Research used neuroimaging techniques to analyze the brains of more than 3,800 volunteers in different countries. The largest study of its kind ever conducted set out to investigate anatomical similarities and differences in the brains of individuals with different types of epilepsy and to seek markers that could help with prognosis and treatment. The study was published in the journal Brain.

Epilepsy's seizure frequency and severity, as well as the patient's response to drug therapy, vary with the part of the brain affected and other poorly understood factors. Data from the scientific literature suggests that roughly one-third of patients do not respond well to anti-epileptic drugs. Research has shown that these individuals are more likely to develop cognitive and behavioral impairments over the years.

A differential study

According to the researcher, advances in neuroimaging techniques have enabled the detection of structural alterations in the brains of people with epilepsy that hadn't been noticed previously. The analysis covered both patients who had had epilepsy for years and patients who had been diagnosed recently. According to Cendes, the analysis and they aimed at the identification of atrophied brain regions in which the cortical thickness was smaller than in the control group.

First analysis

The researchers first analyzed data from the four patient subgroups as a whole and compared them with the controls to determine whether there were anatomical alterations common to all forms of epilepsy. "We found that all four subgroups displayed atrophy in areas of the sensitive-motor cortex and in some parts of the frontal lobe," Cendes said.

"Temporal lobe epilepsy occurs in a specific brain region and is therefore termed a focal form of the disease. It's also the most common treatment-refractory subtype of epilepsy in adults," Cendes said. They know it has different and more severe effects when it involves the left hemisphere than the right.

When the left hemisphere is involved, the seizures are more intense and diffuse. It used to be thought that this happened because the left hemisphere is dominant for language, but this does not appear to be the only reason. Somehow, it's more vulnerable than the right hemisphere.

Future developments

From the vantage point of the coordinator for the FAPESP-funded center, the findings published in the article will benefit research in the area and will also have future implications for the diagnosis of the disease.

They know there are specific signatures of the different epileptic subtypes, instead of looking for alterations everywhere in the brain, they can focus on suspect regions, reducing cost, saving time and bolstering the statistical power of the analysis. Next, they will be able to correlate these alterations with cognitive and behavioral dysfunction.