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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.

Conventional cortical stimulation based on pulses of fixed duration briefer than the chronaxie rarely elicit responses in infants and young children. We developed a stimulation paradigm that relies on increments in both stimulus intensity and pulse duration. This approach ensures that stimulation parameters converge to the chronaxie by mathematically minimizing the energy required to elicit a response. In six patients, this paradigm successfully elicited clinical responses and/or afterdischarges at thresholds 5-8 mA below the standard paradigm and at up to 64% lower energy levels. Furthermore, three patients under age 5 years who did not respond to maximal fixed duration stimulation demonstrated afterdischarges and clinical responses when longer pulse durations were utilized. These findings indicate that a paradigm based on dual increments is effective for cortical mapping in children. Furthermore, by ensuring responses at lower energy levels, it may be more efficient for mapping the cortex at all ages.