Why You Need to Know What Part of the Brain Causes Seizures

Where do seizures start in the brain?

It’s important to know what part of the brain causes seizures in order for your doctor to identify treatment options. The types of seizures fall into two main categories: focal seizures or generalized seizures.

Focal seizures, previously called partial seizures, usually start in a specific area of the brain. Sometimes, they spread to other regions of the brain. With the right diagnostic tests, you can find out the part(s) of the brain where your seizures begin.

What type of seizure affects both sides of the brain?

Generalized seizures affect both sides of the brain. Sometimes the seizure activity seems to start from a network of regions and quickly spreads to the entire brain. Other times, the seizures happen throughout your whole brain, at once. Generalized seizures can include absence seizures (previously known as petit mal seizures) and tonic-clonic seizures (previously called grand mal seizures).

Parts of the brain involved in seizures

Your brain has four main parts, or lobes, that are mirrored on both sides of the brain. Seizure activity can start within any of these lobes during focal seizures, or involve all of them during generalized seizures:

• Frontal lobe: The frontal lobe is the front part of your brain. It’s responsible for speech and movement. It’s also associated with more complex abilities, such as reasoning, planning, and problem solving.
• Temporal lobe: The temporal lobe is on the side of your brain. It’s involved in processing sound and emotions, understanding language, recognizing faces, and planning movement. Deep within the temporal lobe sits the hippocampus, which is essential for long-term memory and learning.
• Parietal lobe: The parietal lobe is at the top of your brain. It’s associated with perception and awareness of your body and surroundings. It combines information from each of your senses to coordinate your movements in response.
• Occipital lobe: The occipital lobe is at the back of your brain. It’s responsible for sight and processes all the information that your eyes send to this area of the brain.

What is a seizure focus?

A seizure focus is the place where your seizures begin in the brain. Focal seizures may also start in two or more places, called seizure foci. Generalized seizures don’t have an identifiable starting point, but focal seizures do.

For example, Tyler’s seizures start in her right temporal lobe near her speech center. In fact, many focal seizures begin somewhere in the temporal lobe.

When you have a focal seizure, your first symptoms tend to map to the area of the brain where the seizure started. In Tyler’s case, she started stuttering and had trouble using her left hand. These symptoms make sense, given the temporal lobe’s role in language and movement.

How your seizure focus determines your treatment

Medication can work well for many people with generalized or focal seizures. But about 40% of people with epilepsy — more than 1 million Americans — still have seizures despite taking medication. When you have drug-resistant epilepsy, learning more about your seizure focus can help you find more effective treatment.

For example, you may discover that your seizures originate from a part of the brain that can be safely altered. Your doctor might recommend resective surgery (removing the area) or laser ablation (destroying the area with heat from a laser). Without the area of the brain responsible for seizures, many people experience freedom from seizures after these procedures.

On the other hand, your seizures may start in an area essential for language, movement, or memory. In this case, you could benefit from treatment using a neurostimulation device. Neurostimulation can help manage your seizures by delivering electrical pulses to your brain. These pulses don’t harm brain tissue or interfere with your abilities, such as speaking or moving.

Ricky decided to get responsive neurostimulation (the RNS System®) after learning more about his seizure foci. “After testing, they found that I was having seizures from a focus on both sides of my brain,” Ricky says. The RNS System offered a way to treat both foci with direct stimulation instead of tissue removal.

Ouida wasn’t a good candidate for epilepsy surgery, either. Her seizures came from the left hippocampus.

“They told me that any resective surgery carried too great a risk of damaging both my speech and memory capabilities,” Ouida explains. “We talked about how RNS could be a great option because the RNS would target my seizure area in the hippocampus, and we could avoid doing a resection.”

But as the RNS System gathered data over time, Ouida’s doctor learned exactly where her seizures started. This information allowed Ouida’s surgeon to safely get rid of that area of her hippocampus using heat (a procedure called laser ablation).

Getting a comprehensive epilepsy evaluation

So how do you learn what part of the brain causes your seizures, like Tyler, Ricky, and Ouida did? The first step is finding an epileptologist (epilepsy specialist) at a comprehensive epilepsy center. These doctors work with a team of other experts to learn more about your seizures.

They aim to pinpoint the place in your brain where the seizures begin using a combination of epilepsy tests, such as:

• Electroencephalogram (EEG) monitoring, which uses electrodes (small metal discs) all over your scalp to record your brain electrical activity, including what happens when a seizure occurs.
• Computerized tomography (CT) scan, which combines several X-ray images to create a three-dimensional view of your brain and any abnormalities
• Magnetic resonance imaging (MRI), which creates highly detailed images of your brain using magnetic fields
• Neuropsychological testing, which checks your mental abilities, such as attention, memory, and information processing

Sometimes you need more advanced tests, such as intracranial monitoring, to learn about your seizures. These tests can include stereotactic electroencephalography (SEEG), which temporarily puts depth electrodes (long flexible wires) in different areas of your brain to record seizure activity.

Finding the right treatment approach for your seizures

When you have a better understanding of your seizures, you have more insight into what treatments fit your needs. The results of a comprehensive epilepsy evaluation allow you and your doctor to personalize your epilepsy treatment. That might mean adjusting medications, choosing a surgical option such as resection or neurostimulation, or using a combination of treatments. In any case, you’ll know that you’re aiming treatment toward the right part(s) of your brain.