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Updated: Oct 11, 2026
Stereo-Electro-Encephalo-Graphy (SEEG) With Robotic Assistance in the Presurgical Evaluation of Medical Refractory Epilepsy: A Technical Note
Published on: June 13, 2016
Complementing Engel Classification: Postoperative Scalp EEG as an Objective Indicator in SEEG-Guided Radiofrequency
Yi-Qing Yang1, Rui Zhang1,2, Haiyan Ma2
1Department of Functional Neurosurgery, Nanjing Brain Hospital Affiliated to Nanjing Medical University, Nanjing, China.
Background:
Stereoelectroencephalography-guided radiofrequency thermocoagulation (SEEG-RFTC) is a minimally invasive therapy for drug-resistant focal epilepsy. However, the relationship between specific seizure-onset patterns (SOPs), particularly low-voltage fast activity (LVFA), and postoperative scalp EEG normalization remains inadequately characterized. This study investigates whether LVFA predicts RFTC efficacy and whether postoperative EEG serves as an objective complement to clinical outcome measures.
Objective:
To evaluate LVFA-dominant SOPs as predictors of seizure freedom and scalp EEG normalization after SEEG-RFTC, and to assess their interaction with MRI findings.
Methods:
In a retrospective cohort of 25 patients, seizure-onset patterns (SOPs) were classified as LVFA-present (n = 13) or LVFA-absent (n = 12). Outcomes included Engel classification and 6-month postoperative scalp EEG. Seizure freedom and EEG normalization rates were compared, with MRI-stratified analysis.
Results:
The seizure-free rate was 92.3% (12/13) in the LVFA-present group versus 33.3% (4/12) in the LVFA-absent group (p = 0.004). EEG normalization was more frequent in LVFA-present patients (7/8, 87.5%) than in LVFA-absent patients (4/12, 33.3%; p = 0.028); all but one patient with EEG normalization was seizure-free, the sole exception being an LVFA-absent patient who remained Engel III. In MRI-negative patients, LVFA-present had 100% (6/6) seizure freedom versus 20.0% (1/5) without LVFA (p = 0.015). Scalp EEG normalization may serve as a relatively objective marker of complete disintegration of the epileptic network, whereas some patients with persistent EEG abnormalities may still achieve seizure freedom with the aid of antiseizure medications.
Conclusion:
In this cohort, LVFA-present SOPs are strongly associated with favorable RFTC outcomes and may represent a prerequisite for postoperative scalp EEG normalization. Postoperative EEG is a sensitive objective endpoint that complements Engel classification. Systematic PET evaluation in larger cohorts may further refine candidate selection in MRI-negative patients.
