Authors :
Presenting Author: Minette Krisel Manalo, MD – Alberta Children's Hospital, University of Calgary
Daniel Lachner-Piza, Post Doctoral Fellow – University of Calgary; Margarita Maltseva, Post Doctoral Fellow – University of Calgary; Julia Jacobs Le-Van, Pediatric Neurologist-Epileptologist – Alberta Children's Hospital, University of Calgary; Juan Pablo Appendino, Pediatric Neurologist-Epileptologist – Alberta Children's Hospital, University of Calgary; Alice Ho, Pediatric Neurologist-Epileptologist – Alberta Children's Hospital, University of Calgary; Morris Scantlebury, Pediatric Neurologist-Epileptologist – Alberta Children's Hospital, University of Calgary
Rationale:
High Frequency Oscillations (HFO) are shown to be biomarkers to track epilepsy severity. HFOs have been mainly studied in the intracranial electro-encephalogram (EEG). However, studies have shown how scalp HFOs correspond to disease severity and surgical therapy response. This extension to scalp EEG allows to study pediatric patients not only with focal but also genetic generalized epilepsies. Here we analyzed HFO, HFO plus spikes, and spikes in patients before and after anti-seizure treatments. Our goal is to explore whether treatment success is reflected by a decrease in HFO and spikeHFO activity.
Methods:
Medical records and EEG database were systematically searched for patients that met the following inclusion criteria: diagnosis of genetic generalized epilepsy, at least two scalp EEG (pre-intervention, post-intervention) at a sampling rate of >1000Hz, at least 20 minutes of low-artifact EEG segments. For all selected patients, outcome was categorized as: (i) Improved EEG; (ii) Clinical Improvement; (iii) Seizure Freedom. A certified neurophysiologist marked the HFO and spikes using an in-house visualization program. Occurrence rates were calculated for visually marked HFO and spike for each EEG channel. Agreement between automatic detectors and visual marks were measured using the Spearman’s rank correlation coefficient. Statistical analysis was conducted with the data generated by the MOSSDET detector (HFO) and Delphos detector. Each outcome group were then tested to see if HFO and spikeHFO activity showed a significant decrease after the anti-epilepsy intervention (AEI).
Results:
Twelve patients were included. Six had an improved EEG, eight had clinical improvement, and six were seizure free. There were significant reductions in HFO, spikeHFO, and spike rates for patients with EEG (HFO p< 0.01, Spike&HFO p< 1x10
-16, spike p< 0.05) and clinical (HFO p< 0.01, Spike&HFO p< 1x10
-10, spike p< 0.05) improvements. For patients with seizure freedom, only spikeHFO rates were significantly reduced
(p< 1x10
-4) after AEI. (Figure 1)
Conclusions:
There was a significant decrease in the HFO, spikeHFO, and spike rates for all patients who had EEG and clinical improvement after AEI. SpikeHFO activity additionally showed a significant decrease when the patients became seizure free. Thus, HFO, spikeHFO, and spike activity reflect response to treatment and improvement thru therapy. This can be used to assess treatment success in generalized epilepsies, further studies are needed to assess whether HFO also could be used to predict treatment success.
Funding: Grant: Canadian Institutes of Health Research