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Discerning Seizure-Onset v. Propagation Zone: Pre-and-Post-Operative Resting-State fMRI Directionality and Boerwinkle
Varina L Boerwinkle1, Bethany L Sussman2, Sarah N Wyckoff2
1Division of Pediatric Neurology, University of North Carolina, Dept. of Neurology, 170 Manning Dr, CB #7025, Chapel Hill, NC 25714, USA.
Neuroimage. Clinical
|June 2, 2022
Summary
This study shows resting-state fMRI effective connectivity accurately distinguishes seizure onset zones from propagation zones in children with epilepsy. This method can help identify epilepsy origins and improve treatment outcomes.
Area of Science:
- Neuroscience
- Medical Imaging
- Epileptology
Background:
- Distinguishing seizure onset zones (SOZ) from propagation zones (pZ) is crucial for epilepsy surgery.
- Resting-state functional MRI (rs-fMRI) offers a non-invasive method to assess brain connectivity.
- Effective connectivity analysis, specifically using dynamic causal modeling (DCM), can reveal directed interactions between brain regions.
Purpose of the Study:
- To evaluate the capacity of rs-fMRI effective connectivity (RSEC) to differentiate SOZ from pZ in pediatric patients with hypothalamic hamartoma (HH) and drug-resistant epilepsy (DRE).
- To validate the accuracy of RSEC, particularly the Directionality method, in identifying excitatory and inhibitory connections between SOZ and pZ.
- To explore the relationship between RSEC, surgical outcomes (Engel class), age, and seizure reduction.
Main Methods:
- Cross-spectral dynamic causal modeling (DCM) was employed to estimate RSEC between the SOZ and pZ in pediatric epilepsy patients undergoing surgery.
- Parametric Empirical Bayes (PEB) group analysis was used to assess group effects, outcomes, and age-related associations with RSEC.
- Pre- and post-operative RSEC were compared to evaluate surgical impact.
Main Results:
- RSEC accurately identified the expected excitatory SOZ → pZ and inhibitory pZ → SOZ connections in 96% of cases, achieving high sensitivity (95%) and accuracy (88%) in differentiating SOZ and pZ.
- Better surgical outcomes (Engel Ia) correlated with stronger inhibitory pZ → SOZ connectivity.
- Post-surgery, RSEC showed diminished excitatory and inhibitory modulation, consistent with successful ablation of epileptogenic tissue.
Conclusions:
- rs-fMRI effective connectivity, particularly using the Directionality method, is a validated and accurate tool for identifying the origin of excitatory and inhibitory signals in pediatric DRE associated with HH.
- This approach holds potential for refining SOZ localization in other DRE populations and neurological disorders.
- The findings support the utility of RSEC in pre-surgical planning and understanding epilepsy network dynamics.
Keywords:
Effective connectivityEpilepsy surgeryHypothalamic hamartomaResting state functional MRISeizureSurgical candidacy
