High-density Flexible μECoG for Epilepsy Surgery - A Single-Arm ECT

1. Compare the effect of intraoperative high-density flexible μECoG guidance versus no intraoperative μECoG guidance on surgical prognosis in patients with drug-resistant focal epilepsy.
2. Explore intraoperative electrophysiological biomarkers recorded by high-density μECoG that are associated with surgical prognosis.

• Using High-density Flexible microElectrocorticography for intraoperative monitoring (Device): During resective epilepsy surgery, a sterile high-density flexible microelectrocorticography will be placed on the exposed cortical surface over the suspected epileptogenic zone and adjacent cortex. The array will be used for high-spatial-resolution intraoperative μECoG recording and real-time analysis of epileptiform activity, including interictal spikes, high-frequency oscillations, spatial discharge gradients, and propagation patterns. The intraoperative ECoG findings will be provided to the surgical team to assist in defining the epileptogenic zone and tailoring the extent of resection. The high-density μECoG is used for intraoperative recording only and will be removed before wound closure.

Primary outcomes

• Seizure Freedom Rate at 6 Months After Surgery [From surgery to 6 months postoperatively]: The proportion of participants who remain free from any type of epileptic seizure during the 6-month postoperative follow-up period.

Secondary outcomes

• Seizure Freedom Rate at 1 Year After Surgery [From surgery to 1 year postoperatively]: The proportion of participants who remain free from any type of epileptic seizure during the 1-year postoperative follow-up period.
• Postoperative Seizure Outcome According to ILAE Classification [6 months and 1 year postoperatively]: Postoperative seizure outcome will be evaluated using the International League Against Epilepsy classification at 6 months and 1 year after surgery. ILAE class 1 indicates complete seizure freedom without aura, and higher classes indicate worse seizure outcomes.
• Monthly Seizure Frequency [Baseline, 6 months postoperatively, and 1 year postoperatively]: Monthly seizure frequency will be assessed before surgery and at 6 months and 1 year after surgery. The measure is defined as the average number of epileptic seizures per month.
• Seizure Severity Assessed by the National Hospital Seizure Severity Scale [Baseline, 6 months postoperatively, and 1 year postoperatively]: Seizure severity will be assessed using the National Hospital Seizure Severity Scale (NHS3) before surgery and at 6 months and 1 year after surgery. The NHS3 is a seizure severity scale with scores ranging from 1 to 27, with higher scores indicating more severe seizures and therefore a worse outcome.
• Developmental Function Assessed by the Griffiths Mental Development Scales [Baseline, 6 months postoperatively, and 1 year postoperatively]: For participants aged 3 to 6 years, developmental function will be evaluated using the Griffiths Mental Development Scales before surgery and at 6 months and 1 year after surgery. The primary reported score will be the General Developmental Quotient or General Quotient. The quotient score ranges from 50 to 150, with higher scores indicating better developmental function and therefore a better outcome.
• Cognitive Function Assessed by the Wechsler Intelligence Scale for Children [Baseline, 6 months postoperatively, and 1 year postoperatively]: For participants aged 6 to 16 years, cognitive function will be evaluated using the Wechsler Intelligence Scale for Children before surgery and at 6 months and 1 year after surgery. The primary reported score will be the Full Scale Intelligence Quotient. The Full Scale Intelligence Quotient standard score ranges from 40 to 160, with higher scores indicating better cognitive function and therefore a better outcome.
• Cognitive Function Assessed by the Mini-Mental State Examination [Baseline, 6 months postoperatively, and 1 year postoperatively]: For participants older than 16 years, cognitive function will be evaluated using the Mini-Mental State Examination (MMSE) before surgery and at 6 months and 1 year after surgery. The MMSE total score ranges from 0 to 30, with higher scores indicating better cognitive function and therefore a better outcome.
• Quality of Life Assessed by the Quality of Life in Epilepsy Inventory-31 or the Pediatric Quality of Life Inventory Version 4.0 [Baseline, 6 months postoperatively, and 1 year postoperatively]: Quality of life will be evaluated before surgery and at 6 months and 1 year after surgery. Adult participants will be assessed using the Quality of Life in Epilepsy Inventory-31 (QOLIE-31), and pediatric participants will be assessed using the Pediatric Quality of Life Inventory Version 4.0 (PedsQL 4.0). Both scales are transformed to scores ranging from 0 to 100, with higher scores indicating better quality of life and therefore a better outcome.
• Postoperative Complications [Perioperative period, 6 months postoperatively, and 1 year postoperatively]: The incidence of postoperative complications, including infection, fever, neurological deficits, and other surgery-related complications, will be recorded during the perioperative period and postoperative follow-up.
• Surgery-Related Adverse Events [Perioperative period]: The incidence of surgery-related adverse events will be recorded during the perioperative period. Adverse events include events directly related to the surgical procedure.
• Serious Adverse Events [Perioperative period]: The incidence of serious adverse events, including postoperative death or severe deterioration of health status during the perioperative period, will be recorded.

Sex: All, ages: 3 Years to 60 Years

Inclusion Criteria:

1. Age 3 to 60 years.
2. Diagnosis of drug-resistant epilepsy, defined as persistent seizures despite treatment with two or more appropriately selected, adequately dosed and adequately tried antiseizure medications.
3. Diagnosis of focal epilepsy after standard presurgical evaluation and considered suitable for resective epilepsy surgery.
4. Preoperative cognitive or developmental status sufficient to participate in study assessments, as judged by the investigator and assessed using age-appropriate validated instruments. For participants aged 3 to 6 years, developmental status must be within the normal range according to the Griffiths Mental Development Scales. For participants aged 6 to 16 years, cognitive function must be within the normal range according to the Wechsler Intelligence Scale for Children. For participants older than 16 years, a Mini-Mental State Examination score of 24 or higher will be required.
5. Written informed consent provided by the participant or, when applicable, by a legal guardian.

Exclusion Criteria:

1. Suspected mesial temporal lobe epilepsy after multidisciplinary presurgical evaluation.
2. History of any previous neurosurgical craniotomy before epilepsy surgery.
3. Severe psychiatric, cognitive, or psychological disorder that prevents participation in the study or completion of follow-up.
4. Contraindication to surgery.

• Xingjian Liu, Chao Zhang, Baotian Zhao, et al., Preliminary application study of flexible high-density cortical electrodes in assisting localization of epileptogenic zones during epileptogenic zonectomy, Chinese Journal of Neurosurgery, 2025, 41(12):1237-1244. DOI:10.3760/cma.j.cn112050-20250919-00362
• Guo J, Wang Z, van 't Klooster MA, Van Der Salm SM, Leijten FS, Braun KP, Zijlmans M. Seizure Outcome After Intraoperative Electrocorticography-Tailored Epilepsy Surgery: A Systematic Review and Meta-Analysis. Neurology. 2024 Jun 11;102(11):e209430. doi: 10.1212/WNL.0000000000209430. Epub 2024 May 20. PMID 38768406