Electroclinical features and dynamic network connectivity of orbitofrontal epilepsy

Area of Science:

• Neuroscience
• Epileptology
• Network Neuroscience

Background:

• Orbitofrontal epilepsy (OFE) is an underrecognized and rare epilepsy syndrome.
• Characterizing its electroclinical features and network dynamics is crucial for diagnosis and treatment.

Purpose of the Study:

• To define the electroclinical characteristics of OFE.
• To investigate dynamic network connectivity in OFE subtypes.
• To evaluate the diagnostic and therapeutic utility of stereoelectroencephalography (SEEG).

Main Methods:

• Retrospective analysis of 17 patients with OFE undergoing SEEG implantation and surgery.
• Categorization into lateral (LOFE), medial (MOFE), and posterior (POFE) OFE subtypes based on ictal SEEG.
• Analysis of clinical semiology, EEG, neuroimaging, and SEEG data, including directed functional connectivity.

Main Results:

• OFE semiology was heterogeneous, with impaired consciousness, motor phenomena, and automatisms being common.
• SEEG revealed seizure activity preceding clinical onset (mean delay 28.9s).
• Distinct connectivity patterns were observed between LOFE and MOFE subtypes during ictal periods; functional connectivity increased throughout seizures.
• SEEG improved localization accuracy compared to scalp EEG/imaging.
• Favorable surgical outcomes (Engel class I: 84.6%) were achieved, with focal cortical dysplasia being the most common pathology.

Conclusions:

• OFE subtypes display unique semiological features and network connectivity profiles, linked to frontal-limbic network engagement.
• Targeted SEEG facilitates accurate localization and generally positive surgical outcomes in OFE.