A DMC neurosurgeon uses EEG and brain surgery to treat adult epilepsy - Part I of a two-part series.
Decoding Epilepsy, Part I: What, Where, How
In 2007 David King, a registered nurse from Traverse City, Michigan, experienced his first symptoms of epilepsy.
“It happened so fast,” says David, “Essentially I lost contact with who I was, where I was, what was going on. It seemed like the world was spinning but not moving at the same time.” David was having epileptic seizures, a condition where some neurons in the brain emit abnormal electrical impulses. These “misfires” can cause a variety of symptoms.
Ordinarily, the brain operates by sending signals between electrically excitable cells called neurons. It does this to control muscles and also to process information. It’s not completely understood why neurons can start to misfire. Some known causes include brain tumors, brain infections and injuries, and malformed blood vessels in the brain. However some epilepsies have no obvious physical cause. Whatever the reason, if groups of neurons begin to misfire and emit abnormal signals the effect can spread, normal functioning is interrupted, and seizures can occur.
Most of us think of seizures as uncontrollable convulsions. The typical image most people have of an epileptic seizure is of the victim’s entire body shaking uncontrollably, but that is only one of many possible responses to abnormal neural activity. Dr. Sandeep Mittal is a neurosurgeon and head of the epilepsy and brain tumor surgery program at the Detroit Medical Center.
“There are 40 or 50 different types of seizures,” reports Dr. Mittal. “They range from small partial type of seizures or the big convulsions or, more generalized seizures.” What David King experienced was a complex partial seizure. Over the next few days they became increasingly severe, with David becoming completely unresponsive for minutes at a time. David was hospitalized in Traverse City, Michigan. Doctors tried anti-seizure medication without success. They suspected a brain tumor was the cause of the epilepsy, but they did not offer much in the way of comprehensive treatment options.
Frustrated, Dave’s wife Edwina began searching for specialist, a search that led her to the Detroit Medical Center’s DMC Harper University Hospital and Dr. Mittal.
Dr. Mittal determined that David did, in fact, have a large tumor in the left temporal lobe of his brain. He ordered extensive testing including an observation procedure called a scalp electro-encephalogram, or EEG. For this test, David was hospitalized for several days while his brain activity was monitored with electrodes placed to his head and his seizures were videotaped.
Dr. Mittal explains why: “So we can go back and review the seizure itself – the video part and what happens to him at the time, as well as the EEG, so we can figure out which part of the brain the seizure is coming from.” The testing revealed that David’s epilepsy was coming from his left temporal lobe, the same part of the brain where his tumor was located.
Dr. Mittal devised a two-stage treatment process: First, to precisely locate both the neuron clusters that were misfiring and the critical areas of David’s brain; and second, to use surgery both to remove the tumor and to correct David’s epilepsy, while minimizing any potential risk of side effects due to the surgery.
Having determined that David is a good candidate for Surgery, Dr. Mittal and his team proceed with Stage one of the repair procedure. It involves placing sensors on David’s brain to gather more precise information about the source of his seizures. Dr. Mittal will then know what portion of the left temporal lobe to remove to stop the seizures.
Why is it okay to lose portions of your brain? What do you lose along with it? Dr. Mittal answers: “I always like to say that every part of the brain is very important, but luckily some parts are less important than others. You know, epilepsy surgery is sometimes referred as functional neurosurgery, which means that we want to preserve and improve function rather than take away. Typically for our epilepsy patients their quality of life a lot of times dramatically increases after surgery. So in a sense, patients are better not having abnormal brain than to have that in place.”
As part of his pre-operative testing, David had a detailed MRI taken of his brain. It is, in effect, a roadmap for the surgical team as they examine the brain tissue.
Dr Mittal uses a probe connected to a computer to locate points on David’s head. The computer uses technology similar GPS, the global positioning system, to superimpose the probe’s location on David’s head with the MRI image of David’s brain. This allows the doctors to see exactly where they are relative to David’s brain at all times. “The tip of this probe points to exactly where we are on the brain…in terms of…here’s the Frontal Lobe, on the left side…here we’re getting closer to the eye…and behind the eye is the Temporal Lobe…and you can see where the bright spot is where the tumor is.”
Dr. Mittal uses the probe to locate and mark the incision lines on David’s head, and then the surgery begins.
With David prepped, Dr. Mittal makes the incision and exposes the skull. As traumatic as this looks, when replaced the skin will reattach to the skull and heal normally. Having exposed the skull, Dr Mittal now cuts a window in it to access the brain. He uses the GPS system to ensure he’s made the hole large enough.
Underneath the skull is a delicate, thin membrane called the Dura. Carefully cutting trough it, he exposes the brain itself. Dr. Mittal visually inspects the brain and compares what he sees to the MRI image. “This is a very critical region, that we actually call the ‘central area’ because it’s physically in the center, with motor in front, sensory in the back.”
He then determines the appropriate electrodes, and places them on the surface of the brain.
At this point, Dr. Mittal has covered the frontal lobe, part of the parietal lobe, and the temporal lobe, even underneath the temporal lobe, with a grid of electrodes that will allow his team to know what is going on inside the brain. Finally he places two depth electrodes inside the tumor and in the hippocampus, the area suspected of causing the seizures.
With all the electrodes in place, the team tests them to ensure that they’re getting good information. Dr. Mittal can already see some activity. “Already we see some epileptic activity, or spiking as we call it, here. This area seems to be potentially an area where the seizures are either coming from or spreading to.”
Finally, Dr. Mittal closes David’s head. With the electrodes in place, the patient will spend another four days in continuous monitoring.
In our final segment, we will show you how Dr. Mittal puts the collected data to use to stop David’s seizures, and later, we will meet Mary Borchardt who has also undergone this procedure with Dr. Mittal. She will tell us how the surgery worked for her.
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