Flipping the Switch
on Parkinson's Disease
Some diseases that disable the body are actually rooted in the brain. Take Parkinson’s disease, for example. In this common neurological disorder, the brain loses its natural ability to produce a chemical that transmits electrical impulses. The flow of electricity within the brain becomes irregular, causing shaking in the arms and legs, slowness of movement, muscle rigidity and difficulty balancing.
| What if you could locate irregular electrical flow in the brain and turn it off — like flipping off a light switch? A recently approved procedure available at Froedtert & the Medical College of Wisconsin allows physicians to do something like that. The procedure is called deep brain stimulation. For patients with Parkinson’s disease and other movement disorders, it can provide significant relief from debilitating symptoms. In the future, it could give new hope to people with seizure disorders and even psychological problems. |
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For a 56-year-old man from Crivitz, Wis., deep brain stimulation has reopened the door to normal life.
In 1993, Wayne Beno, then working as a machine operator in Green Bay, underwent surgery to relieve neck pain. When he awoke after the procedure, his arm was shaking. At first, Wayne thought it was an effect of the operation. Months of consultations, however, pointed to a different cause. At age 43, Wayne was diagnosed with Parkinson’s disease.
Over the next decade, his symptoms gradually grew worse. “The whole right side of my body would shake,” he says. “My arm shook; my head shook. My wife, Sandra, had a hard time sleeping, because I was shaking in bed.” Once an avid hunter and fisherman, Wayne found it harder to take part in outdoor activities: “I couldn’t make a knot or tie a hook.” Doctors increased his medications, but the relief they provided diminished steadily.
According to movement disorder experts, Wayne’s story is typical. Most patients with Parkinson’s disease take levodopa, a medication that replaces the neurotransmitter dopamine they can no longer produce naturally. The problem is that the effectiveness of levodopa decreases with time. Initially, the drug might offer six hours of symptom relief — or “on” time. Gradually,“on” time recedes to five hours, three hours, maybe only an hour and a half. In addition, the drug causes side effects of nausea and a condition called dyskinesia — jerking and fidgeting movements that can be similar to the symptoms of Parkinson’s. Patients experience wide fluctuations in symptoms throughout the day, with the window of relief getting smaller and smaller.
“You have to work your life around times when the medication is at maximum,” Wayne says. His medication use eventually climbed to 30 pills a day. “I was constantly getting sick to my stomach from pills.” Finally, last spring, Wayne became aware of an alternative. “My doctor heard about deep brain stimulation and said he thought I should look into it.” Wayne’s next stop was Froedtert & the Medical College of Wisconsin.
Jamming the Flow
Deep brain stimulation (also known as DBS) is like a pacemaker for the brain. Surgeons implant an electrode in the area of the patient’s brain where symptoms originate. The electrode is connected to a battery device placed under the skin at the collarbone. When turned on, this device provides gentle electrical stimulation to brain tissue surrounding the electrode. “The stimulation effect of DBS is complex,” says Bradley Hiner, MD, Medical College of Wisconsin neurologist. “It jams the abnormal signals of neurological disease and allows the brain to function more normally.”
Dr. Hiner and Brian Kopell, MD, Medical College of Wisconsin functional neurosurgeon, are co-directors of the Restorative Neurosciences Program at Froedtert & the Medical College of Wisconsin. Dr. Kopell also leads the DBS surgical team. In addition to Parkinson’s disease, Drs. Kopell and Hiner say deep brain stimulation is highly effective in treating essential/familial tremor, as well as other movement disorders like dystonia and Tourette syndrome. Even cluster headaches have responded favorably to DBS. “The common denominator for all these diseases,” Dr. Kopell says, “is that we can locate the network in the brain where the problem is coming from, and we can target a specific area in that network precisely with DBS.” He points out that medications can’t pinpoint those targets without affecting other brain regions. As a result, they often cause unwanted side effects.
When the Restorative Neurosciences team began working with Wayne, one of the first steps was to evaluate his medication response. “We want to see how good a patient’s ‘on’ is,” Dr. Hiner says.
“Generally, deep brain stimulation does not get you any better than your best ‘on’ — it just gets you more ‘on’ with less medication and fewer side effects.”
To gauge drug response, a physician evaluates a patient after he or she has been off levodopa for 12 hours. The patient then takes a normal morning dose. An hour later, he or she is re-evaluated for symptom improvement. Known as “off-on testing,” this technique helps predict how well a patient will respond to DBS.
During the “off ” portion of his evaluation, Wayne shook excessively. The “on” test showed a strong medication response. These and other assessments confirmed Wayne as a good candidate for deep brain stimulation.
Static and Music
The DBS operation is different from most other surgeries in that patients are awake during much of the procedure. Why? Because feedback from the patient helps surgeons know when the electrode is in the right place.
During the procedure, the patient receives strong topical anesthetics and sedatives. Intravenous agents are used to bring the patient in and out of consciousness as needed. Since it is important that the skull remain perfectly still, the head is immobilized within a frame attached to the surgery table.
Dr. Kopell accesses the patient’s brain through a hole in the top of the skull. Guided by MRI imaging, he advances a thin tube called a cannula through tissue toward the brain structure where the disordered symptoms originate. Inside the cannula is a microelectrode that, at its tip, measures just millionths of an inch. When the cannula is close to the target, Dr. Hiner deploys the microelectrode. As the probe advances, it picks up the “white noise” of brain electricity. “Every area of the brain has a distinct electrical signature,” Dr. Kopell says. When the microelectrode is positioned correctly, the sound is unmistakable. “To the untrained ear, it sounds like static,” he says. “To the trained ear, it’s music.”
When the target is located, the surgical team withdraws the probe and inserts a permanent electrode, a wire about the thickness of a strand of spaghetti. The procedure is often performed twice — once on each side of the brain. The team checks placement several times during surgery by talking to the patient and assessing responses to test stimulation.
Wayne has a vivid memory of one of these moments. “All of a sudden, my arms and legs stopped shaking,” he recalls. “I said, ‘Holy cow, I’m paralyzed!’ Then the doctor asked me if I could move my toes.” Wayne moved his toes. “Then he said, ‘Well,Wayne, I just turned the stimulator on. Congratulations.’
“The shaking went away instantly. It was indescribable.”
Hopeful, but Realistic
While proper placement of the electrode is key, it is not the only factor in a successful outcome. Chris Sheridan, RN, Restorative Neurosciences Program manager, says proper follow-up is essential. “It can take a couple of months to adjust the stimulation to the optimal level and get the medication dosage right.”
Sheridan adjusts patients’ neurostimulators using a wireless handheld device. Since the tip of the electrode has a number of different contacts, Sheridan can also adjust the size and shape of the stimulation field.
Patients also receive a wireless control for turning the neurostimulator on and off. “It’s nice, because if a patient who lives 200 miles away calls and says his tremor is back, I can direct him or her to turn the stimulation up,” Sheridan says.
Most patients who undergo DBS benefit from rehabilitation. “Patients with Parkinson’s disease become deconditioned, because they haven’t used their muscles in a long time,” John McGuire, MD, Medical College of Wisconsin physical medicine and rehabilitation specialist says. Rehabilitation for DBS patients can include physical, occupational and speech therapy, as well as psychological counseling. “We see what the patient’s goals are — whether it is simply walking better, performing activities of daily living or getting back to woodworking,” Dr. McGuire says.
Some DBS patients, notes, do not need rehabilitation at all. “For some, it’s like turning on a light switch and everything is back to normal — it has been amazing.”
More Than I Expected
Two weeks after his first procedure, Wayne went back to surgery for the implantation of his battery pack. Two weeks later, his permanent stimulator was activated for the first time. “When it was turned on,” Wayne says, “I stopped shaking completely.”
Wayne’s recovery from his surgeries took several weeks, and finding the right stimulation setting took months. His relief from symptoms, however, has been remarkable. He needed no rehabilitation and is completely off medication.
With appropriate patient selection, the vast majority of patients who undergo DBS experience significant improvement. “On each end of the spectrum are outliers,” Sheridan says. “Best of all is the occasional patient who no longer needs medication and you can’t tell they have a movement disorder.” Most patients are able to cut their medication dosage in half and experience smoothing out of their responses. “However, not everyone is a candidate for DBS,” Dr. Hiner says, “and our goal in the selection process is to identify those individuals who have a high probability of having a successful outcome.”
How long does the beneficial effect of DBS last for people with Parkinson’s disease? “We are pushing patients back up the ramp maybe five or 10 years,” Dr. Hiner says. “DBS is not a cure for Parkinson’s; it is not getting at the root cause of the disease.”
On the other hand, he notes patients suffering from a condition known as essential tremors can expect more.“ At least one-third of patients with essential tremors do not respond to any medications,” Dr. Hiner says. “The benefit of DBS for these patients is extraordinary — it is almost a cure for some.”
Most DBS patients have a safe outcome. Still, there are risks, including the possibility of stroke, infection, or hardware failure. Sheridan notes that, nationwide, one or two percent of DBS patients need to return to surgery to have their electrodes re-positioned.
Astonishing Possibilities
The list of conditions physicians can treat with DBS and related technologies includes chronic pain — and that list will grow. "If we can locate the cause of a problem in the brain," Dr. Hiner says, "there is no reason we can't modulate the activity with these technologies."
Neuromodulation technologies could provide treatment for epilepsy in the future. In addition, Dr. Kopell says clinical trials are already beginning to tackle psychiatric disorders, including severe depression and obsessive-compulsive disorder. Treatment to address autism, addictions and even eating disorders may be just around the corner.
According to Dr. Kopell, advances in imaging technology could make the surgery itself easier for patients. “Within five years, functional imaging may allow us to do the surgery without having the patient awake.”
Unbeatable Rewards
For the members of the Restorative Neurosciences team, providing treatment is personally rewarding. “You learn something every time you go into the OR,” Dr. Kopell says. “An unbeatable part of the experience is seeing patients light up when their symptoms are turned off. This is a great thing to be a part of.”
Wayne Beno feels much the same way. “The doctors said the best I could probably expect was to reduce medications by 50 percent and cut the shaking by 80 percent,” he says. “But for me it was 100 percent. I hardly shake now and I take no pills at all. I would do it again — that’s for sure.”