Semiology and Epileptic Networks

Neural correlates of rhythmic rocking in prefrontal seizures

“…Established models of epilepsy networks based on signal analysis from intracerebral EEG data have shown that, during seizures, connections between neural groups in different anatomical structures are abnormally selected and facilitated [5,29]. In studying these relations between neural activities, most work to date on epilepsy networks has focused on the period of seizure onset [28]; relatively few works have investigated links to putative mechanisms of semiological production [18]. While firm conclusions cannot be drawn from the present work due to small number of data, our results suggest that correlating quantified ictal movement patterns with quantified cerebral data is feasible.…”

“…Complex rhythmic movements seen in some epileptic seizures involve automatic motor behaviors such as chewing or pedaling movements [26]. Such behaviors may be associated not only with epileptic seizures but also with sleep disorders [15] or other neurological conditions [10], and have been conceptualized as being associated with central pattern generators [26] likely involving subcortical circuitry [3,18]. When occurring in the context of a seizure, these more complex patterns are generally not concomitant with a focal seizure discharge confined to a single brain region but rather emerge when several connected structures within associative cortex are involved by early propagation of seizure discharge [2,5,8,18].…”

“…Not only anatomical constraints but also the temporal characteristics of the seizure discharge (e.g. rhythmicity, frequency, time-lag, coherence between structures) influence clinical expression [5,8,18].…”

On seizure semiology

“…Although seizure semiology is the tangible expression of epilepsy, and a key element in epilepsy diagnosis, classification, and localization, it can paradoxically appear an elusive and somewhat challenging entry point to understanding seizure organization, especially where correlation between semiology and EEG is not evident. In epileptic seizures, congruence can be observed in terms of the grouping and the evolution of clinical signs: Semiologic expression does not occur haphazardly but follows a sequence that is related to the cerebral progression of the seizure discharge, 14 with the organization of semiologic elements having been compared to “words in a meaningful sentence.” 15 We could also think of clinical seizure phenomenology as representing a specific behavioral architecture, with its own spatial and temporal dynamic 16 . On the other hand, although clearly linked to cerebral seizure activity, how exactly semiologic architecture maps onto cerebral dynamics remains elusive for many seizure patterns.…”

“…15 We could also think of clinical seizure phenomenology as representing a specific behavioral architecture, with its own spatial and temporal dynamic. 16 On the other hand, although clearly linked to cerebral seizure activity, how exactly semiologic architecture maps onto cerebral dynamics remains elusive for many seizure patterns.…”