High-Frequency Oscillations on Interictal Epileptiform Discharges in Routinely Acquired Scalp EEG: Can It Be Used as
Hanan El Shakankiry1, Susan T Arnold1
1UT Southwestern Medical School, Children's Health, Dallas, TX, United States.
Insights
High-frequency oscillations (HFOs) accompanying epileptiform discharges (EDs) in pediatric EEG predict a higher risk of seizure recurrence. This finding aids in guiding anti-seizure medication (ASM) decisions for children with epilepsy.
Area of Science:
- Pediatric Neurology
- Epileptology
- Neurophysiology
Background:
- Optimizing epilepsy management in children remains challenging due to unclear consensus on treating epileptiform discharges (EDs) after a first unprovoked seizure.
- Identifying reliable markers on scalp electroencephalogram (EEG) to guide treatment decisions for pathological EEG discharges is crucial.
Purpose of the Study:
- To determine if the presence of ripples/high-frequency oscillations (HFOs) alongside interictal EDs (IEDs) in routine scalp EEG predicts seizure recurrence in children.
- To evaluate HFOs as a potential prognostic marker in pediatric epilepsy.
Main Methods:
- Retrospective analysis of 100 children with new-onset seizures and focal EDs on EEG, who were not on anti-seizure medication (ASM).
- EEGs were acquired at 500 Hz and analyzed blinded to patient data, with HFOs visually identified.
- Inter-rater reliability for HFO identification was assessed.
Main Results:
- High-frequency oscillations (HFOs) were identified in 19% of patients, with higher prevalence in younger children and association with spikes and higher amplitude EDs.
- Patients with HFOs showed a significantly higher likelihood of seizure recurrence within one year and continued seizures after two years.
- No significant difference was observed in the decision to continue ASM after two years between groups.
Conclusions:
- Analysis of HFOs in routine EEG can enhance diagnostic yield and inform decisions regarding the initiation or discontinuation of ASM.
- Identifying HFOs may help pinpoint pathological discharges with adverse effects on brain development, potentially establishing new therapeutic targets in epilepsy management.
Introduction:
Despite all the efforts for optimizing epilepsy management in children over the past decades, there is no clear consensus regarding whether to treat or not to treat epileptiform discharges (EDs) after a first unprovoked seizure or the optimal duration of therapy with anti-seizure medication (ASM). It is therefore highly needed to find markers on scalp electroencephalogram (EEG) that can help identify pathological EEG discharges that require treatment.
Aim Of The Study:
This retrospective study aimed to identify whether the coexistence of ripples/high-frequency oscillations (HFOs) with interictal EDs (IEDs) in routinely acquired scalp EEG is associated with a higher risk of seizure recurrence and could be used as a prognostic marker.
Methods:
100 children presenting with new onset seizure to Children's Medical Center- Dallas during 2015-2016, who were not on ASM and had focal EDs on an awake and sleep EEG recorded with sample frequency of 500 HZ, were randomly identified by database review. EEGs were analyzed blinded to the data of the patients. HFOs were visually identified using review parameters including expanded time base and adjusted filter settings.
Results:
The average age of patients was 6.3 years (±4.35 SD). HFOs were visually identified in 19% of the studied patients with an inter-rater reliability of 99% for HFO negative discharges and 78% agreement for identification of HFOs. HFOs were identified more often in the younger age group; however, they were identified in 11% of patients >5 years old. They were more frequently associated with spikes than with sharp waves and more often with higher amplitude EDs. Patients with HFOs were more likely to have a recurrence of seizures in the year after the first seizure (P < 0.05) and to continue to have seizures after 2 years (P < 0.0001). There was no statistically significant difference between the two groups with regards to continuing ASM after 2 years.
Conclusion:
Including analysis for HFOs in routine EEG interpretation may increase the yield of the study and help guide the decision to either start or discontinue ASM. In the future, this may also help to identify pathological discharges with deleterious effects on the growing brain and set a new target for the management of epilepsy.
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