Abstracts

Rationale: Juvenile Myoclonic Epilepsy (JME) is clinically defined by myoclonic jerks and generalised tonic clonic seizures. JME is classified as generalized epilepsy syndrome, but there is increasing evidence for predominantly frontal pathology. We applied functional magnetic resonance imaging (fMRI) to investigate the cortical activation pattern during a working memory task. Methods: We examined 18 patients with JME and 22 healthy controls. Subjects performed a spatial working memory fMRI task (‘Dot Back’), with three different memory loads (0-back, 1-back, 2-back) and a rest condition (cross-hair fixation). Response to the task and success rate were monitored via a joystick. fMRI analysis was carried out using SPM 5 software. We used the contrast of “2-back minus 0-back” for second-level comparison between groups. This contrast controls for motor activity and visual input. Results: Patients and controls showed strong bilateral task-related activation in the dorsolateral prefrontal cortex, superior frontal gyrus and the superior parietal lobe (T-scores > 8). JME patients showed higher activation of the left motor cortex and reduced bilateral temporal activation compared to controls. Within group analysis revealed increased left motor cortex activation in JME correlated with task performance scores, whilst controls showed the highest correlation in the right parietal lobe as expected for a demanding spatial processing task. Conclusions: These findings provide evidence for an increased functional coupling between “frontal lobe” cognitive networks and motor cortex in JME patients. Evidence for hyperexcitability of motor cortex is an interesting finding, given the predominant clinical seizure type with myoclonic jerks which have been reported to be triggered by cognitive activity.