Functional MRI interactions between dysplastic nodules and overlying cortex in periventricular nodular heterotopia

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Epileptology

Background:

• Periventricular nodular heterotopia (PVNH) is a neuronal migration disorder.
• PVNH is frequently associated with epilepsy, but the precise epileptogenic zone remains unclear.
• Identifying the epileptogenic focus in PVNH is crucial for effective treatment.

Observation:

• Electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) was performed on a patient with bilateral PVNH.
• The study captured 45 left temporal epileptiform discharges.
• fMRI data revealed activity in both periventricular nodules and the overlying cortex in the left temporoparietal region.

Findings:

• EEG-fMRI demonstrated concurrent activity in epileptogenic nodules and adjacent cortex.
• The blood-oxygen-level-dependent (BOLD) response in these regions peaked earlier than predicted by standard hemodynamic models.
• Functional connectivity analysis revealed strong interactions between nodules and cortex in the epileptogenic zone, even after accounting for spiking-related fMRI fluctuations.
• Non-epileptogenic nodules showed no significant connectivity with their overlying cortex.

Implications:

• EEG-fMRI and functional connectivity are valuable tools for localizing epileptogenic regions in PVNH.
• These techniques can differentiate between potentially epileptogenic and non-epileptogenic lesions in patients with multiple heterotopic nodules.
• Understanding nodule-cortex interactions provides insights into the pathophysiology of epilepsy in PVNH.