Routine and sleep EEG: Minimum recording standards of the International Federation of Clinical Neurophysiology and the International League Against Epilepsy

This article provides recommendations on the minimum standards for recording routine ("standard") and sleep electroencephalography (EEG). The joint working group of the International Federation of Clinical Neurophysiology (IFCN) and the International League Against Epilepsy (ILAE) developed the standards according to the methodology suggested for epilepsy-related clinical practice guidelines by the Epilepsy Guidelines Working Group. We reviewed the published evidence using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The quality of evidence for sleep induction methods was assessed by the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) method. A tool for Quality Assessment of Diagnostic Studies (QUADAS-2) was used to assess the risk of bias in technical and methodological studies. Where high-quality published evidence was lacking, we used modified Delphi technique to reach expert consensus. The GRADE system was used to formulate the recommendations. The quality of evidence was low or moderate. We formulated 16 consensus-based recommendations for minimum standards for recording routine and sleep EEG. The recommendations comprise the following aspects: indications, technical standards, recording duration, sleep induction, and provocative methods.

Routine and sleep EEG: Minimum recording standards of the International Federation of Clinical Neurophysiology and the International League Against Epilepsy

This article provides recommendations on the minimum standards for recording routine ("standard") and sleep electroencephalography (EEG). The joint working group of the International Federation of Clinical Neurophysiology (IFCN) and the International League Against Epilepsy (ILAE) developed the standards according to the methodology suggested for epilepsy-related clinical practice guidelines by the Epilepsy Guidelines Working Group. We reviewed the published evidence using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The quality of evidence for sleep induction methods was assessed by the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) method. A tool for Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess the risk of bias in technical and methodological studies. Where high-quality published evidence was lacking, we used modified Delphi technique to reach expert consensus. The GRADE system was used to formulate the recommendations. The quality of evidence was low or moderate. We formulated 16 consensus-based recommendations for minimum standards for recording routine and sleep EEG. The recommendations comprise the following aspects: indications, technical standards, recording duration, sleep induction, and provocative methods.

Myoclonus as a Manifestation of Reflex Seizures

SUMMARY

Myoclonus is a motor symptom commonly associated with reflex seizures in people with idiopathic generalized epilepsies. The most frequently observed triggers of myoclonus are related to visual stimuli, including flashing lights or patterns; nonetheless, myoclonus can also be activated by movement, speech or reading, calculations, and praxis. Reflex myoclonic seizures may be the hallmark of a reflex epilepsy, but it may lead to the diagnosis of generalized epilepsy syndromes. In the setting of idiopathic generalized epilepsies, reflex myoclonus can persist despite optimal medical therapies and may be a marker for active, even medically intractable, epilepsy. In this article, the clinical significance, diagnosis, and treatment of myoclonus, associated with visual stimulation, movement, and praxis, will be reviewed.

Genetic generalized epilepsies in adults - challenging assumptions and dogmas

Genetic generalized epilepsy (GGE) syndromes start during childhood or adolescence, and four commonly persist into adulthood, making up 15-20% of all cases of epilepsy in adults. These four GGE syndromes are childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy and epilepsy with generalized tonic-clonic seizures alone. However, in ~20% of patients with GGE, characteristics of more than one syndrome are present. Novel insights into the genetic aetiology, comorbidities and prognosis of the GGE syndromes have emerged and challenge traditional concepts about these conditions. Evidence has shown that the mode of inheritance in GGE is mostly polygenic. Neuropsychological and imaging studies indicate similar abnormalities in unaffected relatives of patients with GGE, supporting the concept that underlying alterations in bilateral frontothalamocortical networks are genetically determined. Contrary to popular belief, first-line anti-seizure medication often fails to provide seizure freedom in combination with good tolerability. Nevertheless, long-term follow-up studies have shown that with advancing age, many patients can discontinue their anti-seizure medication without seizure relapses. Several outcome predictors have been identified, but prognosis across the syndromes is more homogeneous than previously assumed. Overall, overlap in pathophysiology, seizure types, treatment responses and outcomes support the idea that GGEs are not separate nosological entities but represent a neurobiological continuum.

The Effect of Cognitive Tasks During Electroencephalography Recording in Patients With Reflex Seizures

OBJECTIVE

We aimed to research the effect of cognitive tasks on interictal electroencephalographic (EEG) recordings in patients with epilepsy who had reported cognitive functions as a seizure trigger. We investigated the usefulness of cognitive function tasks as a method of activation in standard-awake EEG in daily practice.

METHODS

Standard-awake EEG with cognitive activation tasks consisting of verbal and arithmetic tasks was administered to 35 (11.7%) of 299 patients with epilepsy who reported cognitive functions as a reflex seizure stimulus. During the background EEG, patients were divided into 2 groups: group 1 (17 patients) with interictal epileptiform discharges (IEDs), and group 2 (18 patients) without IEDs.

RESULTS

IEDs were activated by a verbal task in 11.4% of patients and by an arithmetic task in 5.7%. All activated patients were in the genetic/idiopathic generalized epilepsy (IGE) group. In group 1, IEDs were activated in 17.6% of patients by a verbal task and in 5.9% by an arithmetic task. Both verbal and arithmetic tasks showed provocative effect in one patient in group 2. Hyperventilation was the most effective activation method, followed by cognitive activation tasks and photic stimulation. The provocative effects of verbal and arithmetic tasks were comparable to those of photic stimulation.

CONCLUSION

Cognitive tasks might activate the IEDs in patients reporting cognitive functions as a seizure trigger, particularly in IGE. Brief and standardized cognitive activation tasks should be developed and applied as a method of activation during standard-awake EEG recordings to increase the diagnostic yield of EEG.

Minimum standards for inpatient long-term video-EEG monitoring: A clinical practice guideline of the international league against epilepsy and international federation of clinical neurophysiology

The objective of this clinical practice guideline is to provide recommendations on the indications and minimum standards for inpatient long-term video-electroencephalographic monitoring (LTVEM). The Working Group of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology develop guidelines aligned with the Epilepsy Guidelines Task Force. We reviewed published evidence using The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. We found limited high-level evidence aimed at specific aspects of diagnosis for LTVEM performed to evaluate patients with seizures and nonepileptic events (see Table S1). For classification of evidence, we used the Clinical Practice Guideline Process Manual of the American Academy of Neurology. We formulated recommendations for the indications, technical requirements, and essential practice elements of LTVEM to derive minimum standards used in the evaluation of patients with suspected epilepsy using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). Further research is needed to obtain evidence about long-term outcome effects of LTVEM and establish its clinical utility.

Minimum standards for inpatient long-term video-electroencephalographic monitoring: A clinical practice guideline of the International League Against Epilepsy and International Federation of Clinical Neurophysiology

The objective of this clinical practice guideline is to provide recommendations on the indications and minimum standards for inpatient long-term video-electroencephalographic monitoring (LTVEM). The Working Group of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology develop guidelines aligned with the Epilepsy Guidelines Task Force. We reviewed published evidence using the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) statement. We found limited high-level evidence aimed at specific aspects of diagnosis for LTVEM performed to evaluate patients with seizures and nonepileptic events. For classification of evidence, we used the Clinical Practice Guideline Process Manual of the American Academy of Neurology. We formulated recommendations for the indications, technical requirements, and essential practice elements of LTVEM to derive minimum standards used in the evaluation of patients with suspected epilepsy using GRADE (Grading of Recommendations Assessment, Development, and Evaluation). Further research is needed to obtain evidence about long-term outcome effects of LTVEM and to establish its clinical utility.

Let there be light: Inhibitory effect of photic stimulation on spike frequency in patients with mesial temporal lobe epilepsy with hippocampal sclerosis

Inhibition of epileptic discharges and seizures by sensory stimuli is an interesting phenomenon, but highly understudied. Here, we aimed to investigate the modulation of epileptiform discharges in patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS) via photic stimulation (PS), based on a hypothesis that light stimulation may activate thalamocortical networks limiting the propagation of interictal epileptiform discharges. In order to do so, all EEGs performed in patients diagnosed with MTLE-HS were reviewed to include available recordings with definite epileptiform abnormalities. These were reevaluated by two clinical neurophysiologists independently, and spikes were counted in a blinded manner to calculate spike index (SI) (spikes per minute-pm) for baseline EEG, hyperventilation (HV), and PS periods. Our final study group consisted of 30 MTLE-HS patients with a mean age of 34.5 (±12.5) years. Mean seizure frequency was 38.1 per year (±46.6), and the mean disease duration was 16.2 years (±12.1). Mean SI during baseline was calculated as 1.17 pm (±1.4), during HV 2.1 pm (±2.8) and during PS 0.8 pm (±2.5). As a result, SI was significantly lower during PS compared to baseline (p = 0.001). Our findings suggest that PS has a remarkable inhibitory effect on epileptiform discharges in MTLE-HS patients, indicating the need for further prospective investigations for clinical translation.

Ambulatory EEG Usefulness in Epilepsy Management

SUMMARY

Long-term video-EEG monitoring has been the gold standard for diagnosis of epileptic and nonepileptic events. Medication changes, safety, and a lack of recording EEG in one's habitual environment may interfere with diagnostic representation and subsequently affect management. Some spells defy standard EEG because of ultradian and circadian times of occurrence, manifest nocturnal expression of epileptiform activity, and require classification for clarifying diagnostic input to identify optimal treatment. Some patients may be unaware of seizures, have frequent events, or subclinical seizures that require quantification before optimal management. The influence on antiseizure drug management and clinical drug research can be enlightened by long-term outpatient ambulatory EEG monitoring. With recent governmental shifts to focus on mobile health, ambulatory EEG monitoring has grown beyond diagnostic capabilities to target the dynamic effects of medical and nonmedical treatment for patients with epilepsy in their natural environment. Furthermore, newer applications in ambulatory monitoring include additional physiologic parameters (e.g., sleep, detection of myogenic signals, etc.) and extend treatment relevance to patients beyond seizure reduction alone addressing comorbid conditions. It is with this focus in mind that we direct our discussion on the present and future aspects of using ambulatory EEG monitoring in the treatment of patients with epilepsy.

Location-specific reflex epilepsy: a novel reflex epilepsy phenotype

Reflex epilepsies are rare syndromes where seizures are triggered by particular stimuli or activities that may be motor, sensory or cognitive in nature. Triggers are diverse, may be extrinsic or intrinsic in nature and heterogeneous phenotypes have been described over the years. We give an account of a case of location-specific reflex epilepsy which we suggest is a novel reflex epilepsy phenotype relating to higher cortical function (HCF), and review the literature in relation to features of HCF reflex epilepsies described to date.

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Reflex seizures occur in a range of epilepsy syndromes.

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We describe a novel phenotype of location-specific reflex epilepsy associated with focal electrographic discharges.

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Higher cortical processes relating to being present in a particular location could serve as a trigger in reflex epilepsy.

Motor hyperactivation during cognitive tasks: An endophenotype of juvenile myoclonic epilepsy

OBJECTIVE

Juvenile myoclonic epilepsy (JME) is the most common genetic generalized epilepsy syndrome. Myoclonus may relate to motor system hyperexcitability and can be provoked by cognitive activities. To aid genetic mapping in complex neuropsychiatric disorders, recent research has utilized imaging intermediate phenotypes (endophenotypes). Here, we aimed to (a) characterize activation profiles of the motor system during different cognitive tasks in patients with JME and their unaffected siblings, and (b) validate those as endophenotypes of JME.

METHODS

This prospective cross-sectional investigation included 32 patients with JME, 12 unaffected siblings, and 26 controls, comparable for age, sex, handedness, language laterality, neuropsychological performance, and anxiety and depression scores. We investigated patterns of motor system activation during episodic memory encoding and verb generation functional magnetic resonance imaging (fMRI) tasks.

RESULTS

During both tasks, patients and unaffected siblings showed increased activation of motor system areas compared to controls. Effects were more prominent during memory encoding, which entailed hand motion via joystick responses. Subgroup analyses identified stronger activation of the motor cortex in JME patients with ongoing seizures compared to seizure-free patients. Receiver-operating characteristic curves, based on measures of motor activation, accurately discriminated both patients with JME and their siblings from healthy controls (area under the curve: 0.75 and 0.77, for JME and a combined patient-sibling group against controls, respectively; P < .005).

SIGNIFICANCE

Motor system hyperactivation represents a cognitive, domain-independent endophenotype of JME. We propose measures of motor system activation as quantitative traits for future genetic imaging studies in this syndrome.

Subtle Brain Developmental Abnormalities in the Pathogenesis of Juvenile Myoclonic Epilepsy

Juvenile myoclonic epilepsy (JME), a lifelong disorder that starts during adolescence, is the most common of genetic generalized epilepsy syndromes. JME is characterized by awakening myoclonic jerks and myoclonic-tonic-clonic (m-t-c) grand mal convulsions. Unfortunately, one third of JME patients have drug refractory m-t-c convulsions and these recur in 70-80% who attempt to stop antiepileptic drugs (AEDs). Behavioral studies documented impulsivity, but also impairment of executive functions relying on organization and feedback, which points to prefrontal lobe dysfunction. Quantitative voxel-based morphometry (VBM) revealed abnormalities of gray matter (GM) volumes in cortical (frontal and parietal) and subcortical structures (thalamus, putamen, and hippocampus). Proton magnetic resonance spectroscopy (MRS) found evidence of dysfunction of thalamic neurons. White matter (WM) integrity was disrupted in corpus callosum and frontal WM tracts. Magnetic resonance imaging (MRI) further unveiled anomalies in both GM and WM structures that were already present at the time of seizure onset. Aberrant growth trajectories of brain development occurred during the first 2 years of JME diagnosis. Because of genetic origin, disease causing variants were sought, first by positional cloning, and most recently, by next generation sequencing. To date, only six genes harboring pathogenic variants (GABRA1, GABRD, EFHC1, BRD2, CASR, and ICK) with Mendelian and complex inheritance and covering a limited proportion of the world population, are considered as major susceptibility alleles for JME. Evidence on the cellular role, developmental and cell-type expression profiles of these six diverse JME genes, point to their pathogenic variants driving the first steps of brain development when cell division, expansion, axial, and tangential migration of progenitor cells (including interneuron cortical progenitors) sculpture subtle alterations in brain networks and microcircuits during development. These alterations may explain "microdysgenesis" neuropathology, impulsivity, executive dysfunctions, EEG polyspike waves, and awakening m-t-c convulsions observed in JME patients.

Juvenile myoclonic epilepsy and sleep

Juvenile myoclonic epilepsy (JME) is a sleep-related epilepsy syndrome, and only a few studies have addressed the relationship between JME and sleep disorders. In this review, the sleep characteristics of patients with JME were summarized based on the features of circadian rhythm, the possible cause of the early morning seizures, the common subjective and objective sleep disorders, the alterations in sleep architecture, and the effect of sleep deprivation and sodium valproate (VPA). The aims of this study were to summarize the interaction between JME and sleep, to reveal JME sleep characteristics, to encourage clinicians to focus on JME and sleep, to heighten the positive diagnosis rate, to guide the treatment, to improve the prognosis, and to enhance the daily life quality of patients with JME. At the same time, this study aimed to present existing controversies, in order to necessitate further studies.

Reflex epileptic mechanisms in humans: Lessons about natural ictogenesis

The definition of reflex epileptic seizures is that specific seizure types can be triggered by certain sensory or cognitive stimuli. Simple triggers are sensory (most often visual, more rarely tactile or proprioceptive; simple audiogenic triggers in humans are practically nonexistent) and act within seconds, whereas complex triggers like praxis, reading and talking, and music are mostly cognitive and work within minutes. The constant relation between a qualitatively, often even quantitatively, well-defined stimulus and a specific epileptic response provides unique possibilities to investigate seizure generation in natural human epilepsies. For several reflex epileptic mechanisms (REMs), this has been done. Reflex epileptic mechanisms have been reported less often in focal lesional epilepsies than in idiopathic "generalized" epilepsies (IGEs) which are primarily genetically determined. The key syndrome of IGE is juvenile myoclonic epilepsy (JME), where more than half of the patients present reflex epileptic traits (photosensitivity, eye closure sensitivity, praxis induction, and language-induced orofacial reflex myocloni). Findings with multimodal investigations of cerebral function concur to indicate that ictogenic mechanisms in IGEs largely (ab)use preexisting functional anatomic networks (CNS subsystems) normally serving highly complex physiological functions (e.g., deliberate complex actions and linguistic communication) which supports the concept of system epilepsy. Whereas REMs in IGEs, thus, are primarily function-related, in focal epilepsies, they are primarily localization-related. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Efficacy and safety of a video-EEG protocol for genetic generalized epilepsies

INTRODUCTION

Video-EEG has been used to characterize genetic generalized epilepsies (GGE). For best performance, sleep recording, photic stimulation, hyperventilation, and neuropsychological protocols are added to the monitoring. However, risks and benefits of these video-EEG protocols are not well established. The aim of this study was to analyze the efficacy and safety of a video-EEG neuropsychological protocol (VNPP) tailored for GGE and compare its value with that of routine EEG (R-EEG).

METHODS

We reviewed the VNPP and R-EEG of patients with GGE. We considered confirmation of the clinical suspicion of a GGE syndrome and characterization of reflex traits as benefits; and falls, injuries, psychiatric and behavioral changes, generalized tonic-clonic (GTC) seizures, and status epilepticus (SE) as the main risks of the VNPP.

RESULTS

The VNPPs of 113 patients were analyzed. The most common epileptic syndrome was juvenile myoclonic epilepsy (85.8%). The protocol confirmed a GGE syndrome in 97 patients and 62 had seizures. Sleep recording had a provocative effect in 51.2% of patients. The second task that showed highest efficacy was praxis (39.3%) followed by hyperventilation (31.3%). Among the risks, 1.8% had GTC seizures and another 1.8%, SE. Eighteen percent of patients had persistently normal R-EEG, 72.2% of them had discharges during VNPP. Generalized tonic-clonic seizures, myoclonic status epilepticus, and repeated seizures were the main risks of VNPP present in 6 (5.31%) patients while there were no complications during R-EEG.

CONCLUSIONS

The VNPP in GGE is a useful tool in diagnosis and characterization of reflex traits, and is a safe procedure. Its use might preclude multiple R-EEG exams.

Expression of praxis induction on cortical excitability in juvenile myoclonic epilepsy

OBJECTIVE

This study aimed to evaluate the effects of praxis induction on sensorimotor cortical and transcallosal excitability in juvenile myoclonic epilepsy (JME).

METHODS

A total of 36 subjects (18-62years) were included. The JME group was screened by video-electroencephalography neuropsychological protocol and divided into JME without praxis induction [JME-WI (n=12)], JME with praxis-induced seizures or epileptiform discharges [JME-PI (n=10)], and healthy controls (n=14). Motor and somatosensory cortical excitability and transcallosal pathways were evaluated through single-pulse transcranial magnetic stimulation (sTMS) and somatosensory evoked potentials (SEPs).

RESULTS

Motor and transcallosal excitabilities tested with sTMS were not different in the motor-dominant or non-dominant hemisphere among groups. Significant differences were found in cortical SEP amplitudes in the P27 component of the non-dominant hemisphere (p=0.03, Cohen's d=0.98), N35 in the dominant hemisphere (p=0.04, Cohen's d=0.96), and P27-35 interpeak amplitude in both somatosensory cortices of the JME-PI group (p=0.03, Cohen's d=0.96; p=0.02, Cohen's d=1.05) when compared with healthy controls. Giant SEPs were observed in two (16.7%) and five (50%) patients of the JME-WI and JME-PI groups, respectively. Cortical latencies did not reveal differences.

CONCLUSIONS

Praxis induction was associated with enhanced excitability in the somatosensory cortex of JME patients.

SIGNIFICANCE

These findings may help clarifying the less favorable therapeutic response in the JME-PI group and indicate identifying praxis induction as an important determinant in differentiating between JME patients.

Reflex seizures, traits, and epilepsies: from physiology to pathology

Epileptic seizures are generally unpredictable and arise spontaneously. Patients often report non-specific triggers such as stress or sleep deprivation, but only rarely do seizures occur as a reflex event, in which they are objectively and consistently modulated, precipitated, or inhibited by external sensory stimuli or specific cognitive processes. The seizures triggered by such stimuli and processes in susceptible individuals can have different latencies. Once seizure-suppressing mechanisms fail and a critical mass (the so-called tipping point) of cortical activation is reached, reflex seizures stereotypically manifest with common motor features independent of the physiological network involved. The complexity of stimuli increases from simple sensory to complex cognitive-emotional with increasing age of onset. The topography of physiological networks involved follows the posterior-to-anterior trajectory of brain development, reflecting age-related changes in brain excitability. Reflex seizures and traits probably represent the extremes of a continuum, and understanding of their underlying mechanisms might help to elucidate the transition of normal physiological function to paroxysmal epileptic activity.

EEG activation by neuropsychological tasks in idiopathic generalized epilepsy of adolescence

THE AIM OF THE STUDY

To evaluate the effects of neuropsychological activation (NPA) tasks on epileptiform discharges in adolescents with idiopathic generalized epilepsy (IGE) and their possible relationship to clinical epilepsy-related factors, also to compare the effects of the NPA to the habitual methods of electroencephalographic (EEG) activation.

METHODS/SUBJECTS

Fifty-nine patients with IGE aged 14-17 years underwent baseline video-EEG recording with habitual activation procedures followed by NPA tasks, and sleep EEG after sleep deprivation on the next day.

RESULTS

At least one task of NPA showed provocative effect in 18.6% of cases. There was no difference between the provocative effects of action-programming and thinking NPA task groups as well as among individual NPA tasks. The provocative effects of NPA tasks were more prevalent in photosensitive cases, especially the tasks of action-programming type (p=0.04). The provocative NPA effects showed no relationship to gender, age, age at seizure onset, duration of epilepsy, treatment status, presence of myoclonias, recent generalized tonic-clonic seizures, family history of epilepsy. The provocative effects of NPA were comparable to those of hyperventilation (23.7%) and intermittent light stimulation (30.5%) (p>0.05).

CONCLUSIONS

Although the provocative effects NPA tasks on epileptiform discharges on EEG did not outweigh the effects of the habitual activation procedures, NPA activation might be helpful as an additional diagnostic tool in adolescents with IGE in selected cases when routine EEG is not informative enough or when sleep EEG is readily unavailable, also in photosensitive cases. It may also help in providing advice for patients on safety issues.

Motor co-activation in siblings of patients with juvenile myoclonic epilepsy: an imaging endophenotype?

In juvenile myoclonic epilepsy (JME), myoclonic jerks are often triggered by cognitive effort. Wandschneider et al. report co-activation of the motor and prefrontal cognitive networks in unaffected siblings, similar to that previously reported in patients themselves. This co-activation could constitute a heritable marker for further genetic studies of JME.

Juvenile myoclonic epilepsy is a heritable idiopathic generalized epilepsy syndrome, characterized by myoclonic jerks and frequently triggered by cognitive effort. Impairment of frontal lobe cognitive functions has been reported in patients with juvenile myoclonic epilepsy and their unaffected siblings. In a recent functional magnetic resonance imaging study we reported abnormal co-activation of the motor cortex and increased functional connectivity between the motor system and prefrontal cognitive networks during a working memory paradigm, providing an underlying mechanism for cognitively triggered jerks. In this study, we used the same task in 15 unaffected siblings (10 female; age range 18–65 years, median 40) of 11 of those patients with juvenile myoclonic epilepsy (six female; age range 22–54 years, median 35) and compared functional magnetic resonance imaging activations with 20 age- and gender-matched healthy control subjects (12 female; age range 23–46 years, median 30.5). Unaffected siblings showed abnormal primary motor cortex and supplementary motor area co-activation with increasing cognitive load, as well as increased task-related functional connectivity between motor and prefrontal cognitive networks, with a similar pattern to patients (P < 0.001 uncorrected; 20-voxel threshold extent). This finding in unaffected siblings suggests that altered motor system activation and functional connectivity is not medication- or seizure-related, but represents a potential underlying mechanism for impairment of frontal lobe functions in both patients and siblings, and so constitutes an endophenotype of juvenile myoclonic epilepsy.

Praxis induction. Definition, relation to epilepsy syndromes, nosological and prognostic significance. A focused review

PURPOSE

There is increasing awareness that reflex epileptic mechanisms provide unique insight into ictogenesis in human epilepsies. Several of the described triggers have in common that they imply complex visuomotor coordination and decision-making; they are today regarded as variations of one principle, i.e. praxis induction (PI). This focused review considers PI from the aspects of history and delineation, clinical and electroencephalographic presentation, syndromatic relations, prevalence, mechanisms of ictogenesis and nosological implications, treatment and prognosis.

METHODS

We reviewed a series of published articles and case reports on PI in order to clarify clinical and electroencephalographic findings, treatment and outcome.

RESULTS

Findings of both induction and inhibition by the same stimuli suggest widening the reflex epilepsy concept into a broader one of epilepsies with exogenous modification of ictogenesis. PI is closely related to juvenile myoclonic epilepsy (JME) where hyperexcitability and hyperconnectivity of the entire network of visuomotor coordination seem to provide the precondition for eliciting reflex myocloni in the musculature active in the precipitating task.

CONCLUSION

The conclusions on ictogenesis derived from PI support the concept of JME as a system disorder of the brain.

Chronodependency and provocative factors in juvenile myoclonic epilepsy

In juvenile myoclonic epilepsy (JME), occurrence of seizures and epileptiform EEG discharges is influenced by internal and external factors. The most important internal factor is the chronodependency: the occurrence of myoclonic jerks in the early morning is one of the hallmarks of JME. Approximately two-thirds of the patients with JME report that seizures are provoked by a variety of general factors like stress, fatigue, fever, and sleep and more specific precipitants like flashing sunlight, music, reading, thinking, and excess alcohol. The prevalence rate of photosensitivity (photoparoxysmal EEG response) in patients with JME ranges from 8 to 90%; it is seen more often in females and adolescents and depends on drug use. Since both JME and photosensitivity are connected with generalized types of epilepsy and myoclonus, the two traits are comorbid for that reason. Epileptiform EEG discharges can be provoked by other activation methods: sleep, hyperventilation, and specific cognitive tasks. Attention seems to have a non-specific, inhibitory effect of the epileptiform discharges. Hyperventilation can induce absence seizures in patients with JME, while cognitive tasks are efficient in precipitating myoclonic seizures. This article is part of a supplemental special issue entitled Juvenile Myoclonic Epilepsy: What is it Really?

Personality traits in juvenile myoclonic epilepsy: evidence of cortical abnormalities from a surface morphometry study

Cluster B personality disorders (PD), characterized as emotional instability, immaturity, lack of discipline, and rapid mood changes, have been observed among patients with juvenile myoclonic epilepsy (JME) and have been associated with a worse seizure outcome. Proper understanding of the neurobiology of PD associated with JME could contribute to understanding the basis for earlier and more effective interventions. In the present study, volumetric and geometric features of cortical structure were assessed through an automated cortical surface reconstruction method aiming to verify possible structural cortical alterations among patients with JME. Twenty-two patients with JME with cluster B PD, 44 patients with JME without psychiatric disorders, and 23 healthy controls were submitted to a psychiatric evaluation through SCID I and SCID II and to an MRI scan. Significant cortical alterations in mesiofrontal and frontobasal regions, as well as in other limbic and paralimbic regions, were observed mainly in patients with JME with PD. The present study adds evidence to the hypothesis of frontal and limbic involvement in the pathophysiology of cluster B PD in JME, regions linked to mood and affective regulation, as well as to impulsivity and social behavior. Moreover, a multidimensional pattern of frontal, limbic, and paralimbic changes was observed through a method of structural analysis which offers different and simultaneous geometric features, allowing the elaboration of important pathophysiologic insights about cluster B PD in JME.

Frontal lobe function and structure in juvenile myoclonic epilepsy: a comprehensive review of neuropsychological and imaging data

Juvenile myoclonic epilepsy is the most common idiopathic epilepsy syndrome and is considered a benign seizure disorder that responds well to antiepileptic drug treatment, in particular sodium valproate. By definition, routine brain imaging shows no abnormalities, but advanced imaging studies have identified functional and structural abnormalities in the frontal cortex and thalamus. Neuropsychological studies revealed subtle cognitive deficits in patients with JME, mainly implicating the frontal lobes. These findings are in keeping with anecdotal reports of behavioral problems in JME. Cognitive dysfunction in otherwise healthy siblings of patients with JME and a high heritability support the concept of a genetically determined thalamo-frontocortical network dysfunction, accounting for the cognitive impairment and cognitively triggered "motor seizures."

Reflex epilepsy induced by playing Go-stop or Baduk games

PURPOSE

Seizures can be triggered by complex mental activities. The aim of this study was to investigate the clinical characteristics of reflex epilepsy induced by playing Go-stop or Baduk games.

METHODS

The study comprised 11 patients with this type of reflex epilepsy identified from our patient database. We collected data on clinical features, EEG, and brain MRI as well as seizure outcomes.

RESULTS

The patients had a late age of onset (range, 43-65 years, except for one patient with an age of onset of 11 years). An MRI abnormality and interictal EEG abnormalities were found in one patient respectively. The seizures exhibited diverse semiological features suggesting a focal or generalized onset. No myoclonic seizures were observed. Individualized strategies such as avoiding the precipitating game or reducing exposure to the stimulus were most effective in preventing the seizures.

CONCLUSION

The pathophysiological mechanisms underlying Go-stop- or Baduk-induced seizures may be different from other cognition-associated reflex epileptic phenomena. This type of reflex epilepsy may be a heterogeneous syndrome manifesting in a range of diverse semiological features.

Music and epilepsy: a critical review

The effect of music on patients with epileptic seizures is complex and at present poorly understood. Clinical studies suggest that the processing of music within the human brain involves numerous cortical areas, extending beyond Heschl's gyrus and working within connected networks. These networks could be recruited during a seizure manifesting as musical phenomena. Similarly, if certain areas within the network are hyperexcitable, then there is a potential that particular sounds or certain music could act as epileptogenic triggers. This occurs in the case of musicogenic epilepsy, whereby seizures are triggered by music. Although it appears that this condition is rare, the exact prevalence is unknown, as often patients do not implicate music as an epileptogenic trigger and routine electroencephalography does not use sound in seizure provocation. Music therapy for refractory epilepsy remains controversial, and further research is needed to explore the potential anticonvulsant role of music. Dopaminergic system modulation and the ambivalent action of cognitive and sensory input in ictogenesis may provide possible theories for the dichotomous proconvulsant and anticonvulsant role of music in epilepsy. The effect of antiepileptic drugs and surgery on musicality should not be underestimated. Altered pitch perception in relation to carbamazepine is rare, but health care professionals should discuss this risk or consider alternative medication particularly if the patient is a professional musician or native-born Japanese. Studies observing the effect of epilepsy surgery on musicality suggest a risk with right temporal lobectomy, although the extent of this risk and correlation to size and area of resection need further delineation. This potential risk may bring into question whether tests on musical perception and memory should form part of the preoperative neuropsychological workup for patients embarking on surgery, particularly that of the right temporal lobe.

Motor system hyperconnectivity in juvenile myoclonic epilepsy: a cognitive functional magnetic resonance imaging study

Juvenile myoclonic epilepsy is the most frequent idiopathic generalized epilepsy syndrome. It is characterized by predominant myoclonic jerks of upper limbs, often provoked by cognitive activities, and typically responsive to treatment with sodium valproate. Neurophysiological, neuropsychological and imaging studies in juvenile myoclonic epilepsy have consistently pointed towards subtle abnormalities in the medial frontal lobes. Using functional magnetic resonance imaging with an executive frontal lobe paradigm, we investigated cortical activation patterns and interaction between cortical regions in 30 patients with juvenile myoclonic epilepsy and 26 healthy controls. With increasing cognitive demand, patients showed increasing coactivation of the primary motor cortex and supplementary motor area. This effect was stronger in patients still suffering from seizures, and was not seen in healthy controls. Patients with juvenile myoclonic epilepsy showed increased functional connectivity between the motor system and frontoparietal cognitive networks. Furthermore, we found impaired deactivation of the default mode network during cognitive tasks with persistent activation in medial frontal and central regions in patients. Coactivation in the motor cortex and supplementary motor area with increasing cognitive load and increased functional coupling between the motor system and cognitive networks provide an explanation how cognitive effort can cause myoclonic jerks in juvenile myoclonic epilepsy. The supplementary motor area represents the anatomical link between these two functional systems, and our findings may be the functional correlate of previously described structural abnormalities in the medial frontal lobe in juvenile myoclonic epilepsy.

The slow-wave component of the interictal epileptiform EEG discharges

The interictal epileptiform discharges (IEDs) consist of a fast component (FC; spike or sharp-wave) followed by a slow-wave component (SC). Our purpose was to assess the intra-individual variance, the diagnostic significance and the effect of sleep on the SC. Ninety-nine EEG recordings from 50 consecutive patients with IEDs were analysed. We measured the duration (ms) of the SC (SC-duration), while the amplitude of the SC was divided by the amplitude of the FC yielding a normalized value (SC/FC amplitude-ratio). Intra-individual, intra- and inter-recording coefficients of variation (CV) were calculated for the SC-duration and SC/FC amplitude-ratio. The correlation with the diagnosis, and the effect of sleep was analysed. The SC-duration and the SC/FC amplitude-ratio had low CV (<27%). The SC-duration was not correlated with the diagnosis. The SC/FC amplitude-ratio was significantly higher in the patients with generalized epilepsies as compared with the localization-related ones, and it was higher in the patients with idiopathic epilepsies as compared with the symptomatic ones. These predictors were independent. The SC/FC amplitude-ratio of the patients with idiopathic epilepsy increased significantly during sleep. We conclude that the SC-duration and SC/FC amplitude-ratio are stable parameters. The amplitude of the SC in relation to the fast component is larger in patients with generalized and idiopathic epilepsies, suggesting higher degree of cortical inhibition in these patients, possibly corresponding to specific protective mechanisms.