Neuropediatrics 2006; 37 - THP83
DOI: 10.1055/s-2006-945906

SPATIO-TEMPORAL CHANGES OF ICTAL HIGH FREQUENCY OSCILLATIONS IN PEDIATRIC NEOCORTICAL EPILEPSY

A Ochi 1, H Otsubo 1, I Elliott 1, E Donner 1, J Rutka 1, OC Snead III 1
  • 1Division of Neurology, The Hospital for Sick Children, Toronto, ON, Canada

Objectives: High-frequency oscillations (HFOs) have been recognized in epileptic regions. We retrospectively analyzed ictal subdural EEG by using multiple band frequency analysis (MBFA) in children with intractable neocortical epilepsy. Our objectives were 1) to define the correlation between the area with HFOs and resection area, 2) to evaluate the distribution of HFOs and the post-surgical seizure outcome.

Methods: We retrospectively studied 9 children (4 girls and 5 boys, mean age, 12.2 years; range, 4 to 17 years) who presented with intractable extra-hippocampal localization-related epilepsy and who underwent extraoperative video subdural EEG and focal cortical resections. We performed MBFA to identify the frequency and distribution of HFOs. We compared the frequency and distribution of HFOs before and after the clinical seizure onset and post-surgical seizure outcome. Results: In 4 patients seizure free post-operatively, MBFA showed more electrodes with HFOs inside the resection area than outside in >60% of seizures, both before and after clinical seizure onset. In 5 patients with residual seizures, more electrodes with HFOs were detected outside the resection area than inside in >65% of seizures. Before clinical onset, in all 9 patients, the electrodes with faster HFOs were resected in >2/3 of seizures. After clinical onset, in 4 patients seizure free post-operatively, electrodes with faster HFOs were predominantly resected in 87% of seizures. In 3 of 5 patients with residual seizures, >75% of seizures had electrodes with faster HFOs outside the resection area. Two patients with residual seizures showed faster HFOs inside than outside the resection area after the clinical onset, but there were more electrodes with HFOs outside than inside before and after the clinical onset.

Conclusion: Complete resection of the electrodes with HFOs, including the electrodes with fastest HFOs, may achieve the best post-surgical outcome.