Detection of heterotopic gray matter in children by magnetic resonance imaging.

Heterotopic gray matter results from abnormal brain development and is a recognized focus of seizures. It may be associated with mental retardation and/or severe malformations of the brain. Three patients with heterotopia of gray matter were identified by magnetic resonance imaging (MRI). CT failed to detect the heterotopic gray matter in each case. One child was referred for removal of a neoplasm based on CT studies until MRI demonstrated the developmental nature of his condition. One infant had severely dysplastic left cerebral hemisphere associated with heterotopic gray matter and the syndrome of Hypomelanosis of Ito. All three children suffered from seizures and/or mental retardation. MRI provided important information in the management of each case and appears to be the imaging method of choice in evaluating children with seizures or retardation for heterotopic gray matter in the brain.