A recent clinical trial has added to knowledge about what goes on in the body and brain when people with chronic low-back pain receive spinal manipulation (also known as spinal manipulative therapy). The researchers found that spinal manipulation, compared with placebo and no treatment, significantly reduced pain sensitivity. They also reported there was support for a potential biological target to address central sensitization of pain, a phenomenon of heightened pain sensitivity that is linked with acute pain’s transition to chronic pain, and the persistence of chronic pain. The research, supported in part by NCCAM and the National Center for Medical Rehabilitation Research, part of the National Institute of Child Health and Human Development, appeared in The Journal of Pain.

Researchers randomly assigned 110 adults aged 18 to 60 with chronic low-back pain to one of four treatment groups: actual spinal manipulation; a placebo consisting of a spinal manipulative sham procedure; an “enhanced placebo” that added to the sham procedure “instruction” of telling participants that the hands-on technique they would receive had been shown to significantly reduce low-back pain in some people; or no treatment. For the spinal manipulative and sham treatments, a licensed physical therapist delivered six treatments over 2 weeks.

Among the major findings was that pain sensitivity significantly decreased for the actual spinal manipulation group only and when measured with a protocol for suprathreshold (i.e., above-threshold) heat response. The findings indicate that a decrease in pain sensitivity is greater in response to spinal manipulative therapy than the expectation of receiving the therapy. Also, the enhanced placebo was found as believable a treatment as spinal manipulation and had the highest patient satisfaction of any group.

The researchers noted that areas for further study include whether the observed effects occur in acute low-back pain. They also suggested adding instruction to actual spinal manipulation to state that the therapy has been shown to significantly reduce low-back pain in some people.