Personalized brain stimulation can ease chronic pain

Mapping a woman’s pain in her brain allowed scientists to turn it down. A small case series, published July 30 in Brain Stimulation, indicates that even stubborn, complex pain signals may be disrupted when the right spot is stimulated with electricity.

Unlike acute pain from a broken arm, some pain continues long after healing. Chronic pain, produced by changes in the brain and spinal cord, is particularly difficult to treat. “We have been limited in what we can do for these patients, and they have a great deal of suffering,” says neurosurgeon Michael Lim of Stanford University School of Medicine. The findings open a new way to treat this kind of pernicious pain, says Lim, who was not involved in the study.

One approach to treating chronic pain involves targeting the brain directly with deep brain stimulation, or DBS. The method relies on electrodes on thin wires implanted in the brain and a battery pack implanted in the chest. DBS is most commonly used to treat Parkinson’s disease, and it is being studied for effectiveness in other conditions, including depression.

So far, tests of DBS for chronic pain have produced inconsistent outcomes, working for some people but not others. That unevenness might relate to the complexities of pain that originates from changes in the brain itself. The experience of pain is assembled by collections of brain networks, including those handling sensory input, chemical signals and even emotional components, says Vivek Buch, a neurosurgeon and neuroscientist at Stanford University. “And somehow they’re coming together as an integrated signal to give a person a perception of pain.”

Adding more complexity, each person’s brain may process things differently. Chronic pain, as well as psychiatric disorders such as depression and obsessive-compulsive disorder, “are just not one-size-fits-all,” Buch says.

The study’s premise was simple: first, map a person’s particular collection of pain signals. Then, once that map is drawn, deliver small, precise electrical signals to scramble the pain signals and, ideally, provide relief.

Buch and his colleagues recruited three people, all of whom had severe and chronic face pain. These volunteers underwent surgeries in which clinicians inserted temporary electrodes through small holes in the skull into key brain regions. Over the next three days, researchers systematically sent small blips of electricity through these wires to different spots in the volunteers’ brains.

This mapping produced specific information about each person’s pain, says Karl Deisseroth, a neuroscientist, psychiatrist and Howard Hughes Medical Institute investigator at Stanford. “Finding out, for a particular person, the location, the pattern of stimulation that helps that person is crucial for determining what definitive treatment might work.”

Results varied among the three people. One volunteer did not get much relief from any combination of stimulation; two people’s pain improved.

One participant, a woman in her 40s, went on to have four permanent electrode wires implanted in the regions of her brain that responded positively during testing. Six and 12 months later, she is still feeling better. “She’s doing really great,” Buch says. “She sends us text messages routinely.” The second woman, who had relief during testing, plans to get a permanent implant soon, Buch says.

The person who did not experience much relief from electrical stimulation still taught the researchers a lot. Successful outcomes are important, Deisseroth says, “but it’s just as important to identify if the definitive treatment is not going to work.”

“To have an objective measure guiding whether or not you take someone through a particular course of treatment, that’s a dream in psychiatry and psychiatry-adjacent fields and disorders,” Deisseroth says. “And so to see this work, and to be able to guide us [to] who should get a treatment, is just a very important step for the field.”

Looking ahead, the researchers hope to study more conditions with this brain-mapping approach, both as a therapeutic effort and as a way to learn more about how the brain works. “From my perspective in psychiatry,” Deisseroth says, “I don’t know that there’s a ceiling on where we can go.”