How brain stimulation gave chronic pain patients their lives back

Pam Belluck
Sometimes the pain felt like lightning bolts. Or snakes biting. Or needles. “Just imagine the worst burn you’ve ever had, all over your body, never going away,” said Ed Mowery, 55, describing his life with chronic pain. “I would wake up in the middle of night, screaming at the top of my lungs.”

Beginning with a severe knee injury he got playing soccer at 15, he underwent about 30 major surgeries for various injuries over the decades, including procedures on his knees, spine and ankles. Doctors put in a spinal cord stimulator, which delivers electrical pulses to relieve pain, and prescribed morphine, oxycodone and other medications, 17 a day at one point. Nothing helped.


Unable to walk or sit for more than 10 minutes, Mowery had to stop working at his job selling electronics to engineering companies, and stop playing guitar with his death metal band. Out of options four years ago, Mowery signed up for an advanced experiment: a clinical trial involving personalised deep brain stimulation to try to ease chronic pain. The study, published last month, outlines a new approach for the most devastating cases of chronic pain, and could also provide insights to help drive invention of less invasive therapies, pain experts said.

“It’s highly innovative work, using the experience and technology they have developed and applying it to an underserved area of medicine,” said Dr Andre Machado, chief of the Neurological Institute at Cleveland Clinic.
Chronic pain is defined as lasting at least three months, and it substantially limits daily activities. Some patients find relief in medication, nerve blocks or spinal cord stimulation, but doctors say these methods don’t work for many patients and have led to opioid addiction for some.

The study Mowery participated in was small, involving six patients with various types of long-standing chronic pain unrelieved by other treatments. But the trial was intensive and rigorous. Researchers implanted electrodes, identified brain areas and neural signals linked to individual patients’ pain, and then developed personalised algorithms using artificial intelligence that delivered bursts of stimulation when those signals surged.
Patients were followed for an average of 22 months, including a phase in which they randomly received either active stimulation or inactive sham stimulation, without knowing which.

The study found that personalised stimulation received in response to high-pain signals reduced average daily pain by about 60%. Sham stimulation, which can have placebo effects, provided almost no benefit. Patients reported that they could walk more, that their mood was improved, and that pain interfered less with their daily activities, sleep and enjoyment of life after personalised stimulation compared with sham.

One patient who had been virtually homebound, was able to travel and attend church and a family wedding. Since the trial, two patients have stopped taking all opioid and pain medications and two others, including Mowery, have markedly reduced their use of those medications.

Currently, deep brain stimulation is approved by the Food and Drug Administration for only a few conditions, including epilepsy and Parkinson’s disease. An author of the new study, Dr Prasad Shirvalkar, a neurologist at University of California, San Francisco, said deep brain stimulation had been briefly approved for chronic pain about 40 years ago, but approval was withdrawn a few years later because results were inconsistent. Some patients were not helped, while others found that their relief didn’t last. And solid data was limited because many studies did not compare active stimulation with sham stimulation, he said.

Pain is complex because it involves different interconnected brain areas, not one pain center, and because it has three neurological dimensions, Machado said: “What you feel, the sensation; how you understand it, which is cognitive; and how you process the emotion of it, the suffering.”

Reducing suffering, if not the pain itself, was one aim of the new study, said Dr Edward Chang, chair of neurological surgery at UC San Francisco and a senior author. Another goal was a better understanding of how the brain varies between patients, said Chang. Shirvalkar said the trial showed that personalised stimulation “is possible and that you can implement it in a way that actually helps people, but it’s not proof that it’s necessary.” Additional studies are planned, he said.
Unless it can be done more simply, the invasiveness and expense might make it inaccessible for many patients, experts said. “I think it does have potential, but we don’t quite know what that potential is,” said Dr Alex Green, a professor of neurosurgery at Oxford.

Still, Chang said, the devices and procedures may eventually become as accessible as cardiac pacemakers, and that by identifying pain biomarkers such research could “unlock many other therapies, both pharmacologic and stimulation-based.”

NYT news service