Previous large studies have suggested that epidural steroid injections provide some short-term alleviation of radiating pain associated with disc herniations or spinal stenosis. Since a disc herniation has a natural history of improvement, it’s reasonable to consider epidural steroid injections to suppress symptoms while the body heals itself. Of course for other conditions which seem to progressively worsen with time, injections may be less beneficial. There is a need for new analgesics, which are non-narcotics, to help treat this pain.
Chronic low back pain may not respond well to injections. Studies suggest that certain proteins circulate in the blood increasing the sensitivity of the nervous system to pain. Nerve growth factor (NGF) is a protein our bodies secrete to serve many functions, with one being sensory nerve maintenance. Pain receptors are particularly dependent on NGF. Rats infused with NGF have heightened pain compared to normal rodents. In humans, elevated NGF levels are detected in chronic pain conditions. For years, antibodies designed to destroy NGF have been developed in the laboratory to treat chronic pain. For unclear reason, it’s never translated into a very successful treatment.
A new study in the journal, Pain, suggests that an antibody to NGF, Tanezumab, improved chronic pain in some patients. Participants had chronic low back pain without relief from at least three different types of pain medications, including opioids. They had imaging verification of degenerative arthritis of their spines. Individuals receiving a subcutaneous injection of Tanezumab every 8 weeks had significantly improved pain compared to control groups. 43% had more than 50% pain improvement at 16 weeks into the trial, compared to 37% in the control group. Further studies will be performed to determine dosing prior to a possible release to the general public. Studies like this highlight the multifactorial components of chronic pain not well addressed currently. Endless injections, elevated doses of opiates, or even surgery may not be the best solution for certain chronic pain patients.
Markman J et al. Tanezumab for chronic low back pain. A randomized, double-blind, placebo- and active-controlled, phase 3 study of efficacy and safety. Pain. May 2020.