The center's experimental device, manufactured by the company Medtronic, is different from other such devices on the market. It helps control the tremors by turning on the stimulation only when a patient moves his or her arms. Research suggests that intermittent stimulation may do a better job of treating symptoms, said UW neurosurgeon Andrew Ko.
And because the device isn't running constantly, its battery is expected to last longer -- an important consideration, since changing the battery in an implanted device requires surgery.
So far, just four patients have had the experimental device implanted, as part of a clinical trial that runs through the end of 2018. The researchers are looking for ways to expand the trial.
The device works this way: Neurosurgeons implant sensors in the brain, where they gather data from the motor cortex -- the part of the brain necessary for voluntary movement -- and detect when a patient is moving his or her arm.
In order to make this work, the CSNE team had to develop machine learning algorithms that "decode" those neural signals coming from the brain and correlate them with essential tremor symptoms.
"When the system detects arm movement, it turns on stimulation that is directed at a different part of the brain," said Ko, who did Foy's surgery. "That stimulation treats the patient's tremor. In some ways, it is like a prosthetic device for brain pathways."
Researchers are also exploring whether patients could consciously adjust the device. A side effect of deep brain stimulation is that it makes it difficult to speak clearly. The researchers hope patients could one day control the device's on-and-off switch just by thinking about it, rather than turning the device on and off manually.
Foy said he went through physical therapy to make sure he was a good candidate for the surgery, and while he was in the sessions, he discovered how many things he could no longer do. The realization brought him to tears.
"I didn't realize how bad a shape I was in," he said.
Now, he goes to the UW every month to participate in research on how the device is working for him. He had the surgery to fix the tremors in his right hand; his left hand still trembles, and he also walks with a cane.