Back to research

Research paper

Scalp EEG high frequency oscillations as a biomarker of treatment response in epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS)

Prospective pediatric CSWS cohort (n=22) treated with methylprednisolone, stratified by 2-week response and then by 3-month outcome. In the response-with-relapse subgroup (n=11), HFO detection was dramatically higher than ESES detection at every timepoint: 81.2% vs 27.3% at 2 weeks, 90.9% vs 36.4% at 3 months, 100% vs 54.5% at 6 months. Average IQ improved significantly only in the non-relapse subgroup. HFO persistence correlated negatively with IQ; ESES persistence did not. Authors propose HFOs as a non-invasive biomarker for predicting seizure and cognitive outcome.

Indexed context

Gong P, et al.

cswsesesdee-swashigh-frequency-oscillationshfosmethylprednisolonerelapse-biomarkereeg-biomarker

Markdown path

content/research/papers/2019-gong-csws-hfo-relapse-biomarker.md

Findings

Prospective pediatric CSWS cohort (n=22) treated with methylprednisolone, stratified by 2-week response and then by 3-month outcome. In the response-with-relapse subgroup (n=11), HFO detection was dramatically higher than ESES detection at every timepoint: 81.2% vs 27.3% at 2 weeks, 90.9% vs 36.4% at 3 months, 100% vs 54.5% at 6 months. Average IQ improved significantly only in the non-relapse subgroup. HFO persistence correlated negatively with IQ; ESES persistence did not. Authors propose HFOs as a non-invasive biomarker for predicting seizure and cognitive outcome.

Why it may matter for Levi

Reinforces that a clean-looking post-pulse EEG (Levi's UCSF 'occasional bursts') does not rule out ongoing subclinical epileptiform activity invisible to conventional SWI. If Levi's behavior is worsening due to true neurophysiological re-emergence, it could be HFO-level activity that the next conventional EEG would still miss. Provides a soft argument to ask the next EEG team about quantitative SWI and (where available) HFO analysis rather than relying solely on visual SWI estimation.

Paper text

Gong et al. (2019) — Scalp HFOs as a relapse biomarker in CSWS post-steroid

Source

Why this paper is in the corpus

This study is the cleanest pediatric CSWS demonstration that conventional SWI improvement does not exclude continued epileptiform activity — and that subclinical EEG markers (high-frequency oscillations, HFOs) can predict who will relapse months after a pulse looks like it worked.

Key findings

  • 22 children with CSWS, all received methylprednisolone.
  • Stratified by 2-week response (≥50% seizure reduction = "response group"), then "response group" further split into "relapse" vs. "non-relapse" by 3-month outcome.
  • In the response-with-relapse group (n=11), HFO detection was dramatically higher than ESES detection at every timepoint:
    • 2 weeks: 81.2% HFO vs. 27.3% ESES
    • 3 months: 90.9% HFO vs. 36.4% ESES
    • 6 months: 100% HFO vs. 54.5% ESES
  • Average IQ improved significantly only in the non-relapse subgroup.
  • HFO persistence correlated negatively with average IQ; ESES persistence did not.
  • Authors propose HFOs as a non-invasive biomarker for predicting seizure and cognitive outcome.

Limitations relevant to Levi

  • HFO analysis requires specialized signal processing not standardly performed on routine clinical EEG; Levi's UCSF and Stanford reports do not contain HFO metrics.
  • Small cohort (n=22).
  • "Response" was defined by seizure reduction, not SWI; Levi has no clinical seizures so this stratification doesn't map cleanly.

Levi-relevant takeaways

  • Reinforces that a clean-looking post-pulse EEG (Levi's UCSF "occasional bursts") does not rule out ongoing subclinical epileptiform activity that is silent on conventional SWI.
  • This means that if Levi's behavior is worsening due to true neurophysiological re-emergence, it could be driven by HFO-level activity that the next conventional EEG might still miss unless quantitative SWI and (ideally) HFO analysis are part of the protocol.
  • Provides a soft argument to ask the next EEG team about quantitative HFO availability rather than relying solely on visual SWI estimation.