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Brain Stimulation Lets PD Patients Live a Life
Volume 15, Number 2
Banker John Kellerman thought it odd that his left hand shook as he carried a bag of groceries. His wife, a nurse practitioner, shrugged it off, as the shaking soon stopped. But after the tremor reappeared, she worried. And at 38, Kellerman found himself saddled with Parkinson's disease, traveling the route of improvement on Sinemet and other drugs, then gradual decline as the disease outruns their ability to help.
Eight years later, Kellerman had learned to cram his living into dwindling "on" times while enduring "off" ones-periods of rigidity and slowness or inability to move. Worse, his "on" times were increasingly disrupted by drug side effects: "The dyskinesias are awful and unpredictable," says Kellerman, referring to involuntary twisting movements-the last straw in isolating PD patients from society.
Thus Kellerman became a Hopkins candidate for deep brain stimulation (DBS), a technique the FDA approved last spring to diminish Parkinson's tremor, slowness and gait problems. As a benefit, DBS also dramatically cuts dyskinesia. A recent New England Journal of Medicine report cites a jump in patients' dyskinesia-free "on" period, on average, from 27 percent of waking time before the procedure to 74 percent a half year later.
Moreover, says neurosurgeon Frederick Lenz, M.D., Ph.D., veteran of 196 DBS surgeries, the technique whittles down many patients' drug needs: "They can function on less. One or two have gone off drugs altogether."
In DBS surgery, Lenz and his team plot a path to the appropriate spot in patients' brains to stimulate-usually the subthalamic nucleus. Locating the nucleus is a careful, high-precision process, and the awake patient plays an active role in helping pinpoint the target. Then, with the patient anesthetized, Lenz inserts and anchors a small electrode connected to a pacemaker-size neurostimulator he implants below the clavicle. "The stimulation blocks the ability of target basal ganglia to fire," Lenz explains, "as though they've been lesioned." Once patients recover from surgery, telemetry allows clinicians to fine-tune stimulation frequency, distribution and voltage.
"DBS is by no means a cure," says neurologist Stephen Grill, M.D., Ph.D., who, as part of the Hopkins team, assesses patients for surgery and fine-tunes the stimulator, "but it returns a rich measure of patients' lives." Some say it's like turning the clock back 10 years on their disease.
Part of the success, says Grill, lies in patient screening. "You choose patients who no longer improve on medication, whose motor symptoms fluctuate and who have clear dyskinesia." Also, patients who can't tolerate PD drugs or whose incapacitating tremor won't respond to them may be candidates.
For Kellerman, who had DBS implanted in his right subthalamic nucleus (STN), followed by the left a year later, dyskinsia greatly diminished while his balance and gait significantly improved.
A bit abashed, he says that after adjusting to his increase in ability, "I got spoiled. I focused on what I still couldn't do." But when Kellerman's DBS accidentally shut off for two weeks --something that can't happen now-- his consciousness was raised: "I was literally on my hands and knees, unable to move. The DBS makes a real difference in my life."
For more information, call 410-955-8795.