terms of treatment and prognosis, LOE patients should always undergo an exhaustive phenotypic characterization. In this work, we provide a detailed review of the main clinical and instrumental techniques for the adequate characterization of LOE patients in the clinical practice. This work aims to provide an easy and effective tool that supports routine activity of the clinicians facing LOE.

Borderlands of Migraine and Epilepsy

Background

The complex relationship between migraine and epilepsy has frequently been described to represent a clinical and electrographic "borderland." These two conditions share clinical expressions such as paroxysmal and chronic nature, as well as semiology, particularly visual phenomenon.

Objective

We aimed to review the current literature on the overlapping phenomena of migraine and epilepsy.

Materials and Methods

We searched the PubMed for relevant literature and conducted a narrative review on migraine and epilepsy.

Results

Migraine and epilepsy share a complex and pathophysiologically intriguing relationship. The International Classification of Headache Disorders, 3^rd edition (ICHD-3) makes diagnostic provisions for migraine aura-triggered seizures (Subchapter 1.4.4) and headache attributed to epileptic seizure (Subchapter 7.6), the latter being further categorized as 7.6.1 Ictal epileptic headache, and 7.6.2  post-ictal headache. Neurological conditions such as certain channelopathies and epilepsy syndromes exhibit both conditions within their phenotypic spectrum, suggesting shared genetic and molecular underpinnings. Diagnostic confusion may arise, particularly between occipital epilepsy and the visual aura of migraine. Antiseizure medications may be effective for the treatment of migraines that occur in concert with epilepsy.

Conclusions

Migraine and epilepsy share several clinical features and have intertwined genetic and molecular underpinnings, which may contribute to common pathogenesis. Electroencephalography may be useful as a diagnostic tool in selected cases.

Pathophysiological Bases of Comorbidity in Migraine

Despite that it is commonly accepted that migraine is a disorder of the nervous system with a prominent genetic basis, it is comorbid with a plethora of medical conditions. Several studies have found bidirectional comorbidity between migraine and different disorders including neurological, psychiatric, cardio- and cerebrovascular, gastrointestinal, metaboloendocrine, and immunological conditions. Each of these has its own genetic load and shares some common characteristics with migraine. The bidirectional mechanisms that are likely to underlie this extensive comorbidity between migraine and other diseases are manifold. Comorbid pathologies can induce and promote thalamocortical network dysexcitability, multi-organ transient or persistent pro-inflammatory state, and disproportionate energetic needs in a variable combination, which in turn may be causative mechanisms of the activation of an ample defensive system with includes the trigeminovascular system in conjunction with the neuroendocrine hypothalamic system. This strategy is designed to maintain brain homeostasis by regulating homeostatic needs, such as normal subcortico-cortical excitability, energy balance, osmoregulation, and emotional response. In this light, the treatment of migraine should always involves a multidisciplinary approach, aimed at identifying and, if necessary, eliminating possible risk and comorbidity factors.

Paroxysmal Genetic Movement Disorders and Epilepsy

Paroxysmal movement disorders include paroxysmal kinesigenic dyskinesia, paroxysmal non-kinesigenic dyskinesia, paroxysmal exercise-induced dyskinesia, and episodic ataxias. In recent years, there has been renewed interest and recognition of these disorders and their intersection with epilepsy, at the molecular and pathophysiological levels. In this review, we discuss how these distinct phenotypes were constructed from a historical perspective and discuss how they are currently coalescing into established genetic etiologies with extensive pleiotropy, emphasizing clinical phenotyping important for diagnosis and for interpreting results from genetic testing. We discuss insights on the pathophysiology of select disorders and describe shared mechanisms that overlap treatment principles in some of these disorders. In the near future, it is likely that a growing number of genes will be described associating movement disorders and epilepsy, in parallel with improved understanding of disease mechanisms leading to more effective treatments.

Sleep-Related Hypermotor Epilepsy: Etiology, Electro-Clinical Features, and Therapeutic Strategies

Sleep-related hypermotor epilepsy (SHE) is a group of clinical syndromes with heterogeneous etiologies. SHE is difficult to diagnose and treat in the early stages due to its diverse clinical manifestations and difficulties in differentiating from non-epileptic events, which seriously affect patients' quality of life and social behavior. The overall prognosis for SHE is unsatisfactory, but different etiologies affect patients' prognoses. Surgical treatment is an effective method for carefully selected patients with refractory SHE; nevertheless, preoperative assessment remains challenging because of the low sensitivity of noninvasive scalp electroencephalogram and imaging to detect abnormalities. However, through a careful analysis of semiology, the clinician can deduce the potential epileptogenic zone. This paper summarizes the research status of the background, etiology, electro-clinical features, diagnostic criteria, prognosis, and treatment of SHE to provide a more in-depth understanding of its pathophysiological mechanism, improve the accuracy in the diagnosis of this group of syndromes, and further explore more targeted therapy plans.

Epilepsy in the elderly: Unique challenges in an increasingly prevalent population

Elderly individuals (aged at least 60 or 65 years) represent a rapidly growing segment of the population. The incidence and prevalence of epilepsy is higher in this age group than in any other. Diagnosing epilepsy in the elderly can be challenging because the causes and clinical manifestations of seizures often differ as compared with younger individuals. Particular differential diagnoses, such as syncope and amyloid spells, are commonly encountered in the elderly population. A diagnosis of epilepsy has important implications in the older adult, many of which already present a variety of concomitant complex medical problems, such as cognitive impairment, comorbid cerebrovascular disease, and frailty. The treatment of epilepsy in the elderly is complicated by a variety of factors related to aging, including physiological changes, medical comorbidities, and polypharmacy. In this narrative review, we will address the descriptive epidemiology, clinical presentation, differential diagnosis, diagnostic evaluation, treatment, and prognosis of epilepsy in the elderly individual.

Consensus statement for the management of generalized tonic-clonic seizures in Spain

OBJECTIVE

To develop recommendations for the management of patients with primary or secondary generalized tonic-clonic seizures (GTCS) based on best evidence and experience.

METHODS

The Delphi methodology was followed. A multidisciplinary panel of 10 experts was established, who defined the scope, users and preliminary recommendations. Systematic and narrative reviews of the current literature were performed to assess data on the risk of sudden unexpected death in epilepsy and the efficacy and safety of add-on therapy in patients with GTCS. Twenty-five definitive recommendations were generated which were then graded on a scale of 1 (totally disagree) to 10 (totally agree) by the experts and 45 neurologists. Consensus was reached if at least 70% of the participants applied a score of ≥7. Each recommendation was then assigned a level of evidence, a grade of agreement and a grade of recommendation. The entire process was supervised by an expert methodologist.

RESULTS

Overall, 24 out of 25 recommendations achieved consensus. These included specific recommendations on diagnosis, evaluation and treatment. The recommendations also emphasized the importance of proper psychological evaluation and effective communication between patients and health professionals, and the importance of patient and family education and support.

SIGNIFICANCE

The recommendations generated by this consensus can be used as a guide for the diagnosis and management of patients with GTCS.

First seizure presentations in adults: beyond assessment and treatment

Almost 10% of people will experience at least one seizure over a lifetime. Although common, first seizures are serious events and warrant careful assessment and management. First seizures may be provoked by acute or remote symptomatic factors including life-threatening metabolic derangements, drug toxicity or structural brain lesions. An unprovoked first seizure may herald the onset of epilepsy and may be accompanied by medical and psychiatric illnesses. Accidents, injuries and death associated with first seizures are likely under-reported. The cognitive and emotional impact of first seizures is often neglected. Evaluation of a patient presenting with a first seizure requires careful history-taking and early specialist assessment, however optimal management strategies have not been extensively investigated. Further, advances in technology and the role of eHealth interventions such as telemedicine may be of value in the care of patients who have experienced a first seizure. This article reviews the impact and implications of first seizures beyond the scope provided in current guidelines which tend to focus on assessment and management. It examines the effect of first seizures on the well-being of patients; assesses morbidity and premature mortality in first seizures and discusses current and future directions to optimise safety and health of people with first seizures, with a focus on adult patients. Recognition of these issues is essential to provide adequate care for people with first seizures.

Syncope in Pediatric Practice

Syncope is defined as a sudden, self-limited loss of consciousness and postural tone followed by spontaneous and complete recovery without any neurological sequelae. It is one of the most common paroxysmal disorders in children and adolescents. The three major causes of syncope in children are neural, cardiovascular and other non-cardiovascular causes. The common unifying mechanism is transient global hypoperfusion of the brain. The diagnosis is primarily clinical and objective laboratory investigations add little to the diagnosis in children especially in neurocardiogenic subtype. Specific management depends on the underlying cause of syncope in children. For cardiac causes, management includes early referral to the pediatric cardiology specialist. When paroxysmal non-epileptic events are suspected, child psychology or psychiatry consultation should be sought to identify the stressors and counseling. For neurocardiogenic syncope, the main objective of treatment is to prevent recurrent events to improve the quality of life, psychological stress and school absenteeism by behavior and lifestyle modifications followed by drugs in refractory cases. The prognosis is excellent for neurocardiogenic syncope and is variable based on the underlying pathology in cardiogenic cases. As syncope is not a disease in itself but a symptom of an underlying disorder; hence, all children with syncope require assessment to exclude an underlying life-threatening cardiac or non-cardiac disorder.

[Psychogenic non epileptic seizures : Differential diagnostic features]

Psychogenic nonepileptic seizures (PNES) are to be considered in the differential diagnosis of a transient loss of consciousness. Their discrimination from syncope, epileptic seizures or vascular events can be difficult and requires profound knowledge about the semiology and clinical presentation of PNES and their differential diagnoses. Erroneous diagnoses and the resulting therapies lead to elevated morbidity, elevated costs and a poorer outcome. The aim of the present article is to provide an overview on PNES and their delineation from the clinical pictures of epilepsy and syncope.

Epilepsy

Epilepsy affects all age groups and is one of the most common and most disabling neurological disorders. The accurate diagnosis of seizures is essential as some patients will be misdiagnosed with epilepsy, whereas others will receive an incorrect diagnosis. Indeed, errors in diagnosis are common, and many patients fail to receive the correct treatment, which often has severe consequences. Although many patients have seizure control using a single medication, others require multiple medications, resective surgery, neuromodulation devices or dietary therapies. In addition, one-third of patients will continue to have uncontrolled seizures. Epilepsy can substantially impair quality of life owing to seizures, comorbid mood and psychiatric disorders, cognitive deficits and adverse effects of medications. In addition, seizures can be fatal owing to direct effects on autonomic and arousal functions or owing to indirect effects such as drowning and other accidents. Deciphering the pathophysiology of epilepsy has advanced the understanding of the cellular and molecular events initiated by pathogenetic insults that transform normal circuits into epileptic circuits (epileptogenesis) and the mechanisms that generate seizures (ictogenesis). The discovery of >500 genes associated with epilepsy has led to new animal models, more precise diagnoses and, in some cases, targeted therapies.

Tourette’s syndrome and its borderland

The Gilles de la Tourette syndrome (or Tourette’s syndrome) has a prevalence of 1% of children with a wide range of severity and associated comorbidities. The last 20 years have seen advances in the understanding of the syndrome’s complex genetics and underlying neurobiology. Investigation with imaging and neurophysiology techniques indicate it is a neurodevelopmental condition with dysfunction of basal ganglia–cortical interactions, which are now also being studied in animal models. There is also increasing evidence for treatments although it often remains difficult to manage. First-line options include neuroleptics, other drugs and specialised behavioural treatments. Deep brain stimulation is an evolving field, not yet fully established. This review focuses on the phenomenology of tics, how to assess and manage the syndrome, and uses examples of atypical cases to explore the characteristics and limits of its clinical spectrum.

Comorbid Epilepsy and Developmental Disorders in Congenital Long QT Syndrome With Life-Threatening Perinatal Arrhythmias

OBJECTIVES

Given the association of long QT syndrome (LQTS) and neurological disorders, we speculated that the more severe LQTS phenotype, perinatal LQTS, would exhibit more frequent comorbid neurodevelopmental anomalies than LQTS without perinatal arrhythmias (nonperinatal LQTS).

BACKGROUND

Congenital LQTS with life-threatening perinatal arrhythmias (perinatal LQTS) has a poor life prognosis.

METHODS

Twenty-one consecutive LQTS patients diagnosed before 1 year of age at our institution and 3 previously reported perinatal LQTS patients with neurological seizures were enrolled. In total, the clinical course was evaluated in 24 patients.

RESULTS

Among 21 infantile LQTS patients, 5 of 6 with perinatal LQTS (83%) were diagnosed with epilepsy and 4 (67%) with developmental disorders, but none with nonperinatal LQTS were. The total development quotient by Kinder Infant Development Scale scores was 17 to 72 (median 67) in 5 epileptic perinatal LQTS. In the 8 perinatal LQTS patients with neurological disorders, including 3 previously reported cases, epileptic seizures occurred at 2 days to 2.5 years of age and 5 had developmental disorders. Mutations in these 8 patients were located in the transmembrane loop of KCNH2, and D3/S4-S5 linker, D4/S4, or the D4/S6 segment of SCN5A.

CONCLUSIONS

A high comorbidity of neurodevelopmental anomalies was observed in perinatal LQTS. Mutations in patients with neurological comorbidities were in loci linked to LQTS with a severe cardiac phenotype. These observations indicate the possibility that neurological disorders in perinatal LQTS are manifested as neurological phenotypes associated with severe cardiac phenotypes, while we could not completely exclude another possibility that those were caused by a brain perfusion injury.

Natural history of canine paroxysmal movement disorders in Labrador retrievers and Jack Russell terriers

Delineation of the typical disease progression in canine paroxysmal dyskinesia (PD) may assist in evaluating therapeutic agents during clinical trials. Our objective was to establish the natural disease course in a group of dogs diagnosed with PD that received no medication. Fifty-nine dogs (36 Labradors, 23 JRTs) with clinically confirmed PD and a follow-up of ≥3 years were retrospectively reviewed. Dogs with PD had a young onset, were triggered by startle or sudden movements, and had a male bias (75%) with the majority being entire sample population. Twenty-one dogs (36%) had at least one event comprising cluster episodes. Episode duration and frequency varied dramatically, even within an individual. Median follow-up was 7 years. No concurrent disease was identified in any dog that was investigated. The natural history was self-limiting with 32% entering remission and an improvement in 75%. Episodes reduced in terms of frequency and duration in Labradors and JRTs respectively. Remission was lower in dogs with cluster episodes than those without. These findings suggest that the diagnostic yield of advanced neuroimaging techniques in dogs with video footage and historical data supporting PD, without neurological deficits, is low. The presence of cluster episodes is of predictive value for the prognosis of canine PD. Future research should be cautious in reporting treatment response for PD without first considering the spontaneous remission rate and improvements in untreated dogs documented in this study.

Resource efficient data compression algorithms for demanding, WSN based biomedical applications

During the last few years, medical research areas of critical importance such as Epilepsy monitoring and study, increasingly utilize wireless sensor network technologies in order to achieve better understanding and significant breakthroughs. However, the limited memory and communication bandwidth offered by WSN platforms comprise a significant shortcoming to such demanding application scenarios. Although, data compression can mitigate such deficiencies there is a lack of objective and comprehensive evaluation of relative approaches and even more on specialized approaches targeting specific demanding applications. The research work presented in this paper focuses on implementing and offering an in-depth experimental study regarding prominent, already existing as well as novel proposed compression algorithms. All algorithms have been implemented in a common Matlab framework. A major contribution of this paper, that differentiates it from similar research efforts, is the employment of real world Electroencephalography (EEG) and Electrocardiography (ECG) datasets comprising the two most demanding Epilepsy modalities. Emphasis is put on WSN applications, thus the respective metrics focus on compression rate and execution latency for the selected datasets. The evaluation results reveal significant performance and behavioral characteristics of the algorithms related to their complexity and the relative negative effect on compression latency as opposed to the increased compression rate. It is noted that the proposed schemes managed to offer considerable advantage especially aiming to achieve the optimum tradeoff between compression rate-latency. Specifically, proposed algorithm managed to combine highly completive level of compression while ensuring minimum latency thus exhibiting real-time capabilities. Additionally, one of the proposed schemes is compared against state-of-the-art general-purpose compression algorithms also exhibiting considerable advantages as far as the compression rate is concerned.

Headache in epilepsy: prevalence and clinical features

BACKGROUND

Headache and epilepsy are two relatively common neurological disorders and their relationship is still a matter of debate. Our aim was to estimate the prevalence and clinical features of inter-ictal (inter-IH) and peri-ictal headache (peri-IH) in patients with epilepsy.

METHODS

All patients aged ≥ 17 years referring to our tertiary Epilepsy Centre were consecutively recruited from March to May 2011 and from March to July 2012. They underwent a semi-structured interview including the International Classification Headache Disorders (ICHD-II) criteria to diagnose the lifetime occurrence of headache.χ(2)-test, t-test and Mann-Whitney test were used to compare clinical variables in patients with and without inter-IH and peri-IH.

RESULTS

Out of 388 enrolled patients 48.5 % had inter-IH: migraine in 26.3 %, tension-type headache (TTH) in 19.1 %, other primary headaches in 3.1 %. Peri-IH was observed in 23.7 %: pre-ictally in 6.7 %, ictally in 0.8 % and post-ictally in 19.1 %. Comparing patients with inter-ictal migraine (102), inter-ictal TTH (74) and without inter-IH (200), we found that pre-ictal headache (pre-IH) was significantly represented only in migraineurs (OR 3.54, 95 % CI 1.88-6.66, P < 0.001). Post-ictal headache (post-IH) was significantly associated with both migraineurs (OR 2.60, 95 % CI 1.85-3.64, P < 0.001) and TTH patients (OR 2.05, 95 % CI 1.41-2.98, P < 0.001). Moreover, post-IH was significantly associated with antiepileptic polytherapy (P < 0.001), high seizure frequency (P = 0.002) and tonic-clonic seizures (P = 0.043).

CONCLUSIONS

Migraine was the most represented type of headache in patients with epilepsy. Migraineurs are more prone to develop pre-IH, while patients with any inter-IH (migraine or TTH) are predisposed to manifest a post-IH after seizures.

Transient loss of consciousness and syncope

Syncope describes a sudden and brief transient loss of consciousness (TLOC) with postural failure due to cerebral global hypoperfusion. The term TLOC is used when the cause is either unrelated to cerebral hypoperfusion or is unknown. The most common causes of syncopal TLOC include: (1) cardiogenic syncope (cardiac arrhythmias, structural cardiac diseases, others); (2) orthostatic hypotension (due to drugs, hypovolemia, primary or secondary autonomic failure, others); (3) neurally mediated syncope (cardioinhibitory, vasodepressor, and mixed forms). Rarely neurologic disorders (such as epilepsy, transient ischemic attacks, and the subclavian steal syndrome) can lead to cerebal hypoperfusion and syncope. Nonsyncopal TLOC may be due to neurologic (epilepsy, sleep attacks, and other states with fluctuating vigilance), medical (hypoglycemia, drugs), psychiatric, or post-traumatic disorders. Basic diagnostic workup of TLOC includes a thorough history and physical examination, and a 12-lead electrocardiogram (ECG). Blood testing, electroencephalogram (EEG), magnetic resonance imaging (MRI) of the brain, echocardiography, head-up tilt test, carotid sinus massage, Holter monitoring, and loop recorders should be obtained only in specific contexts. Management strategies involve pharmacologic and nonpharmacologic interventions, and cardiac pacing.

Epilepsy and the cortical vestibular system: tales of dizziness and recent concepts

Cortical representations of the vestibular system are now well recognized. In contrast, the fact that epilepsy can affect these systems, provoking transient vestibular symptoms, is less known. Focal seizures may nonetheless manifest by prominent vestibular changes ranging from mild unsteadiness to true rotational vertigo. Most often these symptoms are associated with other subjective manifestations. In pure vestibular forms, the diagnosis may be more difficult and is often delayed. The cortical origin of these symptoms will be discussed and compared with the known "vestibular" cortical representations. In addition, the existence of a specific "vestibular epilepsy" has been suggested in some publications. This condition affects young subjects with a frequent family history and most often a benign evolution, raising the possibility of a form of idiopathic epilepsy (Hewett etal., 2011).

Clinical approach to syncope in children

Pediatric syncope is one of the most common neurological problems in the pediatric population in both the office setting and in the emergency department. The abrupt brief loss of consciousness is usually dramatic and alarming to patients, family, onlookers, and providers. The differential diagnosis of syncope is wide but most cases are benign. A comprehensive but focused history and a thorough clinical examination are usually the cornerstones in the diagnosis of high-risk patients. It should be noted that the evaluation of syncope in children is costly and testing provides a low diagnostic yield. This chapter reviews the various types of syncope and provides a succinct clinical approach to the diagnosis, investigation, and management of syncope in children.

Databases for neurogenetics: introduction, overview, and challenges

The importance for research and clinical utility of mutation databases, as well as the issues and difficulties entailed in their construction, is discussed within the Human Variome Project. While general principles and standards can apply to most human diseases, some specific questions arise when dealing with the nature of genetic neurological disorders. So far, publically accessible mutation databases exist for only about half of the genes causing neurogenetic disorders; and a considerable work is clearly still needed to optimize their content. The current landscape, main challenges, some potential solutions, and future perspectives on genetic databases for disorders of the nervous system are reviewed in this special issue of Human Mutation on neurogenetics.

PRRT2 mutations cause benign familial infantile epilepsy and infantile convulsions with choreoathetosis syndrome

Benign familial infantile epilepsy (BFIE) is a self-limited seizure disorder that occurs in infancy and has autosomal-dominant inheritance. We have identified heterozygous mutations in PRRT2, which encodes proline-rich transmembrane protein 2, in 14 of 17 families (82%) affected by BFIE, indicating that PRRT2 mutations are the most frequent cause of this disorder. We also report PRRT2 mutations in five of six (83%) families affected by infantile convulsions and choreoathetosis (ICCA) syndrome, a familial syndrome in which infantile seizures and an adolescent-onset movement disorder, paroxysmal kinesigenic choreoathetosis (PKC), co-occur. These findings show that mutations in PRRT2 cause both epilepsy and a movement disorder. Furthermore, PRRT2 mutations elicit pleiotropy in terms of both age of expression (infancy versus later childhood) and anatomical substrate (cortex versus basal ganglia).

Did Herbert Spencer have reading epilepsy?

Herbert Spencer, the nineteenth-century philosopher, has frequently been dismissed as a "fantastical hypochondriac" (as his most recent biographer, Mark Francis, terms him). Yet he left a record in his Autobiography of symptoms that suggest a very different diagnosis. Abruptly at age 35, he found that the activity of reading, previously indulged in without difficulty, triggered paroxysmal episodes of disturbing "head-sensations" including "giddiness" (so Spencer described them); these severely curtailed his ability to carry out his philosophical studies. Of all possible explanations for such episodes, none seems as likely as reading epilepsy. Enduring preconceptions about Spencer's presumed neurosesmay have kept modern historians from appreciating that Spencer suffered from a legitimate, if esoteric, neurological malady.

A brief primer on sleep for pediatric and child clinical neuropsychologists

Sleep problems are common in the children seen by pediatric and child clinical neuropsychologists, and these problems have the potential to significantly impact the child and his or her family. All are treatable to some degree, and some respond extremely well to existing treatments. This article provides a brief overview of the impact, nature, screening, and treatment for childhood sleep problems, with a particular emphasis on issues relevant to practicing neuropsychologists.

Benign temporo-parieto-occipital junction epilepsy with vestibular disturbance: an underrecognized form of epilepsy?

We describe a series of adolescents and adults who share the electroclinical characteristics of a nonlesional, pharmacoresponsive epilepsy manifesting as prominent vestibular disturbances, suggesting a temporo-parieto-occipital (TPO) junction origin. We retrospectively reviewed a database of consecutive patients referred to the epilepsy clinic over a 10-year period with respect to the following criteria: recurrent episodes of paroxysmal vestibular symptoms, normal MRI, and interictal EEG changes over the posterior regions. Fourteen patients were finally selected (10 males, 4 females). Mean age at onset was 26.5 (range: 12-59). The diagnosis of epilepsy was usually delayed until after cardiology and/or otorhinolaryngology workup. The predominant features on interictal scalp EEGs were abnormalities over the posterior areas. All patients responded well to antiepileptic medication. We propose that although further characterization is needed to label it a syndrome, this underdiagnosed form of epilepsy merits recognition.

PTG depletion removes Lafora bodies and rescues the fatal epilepsy of Lafora disease

Lafora disease is the most common teenage-onset neurodegenerative disease, the main teenage-onset form of progressive myoclonus epilepsy (PME), and one of the severest epilepsies. Pathologically, a starch-like compound, polyglucosan, accumulates in neuronal cell bodies and overtakes neuronal small processes, mainly dendrites. Polyglucosan formation is catalyzed by glycogen synthase, which is activated through dephosphorylation by glycogen-associated protein phosphatase-1 (PP1). Here we remove PTG, one of the proteins that target PP1 to glycogen, from mice with Lafora disease. This results in near-complete disappearance of polyglucosans and in resolution of neurodegeneration and myoclonic epilepsy. This work discloses an entryway to treating this fatal epilepsy and potentially other glycogen storage diseases.

Lafora disease (LD) is a fatal epilepsy that afflicts previously normal teenagers. It is caused by mutations in the EPM2A or EPM2B genes encoding the laforin carbohydrate-binding phosphatase and the malin E3 ubiquitin ligase. LD is the most common neurodegenerative epilepsy of adolescents. Affected children suffer an ordeal lasting 10 years, consisting of escalating seizures, constant body jerking, particularly frightening epileptic visual hallucinations, and later on dementia. They die of massive convulsion. Brain biopsies reveal accumulation of a starch-like compound, polyglucosan, overtaking dendrites and likely causing the disease, and neurodegeneration. Glycogen synthase (GS), the enzyme that forms normal glycogen, is also responsible for synthesizing these polyglucosans. We reasoned that reducing GS activity might prevent polyglucosan formation. Mice deficient of Epm2a replicate LD and are a standard model. Members of our group generated mice deficient of PTG, a protein involved in activating GS. By breeding LD mice with PTG-lacking mice, we generated LD mice lacking the GS-activating effect of PTG. This resulted in a cure. The double knockout mice have almost no polyglucosan, no neurodegeneration, and no seizures. Our work opens an avenue of treatment for this fatal epilepsy, which may also be applicable to other glycogen storage diseases.

Seizure in a nonpredisposed individual induced by single-pulse transcranial magnetic stimulation

Seizure induction is a rare, but serious adverse effect of the otherwise very safe method of transcranial magnetic stimulation (TMS). There are only very few single case reports concerning seizure in single-pulse TMS. All of these reports describe individuals with neurological disorders or epileptogenic medication. To our knowledge, we are the first to describe a healthy subject who developed symptoms of a seizure after single-pulse TMS during motor threshold estimation. This case report provides evidence that single-pulse TMS may provoke a seizure even in the absence of neurological risk factors. Differential diagnoses of a classic neurological seizure, that is, convulsive syncope and psychogenic seizure, are discussed. Neurogenic seizure after TMS and convulsive syncope are the most probable hypotheses, although clear specification of this singular incident remains impossible. Therefore, to minimize the risk for such rare adverse effects, existing and new suggestions are combined to provide reasonable precautions to be taken before and during TMS application.

Treatment of paroxysmal dyskinesias

IMPORTANCE OF THE FIELD

Paroxysmal dyskinesias represent a heterogeneous group of rare diseases sharing characteristics with two important groups of neurological disorders, the movement disorders and the epilepsies. Their common hallmark is the paroxysmal occurrence of dyskinesias including athetosis, ballism, chorea and dystonia. During the last two decades, various genetic abnormalities have been identified thereby providing insight into the underlying pathophysiology and offering therapeutic opportunities for many of these conditions.

AREAS COVERED IN THIS REVIEW

We summarize the diagnostic criteria of idiopathic and symptomatic paroxysmal dyskinesias and describe their therapeutic options. For the preparation of this review article, an extensive literature search was undertaken using PubMed.

WHAT THE READER WILL GAIN

This review provides a practical guide to the diagnosis and treatment of paroxysmal dyskinesias.

TAKE HOME MESSAGE

The mainstay of therapy is carbamazepine for paroxysmal kinesigenic dyskinesias and clonazepam for the nonkinesigenic dyskinesias. In symptomatic paroxysmal dyskinesias, the treatment of the underlying disease will provide best results. The ketogenic diet for patients with paroxysmal exertion-induced dyskinesias is a promising new therapeutic strategy and may not only prevent attacks but also lead to improvement of developmental delay in affected children.

Idiopathic paroxysmal kinesigenic dyskinesia in Malaysia, a multi-racial Southeast Asian country

Paroxysmal kinesigenic dyskinesia is a rare disorder, and there are few reports of Asian patients with this condition. We reviewed the clinical features of all patients with idiopathic paroxysmal kinesigenic dyskinesia (PKD) seen at a major neurological centre in Malaysia. The charts of 11 patients with idiopathic PKD seen between 1995 and 2008 were reviewed retrospectively. The male:female ratio was 9:2. Ten patients were of Chinese ethnicity, and one was Malay. Three patients (from two families) had a family history of PKD. The involuntary movement was dystonia in 73% of patients. In one patient, attacks were precipitated by vestibular stimulation. One patient had generalized epilepsy. Another patient who did not have epilepsy demonstrated epileptiform discharges. Only slightly over one-quarter of patients had a positive family history. Males, and people of Chinese ancestry, seem to be affected more frequently by PKD in certain Asian populations.

Too long or too short? New insights into abnormal cardiac repolarization in people with chronic epilepsy and its potential role in sudden unexpected death

SUMMARY

Sudden unexpected death in epilepsy (SUDEP) is probably caused by periictal cardiorespiratory alterations such as central apnea, bradyarrhythmia, and neurogenic pulmonary edema. These alterations may occur in people with epilepsy and vary in duration and severity. Seizure-related ventricular tachyarrhythmias have also been hypothesized to be involved in SUDEP, but compelling evidence of these, or of predisposition to these, is lacking. Ventricular tachyarrhythmias are facilitated by pathologic cardiac repolarization. Electrocardiography (ECG) indicators of pathologic cardiac repolarization, such as prolongation or shortening of QT intervals as well as increased QT dispersion, are established risk factors for life-threatening tachyarrhythmia and sudden cardiac death (SDC). Abnormalities in cardiac repolarization have recently been described in people with epilepsy. Importantly, periictal ventricular tachycardia and fibrillation have also been reported in the absence of any underlying cardiac disease. Therefore, pathologic cardiac repolarization could promote SCD in people with epilepsy and could be one plausible cause for SUDEP. Herein, we review abnormal cardiac repolarization in people with epilepsy, describe the putative contribution of antiepileptic drugs, and discuss the potential role of pathologic cardiac repolarization in SUDEP. Based on these, measures to reduce the risk of or prevent SUDEP may include antiarrhythmic medication and implantation of cardiac combined pacemaker-defibrillator devices.

A migraine variant with abdominal colic and Alice in Wonderland syndrome: a case report and review

BACKGROUND

Abdominal migraine is a commonly described migraine variant in children and young adults, but associations with Alice in Wonderland syndrome and lilliputian hallucinations are exceptional.

CASE PRESENTATION

A 20 years-old male experienced frequent and prolonged attacks of abdominal colic associated with autonomic manifestations started at the age of ten. At the age of 17, he additionally described prolonged attacks (>or= 7 days) of distortions of shape, size or position of objects or subjects. He said "Quite suddenly, objects appear small and distant (teliopsia) or large and close (peliopsia). I feel as I am getting shorter and smaller "shrinking" and also the size of persons are not longer than my index finger (a lilliputian proportion). Sometimes I see the blind in the window or the television getting up and down, or my leg or arm is swinging. I may hear the voices of people quite loud and close or faint and far. Occasionally, I experience attacks of migrainous headache associated with eye redness, flashes of lights and a feeling of giddiness. I am always conscious to the intangible changes in myself and my environment". There is a strong family history of common migraine. Clinical examination, brain-MRI and EEG were normal. Transcranial magnetic stimulation and evoked potentials revealed enhanced cortical excitability in multiple brain regions. Treatment with valproate resulted in marked improvement of all clinical and neurophysiological abnormalities.

CONCLUSIONS

The association between the two migraine variants (abdominal migraine and Alice in Wonderland Syndrome) might have clinical, pathophysiological and management implications. I think this is the first description in the literature.

Epilepsy in later life

Epilepsy is most likely to develop in later life. The burden of this disorder on health-care resources will rise further as the world's population continues to age. Making a secure diagnosis can be challenging because the clinical manifestations of seizures and the differential diagnoses and causes of epilepsy can be different in older individuals compared with younger individuals. Obtaining a reliable account of the events for accurate assessment is particularly important in guiding the appropriate choice and interpretation of investigations to arrive at the correct diagnosis. In older age, unique pharmacokinetic and pharmacodynamic changes occur. The use and selection of antiepileptic drugs is often further complicated by the presence of comorbidities, polypharmacy, and concomitant functional impairment, but there is a paucity of high-level clinical evidence on the effects of these factors as well as on the choice of treatment in the elderly. A comprehensive model of care should combine expertise in the diagnosis and treatment of epilepsy with effective assessment and management of the psychosocial effects to improve the prognosis in this vulnerable and poorly studied group of patients.

[Is there a bridge between migraine and familial mesial temporal lobe epilepsy?]

Numerous reviews have emphasized the links between certain types of epilepsy and migraine. Historically, Gowers was one of the first, in 1907, to have drawn attention to a possible relationship between migraine headache and epilepsy in a period when no additional examination was available. In the last two decades, progress in molecular biology, electrophysiology, and neuro-imaging has enabled a better approach to the fundamental elements underlying the interrelationship between these two nosological domains. During this same time, a new term "channelopathy" has appeared in the literature. This term groups together affections involving a dysfunction of ion channels. In this article, the links between the different types of migraine and familial mesial temporal lobe epilepsy are illustrated by two case reports. This association does not appear to occur at random but would undoubtedly depend on a common genetic substratum, leading to a direct comorbidity. These occasional recurring symptoms would lie within the framework of a more general concept of "Primary Brain Channelopathies".