Intracranial electroencephalogram to evaluate refractory temporal and frontal lobe epilepsy

Area of Science:

• Neurology
• Neurosurgery
• Epileptology

Background:

• Refractory epilepsy presents diagnostic challenges for presurgical evaluation.
• Multidisciplinary teams are crucial for complex epilepsy management.
• Accurate localization of epileptogenic zones is key for successful surgical intervention.

Purpose of the Study:

• To test a hypothesis regarding the placement of intracranial electroencephalography (iEEG) arrays in refractory epilepsy patients.
• To evaluate the utility of iEEG in delineating seizure-onset zones and eloquent areas.
• To assess surgical outcomes and pathology results following iEEG-guided interventions.

Main Methods:

• A descriptive case series of 105 refractory epilepsy patients undergoing non-invasive presurgical evaluations.
• Hypothesis generation for discordant cases using advanced neuroimaging (PET, SPECT, fMRI, Wada tests).
• Indications for iEEG included focal or multi-focal MRI findings and scalp EEG results, with 10 patients undergoing iEEG.

Main Results:

• iEEG successfully defined epileptogenic zones in all 10 patients.
• Functional mapping delineated eloquent areas in 6 patients.
• Four of seven surgically treated patients achieved favorable Engel class I/II outcomes, with variable success across patient groups.

Conclusions:

• Intracranial electroencephalography is a valuable tool in the presurgical evaluation of refractory epilepsy.
• This management modality offers potential benefits for patients with difficult-to-treat epilepsy.
• The utilization of iEEG for refractory epilepsy presurgical evaluation is currently limited.