Experimental Brain Implant Gives Long-Term Relief from Chronic Pain
/By Crystal Lindell
An experimental brain implant that detects when someone is in pain and responds by stimulating the brain with tiny electrodes provided long-term relief from chronic pain, according to a small new study led by researchers at the University of California, San Francisco (UCSF)
The preprint study, which has not yet been peer-reviewed, involved six patients with severe chronic nerve pain that did not respond to conventional treatment. The patients were hospitalized for 10 days so that researchers could put temporary electrodes in their brains to target areas involved in pain processing with deep brain stimulation (DBS).
Of the six patients, five had clinically meaningful pain relief. Those five patients then had the experimental DBS implants permanently placed in their brains. Over the next six months, brain activity and pain signals were recorded to create a personalized “map” of each brain
The system then used each patient’s unique brain signals (pain “biomarkers”) to decide in real time when to turn the low frequency stimulation on or off. Referred to as “closed-loop DBS,” the implants did not run continuously, but automatically adjusted when pain was felt and turned off when patients were asleep.
Patients were also given sham placebo stimulation in brain areas outside the ideal location to serve as a comparison..
The closed-loop DBS system worked better than the placebo treatment. Researchers say they identified several brain areas that gave quick pain relief when stimulated, and that they could accurately predict people’s pain levels just from their brain activity.
On average, the DBS implants reduced pain intensity by 50 percent, while the sham treatment increased pain levels. Patients also were able to walk further after real stimulation – their step counts rose by 18 percent – compared to just one percent with sham treatment. For some patients, the benefits lasted over three years.
“In five participants, we observed acute, rapid pain relief which translated into long-term efficacy after permanent closed-loop DBS for up to 3.5 years,” researchers reported. One patient who suffered from chronic pain after a stroke experienced “profound and durable pain relief.”
The implant surgeries, however, were not trouble free. Two participants experienced serious adverse events related to surgery, but continued in the trial and experienced no serious adverse events related to stimulation.
“Our study is limited by a small sample size, constraining the generalizability of these findings to other chronic pain syndromes. Although we observed initial evidence of sustained benefits up to 3.5 years, additional follow up is required to monitor for late-emerging tolerance,” researchers concluded.
Previous attempts to use deep pain stimulation for pain relief have been “inconsistent with poor long-term results.” Those prior attempts, however, used a one size-fits-all-approach and did not target specific brain regions for each patient, as the UCSF study did..
DBS is being used to treat movement disorders associated with Parkinson’s disease, tremors, and other neurological conditions. It is also used to manage some psychiatric conditions. DBS is considered a treatment of last resort for patients that don’t respond well to medications or have severe side effects from them.
