Medtronic’s new Activa PC+S DBS device combines stimulation therapy with brain sensing and recording, allowing physicians to download brain activity data that could be used to monitor treatment and advance research into neurological disorders.
Researchers hope that the technology may eventually shift to a feedback-controlled system, in which treatment is tailored to the individual patient and stimulation triggered by abnormal brain rhythms, rather than continuously as DBS systems do now. A closed-loop DBS system could revolutionize the way doctors treat Parkinson’s disease, essential tremor and even, 1 day, depression, obsessive-compulsive disorder or memory impairments, Starr told MassDevice.com.
Starr, professor of neurological surgery and surgical director of UC San Francisco’s Bachmann-Strauss Dystonia and Parkinson Foundation Center of Excellence, was 1 of 2 surgeons who were the 1st in the U.S. to implant the new Activa PC+S system. The device’s inaugural procedures were conducted in patients with advanced Parkinson’s disease, and researchers are able to selectively monitor and record targeted areas of the brain. The 1st global implant was conducted in Germany in August.
In an interview with MassDevice.com, Dr. Starr highlighted the research value of feedback-controlled DBS and talked about the near and distant future applications for the technology.
MassDevice.com: What is the general state of deep-brain stimulation, and what makes the Activa PC+S system so special?
Dr. Philip Starr: Deep-brain stimulation has been a pretty simplistic kind of stimulation therapy. It’s been an open-loop device, meaning it just delivers a current continuously and is not responsive to changes in the brain or changes in patient symptoms.
The new Activa PC+S device is a big step toward changing the way DBS works. It is a device that delivers all of the standard therapeutic stimulation but also has capability of sensing and storing brain electrical activity that can be downloaded non-invasively. By studying the brain’s electrical activity we can, in a future step, use that to do automatic control of the brain stimulator to make it responsive to the varying needs of the brain and the patient’s symptoms.
MassDevice.com: Initial implants were given to Parkinson’s patients, but what other conditions may benefit from this technology?
Dr. Philip Starr: Right now deep-brain stimulation is a standard therapy for a number of movement disorders, like Parkinson’s disease, tremor disorders and dystonia, which is a common movement disorder. It’s standard for those. It’s being investigated for a wide variety of other applications, including mood depression and memory disorders. Those are still investigational. What is basically holding back the field, in terms of exciting new developments in DBS, is the relative crudity of the stimulation algorithms.
If you think of heart pacemakers, those are very sophisticated. They sense abnormal heart rhythms and when they sense an abnormal rhythm they selectively abort that rhythm. These DBS devices are basically brain pacemakers, but they’re where heart pacemakers were back in the ’60s. They are just on all the time without sensing capability. By developing brain sensing, for which this new active PC+S is a big step, the importance is that it will develop a device that’s responsive to the brain.
Right now it works pretty well for Parkinson’s, but as you move into other disorders, like mood depression, which are much more difficult to assess objectively, what someone’s mood is, it’s going to be very important to have devices that recognize the abnormal brain rhythm underlying the disorder and then use that rhythm to selectively alter the brain to get rid of the bad activity.
I look at the development of this Medtronic brain recording system, Activa PC+S, as a step that could potentially benefit Parkinson’s therapy but, probably more importantly, it will hopefully start to allow more rapid development of these newer applications like mood depression.
MassDevice.com: What are some of the advantages of selective, rather than constant, stimulation?
Dr. Philip Starr: Because it’s on all the time, it has a high current drain which results in large battery size and rapid draining of the batteries and greater side effects. The more current you use, the more it’s going to spread to [brain] circuits that it doesn’t need to affect, and that produces side effects. I think an advantage of closed-loop stimulation is smaller batteries, lower current and lower side effects.
MassDevice.com: Federal groups have taken an interest in closed-loop DBS as well. What are they looking for?
Dr. Philip Starr: The [Defense Advanced Research Projects Agency] is interested in funding research that will greatly improve the understanding of circuits underlying psychiatric disorders, especially those common in military veterans, and then both developing the understanding of the brain circuitry and then developing miniaturized devices with wireless transmission that will improve those disorders.
That’s a big deal, that DARPA grant, lots of it’s very competitive, lots of groups are going for it.
MassDevice.com: How close are we to a closed-loop DBS system?
Dr. Philip Starr: In terms of using it for a fully closed-loop or fully feedback-controlled system, that’s soon. The device already, I think, has some capabilities to do that in a limited way, so I would say certainly within the next 2 or 3 years.
The Activa PC+S device actually has some capabilities within it to auto-detect detect brain events and change programming. It also has the ability to interact with an external computer non-invasively so that brain data can be streamed to a computer and analyzed in any way that is desired, and then the computer can be used to auto-control the device.
So even now, with Activa PC+S, there are possibilities for doing feedback-controlled stimulation. It is likely going to be done through an external computer until the technique is worked out and then the technique can be internalized in the next generation of devices.
This interview has been edited for content and clarity.