Chronic low back pain is an issue contributing significantly to the burden of disease around the world. This fact isn’t a new or surprising one. But as the study of pain and its impact on the brain moves forward, we are discovering increasingly that pain alters the brain in many different ways. It is no surprise that many of these changes are pain related but that’s not where the story ends. We have also seen literature that indicates diminished activity in the prefrontal cortex of the brain (the area responsible for executive function) and the cerebellum (which controls movement and speech) in recent years. But what happens in the brain after spinal manipulative therapy is a very interesting thing indeed.
Research emerging from chiropractic research has yielded promising evidence in recent history, but a recent study published in the journal “Frontiers in Integrative Neuroscience” adds weight to the growing evidence bank that spinal manipulation changes the brain. It was a clinical trial, and a longitudinal study at that, which used fMRI (functional Magnetic Resonance Imaging) to see what was going on in the brain before and after Spinal Manipulative Therapy (SMT) was administered to patients with chronic low back pain.
The study took place over 7 months and took in patients with chronic low back pain who had no pharmacological or physical therapy interventions (including SMT) in the month prior. Exclusion criteria was applied to ensure the validity of the study. What makes this study quite interesting is that Group 1 (the treatment group) was recruited first and then Group 2 was recruited so they could match the participants in terms of age and sex to act as the healthy control group. Their brain imaging results would be compared over the course of the next seven months.
Scans were taken at three significant times: both groups underwent a baseline scan (both the control group and the intervention group prior to SMT). The intervention group then had another brain scan after the first SMT session and after the sixth SMT session. While the particular intervention was not chiropractic, it involved movements and manipulations that would be quite familiar to the chiropractic users.
While the paper includes all the statistical breakdowns, here are some important takeaways from the analysis :
- There was no significant difference between group one and group two when it came to fMRI results at the beginning of the study (i.e. before SMT).
- Statistical analysis was performed using standard tests, software and parameters and the difference was found to be statistically significant.
- Only two of the initial 16 participants dropped out of the study: one because of a metatarsal fracture and the other because his symptoms resolved under care.
The study used something called “real-time spot pressure” as the stimulus in the study. This essentially mimics the pain that participants with chronic low back pain feel when “sitting, walking or standing.” It followed another report in which “significantly different brain activity between patients with [chronic low back pain] and health controls during pressure stimulation in the low back area .”
The present study detected “greater brain activity in several brain regions including the right parahippocampal gyrus, left precuneus and posterior cingulate, in patients with [chronic low back pain] after SMT compared to healthy matched controls.” The authors remarked that “these brain regions are part of the default mode network (DMN), suggesting that activity in the DMN may be a neural correlate of [chronic low back pain] and DMN alterations may reflect responses to pain management with SMT in patients with [chronic low back pain].”
This same section of the brain has been seen to have alterations in patients with chronic low back pain before. Interestingly, this same section of the brain also has roles in regulating emotions and retrieving memories . The authors of the study suggested the possibility that “activity in the DMN is a neural correlate of [chronic low back pain” and the DMN may be involved in the analgesic effect of SMT and the brain responses to pain management in patients with chronic low back pain after SMT .”
As always, the study comes with limitations and thus opportunities for further research. Still, the possibility that spinal manipulative therapy may stimulate an area of the brain that regulates emotions, retrieves memories and potentially has an analgesic effect on chronic pain is an exciting possibility indeed.
- Ng, S. K., Urquhart, D. M., Fitzgerald, P. B., Cicuttini, F. M., Hussain, S. M., and Fitzgibbon, B. M. (2018). The relationship between structural and functional brain changes and altered emotion and cognition in chronic low back pain brain changes: a systematic review of MRI and fMRI studies. Clin. J. Pain 34, 237–261. doi: 10.1097/AJP.0000000000000534
- Tan, W., Wang, W., Yang, Y., Chen, Y., Kang, Y., Huang, Y., Gong, Z., Zhan, S., Ke, Z., Wang, J., Yuan, W., Huang, W., Zee, C., Chen, Z., and Chen, B., (2020), “Spinal Manipulative Therapy Alters Brain Activity in Patients With Chronic Low Back Pain: A Longitudinal Brain fMRI Study,” Frontiers in Integrative Neuroscience, DOI: 10.3389/fnint.2020.534595
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- Raichle, M. E. (2015). The brain’s default mode network. Annu. Rev. Neurosci. 38, 433–447. doi: 10.1146/annurev-neuro-071013-014030