Interictal discharges have neuropsychological effects in rolandic epilepsy

By Lucy Piper, Senior medwireNews Reporter

Centrotemporal spikes experienced between seizures by children with rolandic epilepsy may disrupt functional brain networks and contribute to language, behaviour and cognitive problems, research suggests.

The research team, led by Dong Zhou (Sichuan University, Chengdu, China), therefore recommend more aggressive suppression of rolandic epileptiform discharges in order to reduce the risk of such impairments.

Zhou and colleagues used electroencephalogram functional magnetic resonance imaging to study dynamic functional connectivity before, during and after periods of centrotemporal spikes in 22 drug-naïve children with rolandic epilepsy.

The participants, aged between 8 and 14 years, experienced 51 to 177 spikes during a total scan time of 406 seconds.

During the progression of centrotemporal spikes, positive correlations were seen between brain activity in the bilateral rolandic areas and in language-processing regions of the brain, specifically the left inferior frontal gyrus (IFG), the left inferior parietal lobe and the left supramarginal gyrus (SMG).

The transient effects of centrotemporal spikes on these areas may therefore present as expressive speech difficulties, including reading and fluency difficulties, as well as subsequent memory problems and learning difficulties, the team suggests.

Indeed, they found that scores for verbal IQ on the Wechsler Intelligence Scale for Children correlated significantly with the dynamic functional connectivity of the left SMG and right rolandic operculum in the phases before and after centrotemporal spikes.

And performance IQ negatively correlated with dynamic functional connectivity between the left rolandic operculum and the left IFG, the triangular part, in the phase before centrotemporal spikes.

Positive correlations with centrotemporal spikes were also seen for functional connectivity of the right IFG and the left caudate, which Zhou et al say is another important finding indicating transient effects on inhibition and executive and attentional functions.

“This negative impact was embodied in the aggressive behaviour, social problems, attention problems, and delinquency reported by the patients’ parents and teachers”, they note in Neurology.

Not all functional connectivity correlations were positive, however; negative correlations were evident between the rolandic areas and the bilateral superior frontal gyrus, left middle frontal gyrus, left middle temporal gyrus and right precuneus.

These areas form part of the default mode network, connection disturbances in which contribute to several neuropsychiatric disorders, affect task performance and induce fluctuations in consciousness, the team warns.

“The role of interictal epileptic discharges is gaining greater importance as a putative mechanism by which epilepsy interferes with the brain functional connectivity baseline, thereby leading to cognitive impairment”, they comment.

“Our observations support the hypothesis that the inhibitory effects of epileptiform activity on the default mode of brain function affect cognition in epilepsy patients.”

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