When Govea underwent the procedure in 2003, a small hole was drilled in his skull, and an electrical wire -- about the thickness of a strand of spaghetti -- was inserted into a small area called the subthalamic nucleus, part of the complex basal-ganglia system associated with steady muscle control. The wire was then connected to a battery pack, which generates a pulsing electrical current. Doctors implanted the battery in his abdomen in a separate operation (it's now typically placed under the collar bone).
"It is the predominant way people get surgical treatment for P.D. these days," said Dr. Chad Christine, a neurologist at UCSF, who is lead author of a forthcoming study on the technique.
The electrical stimulation alleviates the symptoms of Parkinson's disease, though no one knows exactly how. The most basic answer is that deep brain stimulation is setting up an interference pattern for abnormal electrical activity in the brain. "Like a jamming mechanism," Christine said.
Electrical firing patterns are abnormal in patients with Parkinson's disease. The subthalamic nucleus is firing too frequently, and its pattern is erratic, causing the motor system to go on the fritz. Deep brain stimulation could either be interfering with this activity or, alternatively, "reasserting a more normal rhythm to this part of the brain ... a more normal firing pattern," Christine explained. Some scientists think the data indicate that its effects are even better than that. To meet Govea is to see why.
Four years after his surgery, Govea's symptoms are still under control. "Look at my hand," he said, holding it perfectly still. He takes his own pills now, and he can read the newspaper without tearing it apart. Deep brain stimulation has "just changed my whole life," he said.
That's the irony of Govea's story. Advancements in the understanding of Parkinson's disease were made possible by the discovery of MPTP, which was made possible by Govea's fateful dosing with the drug. It also led to the development of deep brain stimulation. In essence, Govea has received a treatment developed from research done with the very chemical that gave him the disease being treated.
Sometimes Govea still finds himself sitting on his hands, or walking with them pressed against his sides -- reminders of a time when his shaking was uncontrollable. Govea is still incarcerated at Atascadero, but he is no longer plagued by the side effects of his medications or the symptoms of his disease. In that sense, at least, he is a little closer to being free.