The clinical manifestations are closely related to the particular frontal lobe regions from which the seizures originate. As with our patient, frontal lobe complex partial seizures are frequently misdiagnosed as psychogenic seizures. The association between heterotopia and seizures has long been recognized. With better resolution and newer image techniques, MRI can identify subtle forms of cortical dysplasia in patients with presumed cryptogenic seizures. This may be especially true in patients with frontal lobe epilepsy.
Several studies suggest enhanced epileptogenicity of dysplastic cortex in animals and humans.
3-5 Heterotopia are clusters of neurons in abnormal locations as a result of arrested radial migration. Certain features make subependymal heterotopia an entity distinct from other neuronal migration disorders, including female predominance, mild clinical symptoms, normal development, and seizure onset during the second decade of life. We believe our patient falls into this category. Heterotopia may be nodular or diffuse, isolated or associated with other anomalies, and are more often bilateral than unilateral. On MRI they are isointense with gray matter on all imaging sequences, and do not alter intensity with contrast media.