Long-term satisfaction after extraoperative invasive EEG recording

Masaki Sonoda, Alanna Carlson, Robert Rothermel, Naoto Kuroda, Hirotaka Iwaki, Aimee F. Luat, Sandeep Sood, Eishi Asano

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


This retrospective cohort study investigated 53 patients with drug-resistant focal epilepsy and identified factors predictive of long-term satisfaction of patients and families following extraoperative intracranial EEG (iEEG) recording. The mixed model analysis assessed the utility of intracranial EEG (iEEG) predictor variables, including the seizure-onset zone (SOZ), modulation index (MI), and naming-related high-gamma activity. Modulation index, quantifying the coupling between high-frequency activity at >80 Hz and local slow wave at 3–4 Hz, effectively functions as a surrogate marker of the burden of interictal spike-and-slow-wave discharges. The mixed model specifically incorporated 'subtraction-MI', defined as the subtraction of mean z-score normalized MI across all preserved sites from that across all resected sites. Auditory naming-related high-gamma activity at 70–110 Hz is a biomarker to characterize the underlying language and speech function. The model incorporated 'maximum resected high-gamma', defined as the high-gamma percent change largest among sites included in the resected language-dominant hemispheric region. The model also incorporated the clinical and imaging profiles of given patients. The analysis revealed that complete removal of SOZ (p = 0.003) and younger patient age (p = 0.040) were independently associated with greater satisfaction. Neither ‘subtraction-MI’ nor 'maximum naming-related high-gamma' showed a significant and independent association with long-term satisfaction in our patient cohort. The observed impact of complete resection of SOZ and early surgery can be considered when counseling candidates for epilepsy surgery.

Original languageEnglish
Article number108363
JournalEpilepsy and Behavior
StatePublished - Nov 2021


  • High-frequency oscillations (HFOs)
  • Intracerebral EEG
  • Pediatric epilepsy surgery
  • Phase-amplitude coupling
  • Ripples


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