Interhemispheric subdural electrodes: technique, utility, and safety

Area of Science:

• Neurosurgery
• Epileptology
• Medical Devices

Background:

• Intractable epilepsy often requires invasive monitoring to pinpoint seizure origins.
• Interhemispheric electrode placement presents unique surgical challenges and potential risks compared to dorsolateral approaches.

Purpose of the Study:

• To evaluate the safety and clinical utility of interhemispheric subdural electrodes (IHSE) for epilepsy monitoring.
• To assess the complication rates associated with IHSE implantation.

Main Methods:

• Retrospective chart review of 24 patients who underwent IHSE implantation between 2003 and 2010.
• Surgical technique emphasized generous midline exposure, vein preservation, and sharp microdissection for safe electrode placement.
• Direct visualization was used during implantation.

Main Results:

• IHSE monitoring captured adequate seizure samples in all patients with a low complication rate, comparable to dorsolateral grids.
• Only one patient experienced symptomatic mass effect; other complications like deficits, infection, or infarction were not observed.
• IHSE monitoring guided successful paramedian cortical resection in 67% of patients.

Conclusions:

• Interhemispheric subdural electrodes provide a safe and effective means to monitor and define the epileptogenic zone in patients with suspected midline epilepsy foci.
• This technique aids in mapping local cortical function and guiding surgical intervention for intractable epilepsy.