One in four U.S. adults suffer from chronic pain, many from chronic pain that is resistant to treatment. People with conditions like post-stroke pain, phantom limb pain, nerve pain and pain from spinal injuries are often left with in agony but little hope for relief.
That could change as deep brain stimulation (DBS) goes from a way to treat motor diseases to a possible treatment for chronic pain – treatment that can be customized to the patient’s brain makeup and their own brain’s feedback.
“Never before have patients with chronic pain had the opportunity to walk around and deliver neural data in real time,” said Prasad Shirvalkar, MD, PhD, assistant professor of Anesthesiology at UC San Francisco. “We’re at the front edge of trying to open up new indications for DBS.”
DBS already is used to treat movement disorders, like Parkinson’s disease, dystonia and essential tremors. Patients have electrodes implanted deep into the parts of their brain that control movement, and receive electrical current via a stimulator put into their chest.
The problem with current DBS treatment is that the electrical current is constant. It doesn’t take in feedback or adjust based on what’s really happening in the brain. Patients can suffer side effects like trouble speaking and change in personality – even seizure or stroke. Their brains can also become acclimated to the treatment so that it doesn’t work anymore.
Shirvalkar – along with Edward Chang, MD, and Philip Starr, MD, PhD, professors of Neurological Surgery and members of the USCF Weill Institute for Neurosciences – have received a $7.56 million, five-year grant from the National Institutes of Health (NIH) to improve DBS as a treatment for chronic pain. It’s one of 10 grants worth more than $40 million that UCSF researchers have been awarded as part of the NIH Helping to End Addiction Long-Term (HEAL) Initiative.
Instead of providing a continuous current, this grant is helping researchers make the electric charge more customized by first identifying new targets for stimulation, and creating systems that can take feedback from the brain and adjust the device accordingly.
“When we find those new targets, the next goal is identifying brain biomarkers of chronic pain for each patient,” Shirvalkar said. That means recording direct from patients’ brains while they experience natural pain fluctuations. “By combining their neural signals with their pain reports, we’re trying to build a model of how their brain represents pain.”
Shirvalkar likens current DBS to what they hope for to a space heater versus a thermostat. A space heater “provides constant heat. You might get too hot and then have to turn it off,” he said. “A thermostat is feedback controlled heating. We are trying to build a model to serve as a thermostat to control electronic stimulation to provide pain relief.”
The grant started in October 2019, and Shirvalkar said they are still enrolling patients. The grant includes funding for travel, so patients do not need to live in California. Those interested in being part of the trial can contact the Pain Management Center at [email protected].