The landscape of drug resistant absence seizures in adolescents and adults: Pathophysiology, electroclinical spectrum and treatment options

The persistence of typical absence seizures (AS) in adolescence and adulthood may reduce the quality of life of patients with genetic generalized epilepsies (GGEs). The prevalence of drug resistant AS is probably underestimated in this patient population, and treatment options are relatively scarce. Similarly, atypical absence seizures in developmental and epileptic encephalopathies (DEEs) may be unrecognized, and often persist into adulthood despite improvement of more severe seizures. These two seemingly distant conditions, represented by typical AS in GGE and atypical AS in DEE, share at least partially overlapping pathophysiological and genetic mechanisms, which may be the target of drug and neurostimulation therapies. In addition, some patients with drug-resistant typical AS may present electroclinical features that lie in between the two extremes represented by these generalized forms of epilepsy.

Drug-resistant epilepsy at the age extremes: Disentangling the underlying etiology

The incidence of epilepsy is highest at the extreme age ranges: childhood and elderly age. The most common syndromes in these demographics - self-limited epilepsies of childhood and idiopathic generalized epilepsies in pediatric age, focal epilepsy with structural etiology in older people - are expected to be drug responsive. In this work, we focus on such epilepsy types, overviewing the complex clinical background of unexpected drug-resistance. For self-limited epilepsies of childhood and idiopathic generalized epilepsies, we illustrate drug-resistance resulting from syndrome misinterpretation, reason on possible unexpected courses of epilepsy, and explicate the influence of inappropriate treatments. For elderly-onset epilepsy, we show the challenges in differential diagnosis possibly leading to pseudoresistance and analyze how drug-resistant epilepsy can arise in stroke, neurocognitive disorders, brain tumors, and autoimmune encephalitis. In children and senior people, drug-resistance can be regarded as a hint to review the diagnosis or explore alternative therapeutic strategies. Refractory seizures are not only a therapeutic challenge, but also a cardinal sign not to be overlooked in syndromes commonly deemed to be drug-responsive.

Social cognition in idiopathic generalized epilepsies and potential neuroanatomical correlates

Social cognition allows us to elaborate mental representations of social relationships and use them appropriately in a social environment. One of its main attributes is the so-called Theory of Mind (ToM), which consists of the ability to attribute beliefs, intentions, emotions, and feelings to self and others. Investigating social cognition may help understand the poor social outcome often experienced by persons with Idiopathic Generalized Epilepsies (IGE), who otherwise present with normal intelligence. In recent years, several studies have addressed social cognition in subjects with focal epilepsies, while literature on social cognition in IGE is scarce, and findings are often conflicting. Some studies on samples of patients with mixed IGE showed difficulties in emotion attribution tasks, which were not replicated in a homogeneous population of patients with Juvenile Myoclonic Epilepsy alone. Impairment of higher order social skills, such as those assessed by Strange Stories Test and Faux Pas Tasks, were consistently found by different studies on mixed IGE, suggesting that this may be a more distinctive IGE-associated trait, irrespective of the specific syndrome subtype. Though an interplay between social cognition and executive functions (EF) was suggested by several authors, and their simultaneous impairment was shown in several epilepsy syndromes including IGE, no formal correlations among the two domains were identified in most studies. People with IGE exhibit subtle brain structural alterations in areas potentially involved in sociocognitive functional networks, including mesial prefrontal and temporoparietal cortices, which may relate to impairment in social cognition. Heterogeneity in patient samples, mostly consisting of groups with mixed IGE, and lack of analyses in specific IGE subsyndromes, represent evident limitations of the current literature. Larger studies, focusing on specific subsyndromes and implementing standardized test batteries, will improve our understanding of sociocognitive processing in IGE. Concomitant high-resolution structural and functional neuroimaging may aid the identification of its neural correlates. This article is part of the Special Issue "Epilepsy and social cognition across the lifespan".

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.