CT-Guided Pain Relief Could Be Lasting -- With No Side Effects

Chronic and acute severe pain is debilitating and hard to treat. The strongest pain relievers for this pain, opioids, are highly addictive and interfere with motor function. Radiology has relieved the pain of millions of patients through CT-guided interventions like steroid and anesthetic injections. But these solutions don’t work for everyone, and they don’t last long. Patients often require repeated injections before experiencing sustained pain relief.  

Now, UCSF researchers are one step closer to finding and destroying pain with targeted, lasting relief and no side effects.

In a study published September 16 in the journal Science Translational Medicine, a research team led by UCSF Department of Radiology professors Jacob Brown, MD, PhD, and William P. Dillon, MD, used CT-guided needles to target TRPV1 pain receptors in swine test subjects with resiniferatoxin (RTX), a variant of capsaicin. Capsaicin is the chemical that gives chili peppers their kick.

“RTX is 1,000 times stronger than the hottest chili pepper you could ever eat,” said Dillon. But instead of causing a painful reaction like chili can, RTX kills pain and painful reactions to heat. “It’s been injected into the spinal canal to treat pain in cancer patients, but we wanted to see if it could more selectively cause pain reduction. Targeting TRPV1 receptors makes sense because it is almost exclusively found on pain-transmitting neurons.”

During the 4-week period after RTX injections were made, test subjects were administered low-level laser stimuli to gauge their reaction to pain and heat. The subjects consistently showed no or delayed pain response. Their motor function was also tested and appeared not to be affected.

“This technique could translate into sustained pain relief that does not interfere with daily activities,” remarked Brown. “That the procedure stops pain and doesn’t affect ‘bystander’ nerves which govern motor function is further proof that the more we know about the molecular mechanism of pain, the more precisely we can provide pain relief.”

“We are hopeful that we, along with collaborators at other institutions, can rapidly transition this technique to human trials. There is great promise here for people who suffer from arthritis, herniated disks, sciatica, and pain that can’t be treated by other methods,” said Dillon.