Imaging Spectrum of Cortical Dysplasia in Children

Abstract

estimated that up to 30% of patients become resistant to optimized medical therapy and are potential surgical candidates. 2 Criteria for this distinction have varied, but most agree that failure of 2 appropriate antiepileptic drugs to adequately control seizures, with more than one seizure/month over an 18-month–2-year period, constitute intractability. 2 Additional important clinical features indicating that the patient may be a surgical candidate include stereotyped, lateralizing seizures with focality of semiology, a localized “epileptogenic zone” by scalp electroencephalography (EEG), magnetoencephalography (MEG), or surface EEG, and a localized anatomical target on magnetic resonance imaging (MRI). 2 In fact, the presence of an imaging abnormality is one of the key findings that predict resistance to medical therapy and may be a critical finding in determining suitability for surgical therapy. 3 Interestingly, it is thought by many pediatric epileptologists that younger children may in fact be better candidates for epilepsy surgery than adults because of their increased neuroplasticity and the detrimental effect of repeated seizures on normal neurologic development. 4 Cortical dysplasia is the most common neuropathology noted after surgical resection for intractable epilepsy in children, and recent clinicopathologic classification systems have had a significant effect on the treatment and understanding of this disorder. 5,6 Some forms of focal cortical dysplasia (FCD) (such as type IIb) have typical imaging manifestations, whereas other types such as isolated type I cortical dysplasia have variable and often nonlocalizing imaging features. As imaging findings indicating cortical dysplasia may significantly affect selection for potential surgery, radiologists involved with the workup of these patients must be familiar with the imaging spectrum of FCD, especially in children. In this article, we review the current pathologic classification and imaging findings in cortical dysplasia with an emphasis on the pediatric population.