Focal cortical dysplasia: Molecular disturbances and clinicopathological classification (Review)

Area of Science:

• Neurology
• Neuroscience
• Pediatric Epilepsy

Background:

• Focal cortical dysplasia (FCD) is a leading cause of pediatric drug-resistant epilepsy, especially in children under three.
• Despite decades of research since its initial description, the precise mechanisms underlying FCD-related cortical abnormalities remain unclear.
• The International League Against Epilepsy (ILAE) has proposed a new classification system for FCD.

Purpose of the Study:

• To review current knowledge on clinical and histopathological aspects of FCD, incorporating the new ILAE classification.
• To analyze clinicopathological associations and surgical outcomes across different FCD subtypes, distinguishing isolated FCD from FCD with principal lesions.
• To summarize genetic findings, potential epileptogenesis mechanisms, and novel factors contributing to drug resistance in FCD.

Main Methods:

• Literature review of clinical, histopathological, and genetic studies on Focal Cortical Dysplasia.
• Analysis of the International League Against Epilepsy's new classification system for FCD.
• Comparative evaluation of FCD subtypes and their association with principal lesions and surgical outcomes.

Main Results:

• The review synthesizes current understanding of FCD subtypes, highlighting clinicopathological correlations and surgical outcomes.
• Genetic studies suggest potential mechanisms for cortical dysregulation and drug resistance in FCD.
• A comparison between FCD type IIB and tuberous sclerosis-associated brain tumors is presented, exploring a potential link.

Conclusions:

• Understanding FCD subtypes and their underlying mechanisms is crucial for improving epilepsy treatment in pediatric patients.
• Further research into genetic factors and novel epileptogenic mechanisms may lead to targeted therapies for drug-resistant epilepsy.
• The hypothesis that FCD type IIB may represent a localized manifestation of tuberous sclerosis warrants further investigation.