Epilepsy surgery can be a lifesaving measure for children with intractable epilepsy. But even when the surgery is successful at curing epilepsy, it can introduce language impediments and other cognitive issues. Several tests try to predict how surgery might affect a person’s language ability.
Functional magnetic resonance imaging (fMRI) is the preferred way to determine if a brain area targeted during surgery is the same area that the child relies on for language or speech. During an fMRI scan, the child is asked to complete tasks that activate different parts of the brain, sending oxygen to these areas. The fMRI machine then measures these changes in oxygen and displays them as a map so that the surgeon can see which areas of the brain are active during each task. This helps the surgeon determine where the edges of brain surgery should lie to avoid tampering with healthy brain tissue. Because slight movements can throw off the fMRI scanner and produce blurry images, some tasks may need to be repeated.
An fMRI scan is less expensive and less likely to cause injury than other predictive tests, such as Wada (intracarotid amobarbital test). But fMRI predicts only language skills while other tests can predict both language and memory. With regards to language prediction, fMRI is about as accurate as Wada. fMRI has successfully predicted language function after surgery in people with medial temporal lobe epilepsy, temporal epilepsy in general, and extratemporal epilepsy. However, fMRI is less accurate in people with temporal neocortical epilepsy or temporal tumors.
Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology
Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy. Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology