SAN FRANCISCO — Infants with intractable seizures and normal imaging results may have focal cortical dysplasia that can be detected by serial high-resolution MRI, Dr. Herman Tse said in a poster presentation at the annual meeting of the American Association of Neurological Surgeons.
Identifying and resecting focal cortical dysplasia can significantly decrease seizures in patients who do not respond to other therapies, said Dr. Tse, of Oregon Health and Science University, Portland, and his associates.
He described the case of a 12-month-old boy with multiple episodes of partial seizures whose EEG results showed the seizure onset to be focused in the brain's right hemisphere but whose CT and MRI results were normal. Treatment with multiple anticonvulsant medications failed to improve the patient's seizures.
Repeat MRI studies at 13, 23, and 30 months of age revealed progression of a right posterior frontal lesion with increased signals on T2-weighted images and fluid-attenuated inversion recovery (FLAIR) MRI. These findings and disruption of the gray-white junction were consistent with focal cortical dysplasia, said Dr. Tse.
At age 30 months, the infant underwent staged cortical mapping and resection of the lesion with the aid of subdural grid placement and stereotactic navigation, he said. Pathology showed large, bizarrely shaped dyslaminated neurons with nodules of cortical dysplasia. The surgical resection caused no complications and reduced the frequency of seizures by more than 90%.
Focal cortical dysplasia, a type of cortical development malformation first described in 1971, is a common cause of pediatric intractable epilepsy. During infancy, as the cerebral cortex undergoes significant development, MRI may be normal initially in infants with intractable partial epilepsy, especially if the focus of seizures is located in areas of late myelination.
Therefore, serial imaging, especially with high-resolution MRI, may be helpful, particularly in infants under 18 months of age with intractable seizures, said Dr. Tse.