Mapping intraoperative interictal epileptiform discharges using high-resolution, thin-film cortical arrays

Area of Science:

• Neuroscience
• Biomedical Engineering
• Epilepsy Research

Background:

• Interictal epileptiform discharges (IEDs) are key indicators of epilepsy, traditionally detected using scalp or intracranial electroencephalogram (EEG) macrocontacts.
• Standard EEG methods offer limited spatiotemporal resolution, potentially missing crucial microscale activity patterns.

Purpose of the Study:

• To investigate the utility of high-resolution microelectrocorticographic (μECoG) arrays for capturing IEDs with enhanced spatiotemporal precision.
• To determine if microscale IED patterns exist that are undetectable by conventional intracranial EEG macroarrays.

Main Methods:

• Utilized flexible, high-resolution μECoG arrays (0.76-1.72 mm spacing) for intraoperative recording in seven epilepsy patients.
• Employed expert review and automated detection to identify IEDs, quantifying their spatial extent and propagation.
• Compared μECoG data with simulated macroarray recordings to assess detection rate differences.

Main Results:

• Successfully mapped intraoperative microscale IED patterns using μECoG arrays.
• Observed highly localized IED activity in the majority of patients (5/7), with 40% within a 4-mm cortical radius.
• Found that an average of 39% of μECoG-detected IEDs were missed by simulated macrocontacts, highlighting limitations of standard methods.

Conclusions:

• μECoG arrays effectively map the microscale spatiotemporal activity of IEDs, revealing patterns often missed by macroscale devices.
• These high-resolution, large-coverage arrays offer significant potential for improved presurgical and intraoperative mapping of epileptic cortex.
• Findings support the clinical integration of μECoG technology for more precise epilepsy characterization.