Juvenile myoclonic epilepsy: is it an idiopathic epilepsy caused by a malformation of cortical development?

Emotional Word Processing in Patients With Juvenile Myoclonic Epilepsy

Objective

According to Panksepp's hierarchical emotion model, emotion processing relies on three functionally and neuroanatomically distinct levels. These levels comprise subcortical networks (primary level), the limbic system (secondary level), and the neocortex (tertiary level) and are suggested to serve differential emotional processing. We aimed to validate and extend previous evidence of discrete and dimensional emotion processing in patient with juvenile myoclonic epilepsy (JME).

Methods

We recorded brain activity of patients with JME and healthy controls in response to lexical decisions to words reflecting the discrete emotion fear and the affective dimension negativity previously suggested to rely on different brain regions and to reflect different levels of processing. In all study participants, we tested verbal cognitive functions, as well as the relationship of psychiatric conditions, seizure types and duration of epilepsy and emotional word processing.

Results

In support of the hierarchical emotion model, we found an interaction of discrete emotion and affective dimensional processing in the right amygdala likely to reflect secondary level processing. Brain activity related to affective dimensional processing was found in the right inferior frontal gyrus and is suggested to reflect tertiary level processing. Psychiatric conditions, type of seizure nor mono- vs. polytherapy and duration of epilepsy within patients did not have any effect on the processing of emotional words. In addition, no differences in brain activity or response times between patients and controls were observed, despite neuropsychological testing revealed slightly decreased verbal intelligence, verbal fluency and reading speed in patients with JME.

Significance

These results were interpreted to be in line with the hierarchical emotion model and to highlight the amygdala's role in processing biologically relevant stimuli, as well as to suggest a semantic foundation of affective dimensional processing in prefrontal cortex. A lack of differences in brain activity of patients with JME and healthy controls in response to the emotional content of words could point to unaffected implicit emotion processing in patients with JME.

An appraisal of the new operational definition of epilepsy--then and now

The focus to define epilepsy in the newly proposed classification has shifted from the conceptual perspective to practical application thought to better reflect that which is happening to the patient. Within the new definition, a single unprovoked or reflex seizure can be considered as epilepsy if the recurrence risk is similar to that following two unprovoked seizures. Epilepsy is considered to be resolved if the individual had an age-dependent epilepsy syndrome and has passed the applicable age or if the person has remained seizure-free for the last ten years without seizure medications for the last five years. This new operational definition of epilepsy may change the epileptologist's approach regarding when and how long to treat patients with seizures. The new definition also has significant psychosocial and employment-related implications for the patients. With regard to etiology, the terms idiopathic, symptomatic, and cryptogenic have been replaced by genetic, structural/metabolic, and unknown. This reflects a better understanding of the underlying cause of epilepsy based on genetic tests and better neuroimaging. The terms 'simple partial' and 'complex partial' seizures have been replaced by 'focal motor/sensory' and 'focal dyscognitive' seizures, thereby ending the ambiguity associated with the former terms and the difficulty encountered with definitions of altered states of consciousness. These changes, reflective of a better insight into the pathogenesis of seizures and epilepsy, are expected to be more pragmatic and assist when managing patients with epilepsy.

Regional increase of cerebral cortex thickness in juvenile myoclonic epilepsy

The goal of this study was to characterize cerebral cortex thickness patterns in juvenile myoclonic epilepsy (JME). Surface-based morphometry (SBM) was applied to process brain magnetic resonance images acquired from 24 patients with JME and 40 healthy controls and quantify cerebral cortex thickness. Differences in cortical thickness between patients and controls were determined using generalized linear model (covariates: age and gender). In patients with JME, thickness increase was detected bilaterally within localized regions in the orbitofrontal and mesial frontal cortices. Such thickness patterns coexisted with significant bilateral reduction in thalamic volume. These findings confirm that the underlying mechanisms in JME are related to aberrant corticothalamic structure and indicate that frontal cortex abnormalities are possibly linked to regional increase in cerebral cortical thickness.

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.

New concepts in classification of the epilepsies: entering the 21st century

Concepts and terminology for classifying seizures and epilepsies have, until recently, rested on ideas developed nearly a century ago. In order for clinical epilepsy and practice to benefit fully from the major technological and scientific advances of the last several years, advances that are revolutionizing our understanding and treatment of the epilepsies, it is necessary to break with the older vocabulary and approaches to classifying epilepsies and seizures. The Commission on Classification and Terminology made specific recommendations to move this process along and ensure that classification will reflect the best knowledge, will not be arbitrary, and will ultimately serve the purpose of improving clinical practice as well as research on many levels. The recommendations include new terms and concepts for etiology and seizure types as well as abandoning the 1989 classification structure and replacing it instead with a flexible multidimensional approach in which the most relevant features for a specific purpose can be emphasized. This is not a finished product and will take yet more time to achieve. Waiting any longer, however, would be a disservice to patient care and will continue the longstanding frustrations with the earlier system which, at this point in time, can be viewed as both antiquated and arbitrary.