Focal cortical dysplasia - review

Area of Science:

• Neurology
• Neuroscience
• Medical Imaging

Background:

• Focal cortical dysplasia (FCD) is a primary cause of medically refractory epilepsy, particularly in pediatric populations, and a significant cause in adults.
• Pathogenesis involves both genetic and acquired factors, with several classification systems proposed over time.
• Three main types of FCD are recognized, differing in clinical presentation, severity, and typical age of onset.

Purpose of the Study:

• To review the classification, pathogenesis, and diagnostic imaging of focal cortical dysplasia.
• To highlight the role of MRI and other advanced neuroimaging techniques in identifying FCD and guiding treatment decisions for drug-resistant epilepsy.

Main Methods:

• Review of existing literature on FCD classification and diagnosis.
• Analysis of common and advanced neuroimaging findings in different FCD types.
• Discussion of the utility of MRI, FDG PET, MEG, DTI, and intracranial EEG in diagnosis and management.

Main Results:

• FCD Type I often presents with mild symptoms and temporal lobe involvement, while Type II shows more severe symptoms, typically in children, with extratemporal and frontal lobe predilection.
• MRI reveals abnormalities in most Type II and some Type I FCDs, including cortical thickening/thinning, gray-white matter blurring, and T2/FLAIR hyperintensities.
• MRI can be normal in Type I FCD or underestimate the seizure-generating region, necessitating supplementary imaging techniques.

Conclusions:

• Accurate diagnosis and localization of FCD are crucial for surgical planning in drug-resistant epilepsy.
• While MRI is valuable, advanced techniques like FDG PET, MEG, DTI, and intracranial EEG are essential for comprehensive evaluation.
• Continued advances in genetics and neuroimaging promise improved understanding and treatment of FCD-related epilepsy.