Distinct clinicopathologic subtypes of cortical dysplasia of Taylor

Background: Two pathologic subtypes based on the presence or absence of balloon cells have been described in cortical dysplasia of Taylor (CDT). Objective: To determine whether the pathologic subtype has any distinct clinical or MRI features that are relevant to management. Methods: The histopathologic, clinical, and MRI features of 34 children with CDT who underwent epilepsy surgery at Miami Children's Hospital from 1990 to 2001 were investigated. Results: Bizarre neuronal cytomegaly was the primary pathologic feature of 15 patients with the dysplasia-only subtype, and 19 cases showed additional characteristics including balloon cells and marked white matter abnormalities. Both groups presented with severe intractable epilepsy of very-early-onset, multiple daily seizures, cognitive disability, and focal neurologic deficits. The dysplasia-only subtype had higher rates of neonatal onset, hemiparesis, and severe mental retardation (p < 0.05). The MRI features of focal cortical thickening with associated cortical T2 signal change showed excellent sensitivity (94%) and reasonable specificity (73%) for the diagnosis of the balloon cell subtype. The overall surgical outcome was 59% seizure freedom at 2 years. Conclusions: Children with cortical dysplasia of Taylor type have in common a very-early-onset, severe epilepsy with neurologic co-morbidity. Patients with the non-balloon cell pathologic subtype have a more severe phenotype. A trend toward a better outcome in the balloon cell group suggests that preoperative identification of these subtypes may impact surgical planning.