Parkinson's, a neurodegenerative condition, is characterized by symptoms such as muscle stiffness and tremor in the limbs, as well as impaired balance, all of which tend to worsen over time. Has innovative research found a more reliable tool that helps to improve these symptoms?
Available treatments for this condition target its symptoms, aiming to improve the patients' quality of life.
These treatments include different types of drugs that may focus either on motor on non-motor effects of the disease, as well as deep brain stimulation, which may be offered as an alternative therapy to people who do not respond well to drugs.
In deep brain stimulation, electrodes are surgically implanted into the brain. These are connected to a device that is attached to the chest. Through these implants, electrical stimuli are transmitted to the regions of the brain that regulate movement.
However, deep brain stimulation has — at least so far — come with certain risks and drawbacks. The device works continuously and has to be programmed so that the stimuli it sends are best adjusted to the wearer's needs.
Often, devices will need to be reprogrammed by a specialist. Also, because they run on batteries, the lifespan of these implants is limited, and they eventually have to be replaced.
A team at the University of California, San Francisco — whose work was supported by the National Institute of Neurological Disorders and Stroke (NINDS) — recognizes these drawbacks and set out to test more personalizable deep brain stimulation implants.
The results of their efforts — which were part of the Advancing Innovative Technologies (BRAIN) Initiative — have been reported in the Journal of Neural Engineering.
A new type of brain stimulation implant
The researchers tested a type of implant that responds and adjusts to signals from the brain that are related to the symptoms experienced in Parkinson's disease. Not only does it register these inputs, but in doing so, it also adapts to deliver appropriate stimulation as needed.
"This is the first time," explains study author Dr. Philip Starr, that "a fully implanted device has been used for closed-loop [non-constant], adaptive deep brain stimulation in human Parkinson's disease patients."
The project was a short-term feasibility trial, in which two people with Parkinson's agreed to receive this fine-tuned, adaptable deep brain stimulation implant.
In this trial, the implant was programmed to monitor the brain for signals related to dyskinesia — or involuntary movements — which sometimes occurs as a side effect of deep brain stimulation.
So, when the device picked up signs of dyskinesia, it reduced stimulation to the brain. On the other hand, when no dyskinesia was detected, the stimulation was increased. This strategy was calculated to decrease the side effects related to this type of therapy.
The trial's results indicated that this type of implant was no less effective in reducing Parkinson's symptoms than traditional deep brain stimulation.
Also, since this device is adaptive and does not send out stimuli constantly, the researchers noted that it saves approximately 40 percent of the battery energy that would normally be consumed during traditional, open-loop brain stimulation.
Because these tests were only carried out over a short period of time, it was not possible for the investigators to establish exactly how the innovative implant performed, compared with more traditional brain stimulation devices, when it comes to instances of dyskinesia.
However, due to the new implant's adaptability, the researchers are hopeful that the closed-loop stimulation device would fare much better in this respect and possibly lead to fewer adverse effects.
'An important first step'
Also, Dr. Starr explains, "Other adaptive deep brain stimulation designs record brain activity from an area adjacent to where the stimulation occurs, in the basal ganglia, which is susceptible to interference from stimulation current."
"Instead," he goes on, "our device receives feedback from the motor cortex, far from the stimulation source, providing a more reliable signal."
The researchers are excited about the avenues that this feasibility study is opening up in terms of improving Parkinson's therapy, and they are already planning larger trials in order to test the device's long-term effectiveness.
"The novel approach taken in this small-scale feasibility study may be an important first step in developing a more refined or personalized way for doctors to reduce the problems patients with Parkinson's disease face every day."
Nick B. Langhals, program director at NINDS
You can watch Dr. Starr's explanation about the innovative brain stimulation devices in the video below.