Epilepsy surgery is an option for patients with intractable partial onset seizures that are not controlled by oral medications. Epilepsy monitoring is used to localize the seizure focus, often a lesion or abnormal area of brain located in the temporal lobe. That part of the brain is then carefully removed to prevent future seizures:
Left temporal lobe resections are more risky that right-sided cases, because the left hemisphere controls language functions in most (even left handed) patients. Surgeons have to be very careful planning seizure surgery on the left side to be sure that they do not damage brain critical for speech and language and leave the patient with aphasia.
That’s where functional magnetic resonance imaging (fMRI) comes in. fMRI goes beyond the conventional imaging of brain structure, and can actually localize regional brain functions by detecting changes in regional blood flow in response actual or imagined activity.
fMRI is increasingly being used to evaluate candidates for epilepsy surgery by identifying important functional regions within the brain, including unpredictable patterns of functional reorganization, to prevent unexpected post-operative deficits. Click here for a link to a paper with illustrative cases.