Internodular functional connectivity in heterotopia-related epilepsy

Area of Science:

• Neuroscience
• Epileptology
• Medical Imaging

Background:

• Gray matter heterotopia with multiple nodules often presents with difficult-to-treat epilepsy.
• A complex network involving nodules and cortices is implicated in epileptogenicity.

Purpose of the Study:

• To determine if functional magnetic resonance imaging (fMRI) can detect internodular functional connectivity (FC).
• To ascertain if detected FC reflects synchronized neuronal activity and contributes to epileptogenicity.

Main Methods:

• Studied 16 epilepsy patients with multiple heterotopic nodules, with eight undergoing intracerebral EEG.
• Examined internodular FC using fMRI and correlated it with intracerebral interictal activity synchrony.
• Compared seizure activity spread speed and FC between nodule pairs based on seizure onset involvement.

Main Results:

• 83% of 70 studied nodules showed significant connection to at least one other nodule.
• fMRI-connected pairs exhibited more synchronized interictal activity (P < 0.05).
• Ictal activity spread faster between connected pairs (P < 0.0001), with stronger FC in nodules involved at seizure onset (P < 0.01).

Conclusions:

• fMRI reliably detects FC between heterotopic nodules noninvasively.
• These functional connections correlate with interictal epileptic activity synchrony and seizure generation/spread.
• Findings aid in understanding epileptogenic networks in multiple heterotopic nodules and targeting treatment.