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MRI used to predict language impairment before surgery

9 July, 2003

Researchers have shown for the first time that it is possible to use Magnetic Resonance Imaging (MRI) scanning to predict when patients undergoing brain surgery will develop problems with language functioning.

The finding, published in the journal Neurology, was the result of research conducted over the past eight years at the Medical College of Wisconsin at Froedtert Hospital and supported by the National Institutes of Health.

The research involved scanning over 60 patients with temporal lobe epilepsy. In the study, the researchers wrote that many patients with this type of epilepsy require surgical removal of part of the temporal lobe to stop the seizures from recurring. Studies show that as many as 50 per cent of patients develop mild language problems, mainly difficulty with fluent recall of words, when the surgery involves the left temporal lobe.

Dr Jeffrey Binder, professor of neurology at the Medical College, said:

"If the language areas in... the temporal lobe are concentrated on the left side of the brain, the risk of developing language problems after surgery is high compared to when the language areas are spread equally between the left and right temporal lobes.

"We found that by using fMRI we could predict, with a high degree of accuracy, which patients showed a significant decline in word retrieval abilities."

In the fMRI test, the patients lie on their back in an MRI scanner and perform language tests while brain images are taken. Areas of the brain that are actively involved in performing the language tests become brighter on the image due to increased blood flow to the active area.

Dr Binder added:

"This development has enormous significance for patients with temporal lobe epilepsy. For the first time, these patients will have a fairly precise idea of how the surgery will affect their language abilities, allowing them to more accurately weigh the risks and benefits of undergoing surgery."

The predictive ability of the fMRI test was shown to be better than another brain mapping technique, the Wada test, which is done routinely in such cases to assess the risk of postoperative language and memory problems, according to Dr Binder. The Wada test, which has been in use for over 40 years, requires inserting a catheter into the body and therefore carries a small risk of complications.

The Medical College researchers hope one day to replace the Wada test with fMRI, if adequate fMRI methods for predicting memory outcomes can be developed. They plan to continue developing and testing fMRI methods for predicting memory change after surgery, but for now they will continue performing both tests; using fMRI to assess the risk to language areas and the Wada test to assess the risk to memory areas.