As a live TV audience watches, a neurosurgery team at UH Case Medical Center in Cleveland will perform an operation that has helped many Parkinson’s disease patients get significant relief from their debilitating symptoms—tremors, rigidity, stiffness, slowed movements and difficulty walking—and also enabled them to reduce their amount of medication.
Deep Brain Stimulation, or DBS, was pioneered as a Parkinson’s treatment by Dr. Alim-Louis Benabid, a neurosurgeon who also possessed a Ph.D. in physics. In the 1980s, patients were treated by surgically destroying parts of their brains where tremors originated, or using medication with unpleasant side-effects. In 1987, Benabid was performing a surgery using the then-standard method of burning away brain tissue with an electrode. As he tested various regions with electrical pulses, Benabid wondered what would happen if he used different frequencies. To his surprise, he found one that suppressed the patient’s tremor. "I thought, aha, this might be the solution," he later recalled in a 2010 Lancet article.
Dr. Benabid’s inspiration led to the development of implantable DBS devices to provide patients’ brains with continual stimulation, which were approved by the U.S. Food and Drug Administration for use in treating Parkinson’s symptoms in 2002. Since then, thousands of patients have received DBS, and there are numerous surgical centers in the U.S. that perform the operation. While DBS initially was used as a last resort for the most severely-disabled patients, by the mid-2000s, doctors were using it to help patients with moderate symptoms, after they were unable to control the disease with medication.
Getting DBS is a complex process. Patients generally remain awake during the procedure so that surgeons can communicate with them and do neurological tests along the way and make sure the hardware is implanted in the right place. According to a primer published by the National Parkinson Foundation, the first step is to inject local anesthesia into a patient’s scalp, and then use screws to attach the patient’s head to a box-like frame that helps to guide neurosurgeons more precisely to the target. Then, the surgical team scans the patient’s brain with magnetic resonance imaging (MRI) or computed tomography (CT) to create a roadmap for the operation.
Once the team knows where they want to target, the patient’s scalp is injected with more anesthetic. Then a neurosurgeon uses a drill to bore a dime-sized hole in the patient’s skull. Then, the doctors insert a thin wire with four electrical contacts at its tip into one of several brain areas—the globus pallidus internus, the thalamus, or the subthalamic nucleus—that control movement.
At that point, the really delicate work begins. As electrical current is passed through the wire in the patient’s brain, the surgical team asks the patient to move his or her face, arm, or leg, or else moves them. They’re monitoring all of that activity with a computer, in an effort to pinpoint the exact spot where the tiny wire needs to be. Since surgeons are dealing with the brain structures that may only be a few millimeters in length, there’s precious little room for error.
After they’ve found the spot, they connect the wire to an external generator, and give the patient more stimulation to gauge the effect it is having on the Parkinson’s symptoms. Once they’ve confirmed that it is in the right place, they fasten it in place and then seal the hole in the skull and scalp with a plastic cap and stitches. The length of the surgery varies from hospital to hospital, but it often lasts as long as six hours.
After that—either immediately, or in a few days—a second procedure is performed, in which the wiring in the brain is attached through a patient’s neck to a pacemaker-like device called a neurostimulator, which they implant in the patient’s chest, just below the collarbone. When the device is turned on, it delivers electrical stimulation to the brain.
Exactly how DBS reduces Parkinson’s symptoms in some patients is not yet completely understood. One theory is that the electrical pulses given off by the DBS device stimulate neurons to fire, which makes them too busy to transmit the abnormal electrical signals triggered by the disease. But that hasn’t been proven, and scientists are at a loss to explain exactly why DBS works better for some patients than others.
Researchers continue to work to improve DBS in hopes of making it more effective. UH Case Medical Center’s team will utilize a digital visualization product created by a Cleveland-based company called Surgical Theater, headed by a former Israeli air force officer who once created flight simulators for fighter pilots. The simulator allows surgeons to create and explore 3D-models of patients’ brains. As an article in Crain’s Cleveland Business reports, Case surgeons also are interested in using Oculus Rift virtual reality headsets in the operating room, so that they can use the simulations to help guide an operation.
Meanwhile, medical researchers are looking at DBS to treat other brain illnesses, such as obsessive-compulsive disorder and treatment-resistant depression. So that operation which viewers will watch on “Brain Surgery Live” is one that could become increasingly common in the future.
Source : National Geographic channel