Abstracts

Rationale: Little is known on occurrence and causes of changing seizure semiology in the individual patient. We aimed to assess the relation between changing semiology and age in patients with partial epilepsy, and to elucidate the underlying functional brain networks. Methods: Patients with refractory symptomatic or cryptogenic partial epilepsy were selected from the Dutch Collaborative Epilepsy Surgery Program, and included in this study if at least two consecutive ictal video EEG recording had been performed. We analyzed changes in semiology in relation to ictal onset zones in the individual patient. Cerebral MRI scans were available for each patient. Graph theoretical analysis will be applied to further elucidate the observed changes in ictal onset zones and semiology. Results: Seizure semiology with age had changed in 14 of the 15 patients observed during consecutive video EEG recordings. Changes included appearance or disappearance of lateralization of motor function, automatisms, lowered consciousness, and postictal signs. In 9 of the 15 children, changing semiology had been related to changing ictal onset zones. Progression in structural MRI abnormalities were identified in two children, potentially accountable for the change in both semiology and ictal onset zones. Graph theoretical analysis will be applied in the children with stationary lesions. In 5 out of 15 children, ictal onset zones had not changed. In one child, video EEG recordings were insufficient for analysis. Conclusions: Semiology often changes with age in relation to changes in ictal onset zones. Structural alterations are accountable for this change only in the minority of patients. Graph theoretical analysis is applied as a novel model to relate changes in semiology to age. We suggest that new insights into the neural substrates for changing semiology/ epileptogenic zones we be gained.