3D visualization of subdural electrode shift as measured at craniotomy reopening

Area of Science:

• Neurosurgery
• Medical Imaging
• Epilepsy Research

Background:

• Subdural electrodes are crucial for identifying seizure onset zones in medically refractory epilepsy.
• Accurate electrode placement is vital for successful surgical resection.
• Current surgical planning often assumes electrodes remain stationary, lacking precise post-placement data.

Purpose of the Study:

• To quantify the shift in subdural electrode position relative to the cortical surface between placement and subsequent surgical reopening.
• To assess the impact of electrode shift on surgical planning for epilepsy.
• To evaluate the necessity of 3D imaging for precise electrode localization.

Main Methods:

• Collected CT and structural MRI data from 10 epilepsy surgery patients post-electrode implantation.
• Created patient-specific 3D cortical surface models from MRI.
• Co-registered CT data to MRI, isolating electrodes for positional analysis.
• Measured electrode displacement using intraoperative navigation during surgical reopening.

Main Results:

• Statistically significant electrode shift occurred in 50% of patients (5/10).
• Mean overall electrode shift magnitude was 7.2mm.
• Significant decompression-based shift (mean 4.7mm) and shear displacement (mean 7.1mm) were observed in subsets of patients.

Conclusions:

• Electrode shift relative to the cortical surface is a significant factor in epilepsy surgery.
• The findings underscore the utility of 3D imaging (CT/MRI) for accurate electrode localization.
• Integrating 3D models with intraoperative measurements can improve surgical boundary definition and outcomes.