Clinical Scorecard: Surgical Approaches for Seizure Control in Low-Grade Gliomas: The Role of Supratotal Resection (ETT-SpTR) Utilizing Electrocorticography and Navigated Transcranial Magnetic Stimulation

At a Glance

Key Highlights

• Seizures frequently persist after gross total resection (GTR) due to epileptic foci outside the tumor mass.
• Supratotal resection (SpTR) including epileptic foci identified by intraoperative electrocorticography (iECoG) improves seizure control.
• Navigated transcranial magnetic stimulation (nTMS) validated by direct cortical stimulation helps preserve eloquent cortex during extended resections.

Guideline-Based Recommendations

Diagnosis

• Use standard EEG to identify epileptic (interictal or ictal) activity preoperatively.
• Perform preoperative MRI with diffusion tensor imaging (DTI) for tumor and white matter tract visualization.
• Apply navigated transcranial magnetic stimulation (nTMS) to map motor, language, and calculation cortical functions.

Management

• Initiate antiseizure therapy with Levetiracetam at 500 mg twice daily preoperatively and continue 1000 mg/day postoperatively.
• Employ intraoperative electrocorticography (iECoG) to localize epileptic foci during surgery.
• Perform supratotal resection (SpTR) tailored by iECoG and nTMS (ETT-SpTR) to include epileptic foci while preserving functional cortex.
• Avoid Propofol anesthesia intraoperatively to prevent suppression of iECoG signals; use Dexmedetomidine and Remifentanil instead.

Monitoring & Follow-up

• Intraoperative EEG monitoring using Cz'-Fz, C3'-Fz, C4'-Fz, and C3'-C4' montages.
• Repeat iECoG recordings before, during, and after resection to assess interictal epileptiform activity.
• Use neuronavigation integrating MRI, DTI, and nTMS data to monitor distance from functional areas during resection.

Risks

• Risk of neurological deficits if eloquent cortex is resected; mitigated by nTMS and direct cortical stimulation validation.
• Incomplete seizure control if epileptic foci are not fully resected due to tumor infiltration and proximity to functional areas.

Patient & Prescribing Data

Patients with LGG and preoperative epileptic seizures

Levetiracetam is used as first-line antiseizure medication starting preoperatively and maintained postoperatively to manage seizures.

Clinical Best Practices

• Combine preoperative nTMS mapping with intraoperative iECoG to identify epileptic foci and functional cortex accurately.
• Tailor supratotal resection (ETT-SpTR) to include epileptic foci while preserving eloquent brain areas to optimize seizure control and functional outcomes.
• Avoid anesthetic agents that suppress cortical activity during iECoG to ensure accurate intraoperative monitoring.
• Use neuronavigation integrating multimodal imaging and functional data to guide safe resection margins.

References

• Epileptic seizures in LGG and seizure persistence after GTR
• Role of supratotal resection in seizure control
• Navigated transcranial magnetic stimulation for cortical mapping
• Intraoperative electrocorticography techniques
• Levetiracetam dosing and management in LGG patients