Doctors at Children’s hope to improve surgery for seizures and epilepsy by using clinical advances and research into new imaging techniques.
Functional MRI Imaging
During surgery, we carefully avoid harming key areas of the brain, such as those important for language. Sometimes, this limits what we can do during surgery.
“Brain mapping” is the standard way of finding important areas in the brain. To map the brain, electrodes have to be placed on the surface of the brain. Then, we run tiny amounts of electrical current on the child’s brain to identify specific areas that control functions such as movement and language.
Dr. Jeffrey G. Ojemann and his team are studying a specific type of brain mapping procedure called functional Magnetic Resonance Imaging (fMRI) to better show these key areas in the brain. We hope fMRI will improve surgery for seizures.
Functional MRI identifies the brain’s language areas. Sometimes these must be found while a child is awake. Brain mapping (second image) finds the language areas.
Standard brain mapping is done in one of two ways:
- We place electrodes on the child’s brain and record our findings for a few days. We pass currents through the electrodes and temporarily disrupt brain activity. By seeing which areas that are affected, we can learn which parts of the brain we need to avoid in surgery.
- In the operating room, we wake the child up during surgery and briefly block brain function in specific areas with a small electrical current. This doesn’t hurt the child because the human brain does not feel pain.
We are beginning to use fMRI as another way of brain mapping. During an fMRI scan, we’ll ask the child to do something, such as tap his finger, look at pictures, read or listen to words.
This allows us to see which parts of the child’s brain are being used during these activities.
Currently, this is used only with older children and we continue to use standard brain mapping. Someday, we may be able to rely only on fMRI.
Questions and Answers with Dr. Jeffrey G. Ojemann About fMRI
Dr. Jeffrey G. Ojemann
Q: What is the goal of fMRI research?
A: We want to learn if fMRI can help us find the important areas of the brain we identify by brain mapping.
Having this information will help us avoid those important brain areas while still being able to operate on problem brain tissue.
Q: Are there other functions such as language, memory or personality that can be mapped?
A: We know language is very complicated. Some language tasks are used for brain mapping and seem to keep surgery safe.
But we know that language involves reading, understanding, speaking in words and sentences and many other things that we take for granted. We need to know more about how epilepsy and surgery for epilepsy interacts with language abilities.
Memory is even more complicated. Seizures, seizure medicine and surgery can all impair memory. Memory for something you just saw and memory for distant things, like where you keep your favorite toy, are different.
We would like to know how epilepsy and treatment for epilepsy impacts these different types of memory. Our research is trying to find out how the brain deals with memory in the face of epilepsy.
Personality and other things that are very important to who we are cannot be easily mapped onto one part of the brain.
Although surgery can impact a child’s behavior, the effects of seizures and seizure medicines seem to play an even greater role in determining how epilepsy affects behavior and how a child deals with the things and people around them.
Flumazenil Positron Emission Tomography (flumazenil PET)
In a research study, flumazenil PET shows where seizures begin even when an MRI is normal.
Dr. Jeffrey Ojemann and his research team are working on a research study involving a promising new type of imaging that may show the source of seizures when MRI cannot.
A flumazenil positron emission tomography (flumazenil PET) targets certain proteins called GABA receptors. There may be an abnormally low number of them in the parts of the brain where the child’s seizures begin.
We are trying to learn if flumazenil PET images can show abnormalities in children with seizures that cannot be controlled by medicine, also known as intractable seizures.
Questions and Answers with Dr. Jeffrey Ojemann About Flumazenil PET
Q: What are GABA receptors?
A: These receptors in the brain shut down (quiet) nerve cells. The fewer GABA receptors a child has, the harder it is to do this.
Q: What causes a low number of GABA receptors in a child’s brain?
A: We do not know yet. We think certain congenital disorders may lead to an abnormal number of GABA receptors.
Q: What is the main goal of flumazenil PET research?
A: These images will help make surgery safer and more exact, especially when other tests don’t give us many clues.
Q: Are children involved in fPET studies?
A: Children have not been involved in this study yet. However, we are preparing a clinical study that will involve children.
When it begins, we will be the only medical facility in the United States doing this kind of clinical trial. Our goal is to determine if this procedure is helpful to children with intractable seizures.