As the fetal brain develops, new neurons are born and migrate to different parts of the brain, forming the complex and highly ordered structure of the cerebral cortex. But every now and again, that process goes awry. Sometimes tiny architectural glitches in the cortex lead to big problems, such as the uncontrolled electrical storms in the brain that underlie seizures.
Now higher-resolution brain-imaging technologies could help doctors find these hidden flaws, allowing surgeons to remove the damaged area – and giving scientists new insight into the causes of epilepsy.
Epilepsy is characterized by recurring seizures, caused by uncontrolled waves of electrical activity that propagate throughout the brain. About two-thirds of epilepsy patients can control the disease with drugs. The remaining third can sometimes undergo surgery to remove the tiny section of brain tissue that sparks seizures – but only if surgeons can find the offending spot with a brain scan.
Scientists estimate that about 25 percent of these patients have tiny abnormalities – which likely originated during cortical development – that are too subtle to be detected with traditional brain imaging. But new imaging technologies, such as those being developed by researchers at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital (MGH) in Boston, are bringing relief to these patients. In a study released last fall, Ellen Grant, chief of pediatric neuroradiology at MGH, and colleagues were able to detect lesions in about two-thirds of epileptic patients whose previous brain scans had been declared normal, making these patients better candidates for neurosurgery. The team is now engineering even higher-resolution devices, which they’ll use to study learning disabilities and other developmental disorders, such as autism.
“This technology is a very good improvement over previous high-resolution technologies,” says Imad Najm, an epilepsy expert at the Cleveland Clinic in Ohio. “It will allow us to see some lesions we did not see before and to see bigger lesions where we could see only smaller ones, lesions which were just the tip of the iceberg.”
With traditional magnetic resonance imaging (MRI), a large magnet is coupled with a radio-frequency detector that picks up characteristic signals from different tissues in the brain, generating a detailed picture of the brain’s structure. Scientists are now developing devices that use arrays of anywhere from 8 to 256 detectors to get higher-resolution images of the brain. “It’s like a compound eye for MRI,” says Bruce Rosen, director of the Martinos Center.