Low back pain is the leading cause of physical disability worldwide, according to WebMD, and current interventions provide almost no relief to this epidemic that affects about 10 percent of global population. Even though pinched nerves, tight back muscles, or a weak hip are often blamed for low back pain, current evidence shows that the brain may ultimately be the blame.
Physiotherapist Mark Gibson from Perth, Western Australia, recently reviewed several research papers on “red flags” of low back pain, including an Australian study from the University of Sydney that investigated ” the use of recommended signs in the identification.” These signs include cancer/malignancy, infection, spinal fractures, inflammation, and cauda equina compression. However, Gibson mentioned that clinicians need to be “mindful that there are many reported case studies demonstrating red flag disorders that do not show any red flag signs.” Low back pain may seem mechanical in nature but current physiotherapy care is not improving the patients’ outcomes much. Perhaps neuroscience could help reveal some answers or clues.
First, current research show a poor or lack of strong correlation between structure and back pain. For example, a Turkish study that was published in Pain Physician in 2008 showed that the angle of the lumbar spine and sacrum’s position do not differentiate between those with chronic or acute low back pain. A large Iranian study that involved 600 middle-aged men and women from the University of Social Welfare and Rehabilitation Sciences in Tehran showed that biomechanics, such pelvic tilt, leg-length discrepancy, and muscle length are not factors that contribute to low back pain. Finally, a systematic review that was published in The Spine Journal on January 2010 examined eight high-quality studies on awkward occupational posture and low back pain. Six of these studies showed “no association between awkward postures and [low back pain].”
Since the biomechanical model does not explain or treat low back pain well, it is more plausible that the brain and the nervous system are to blame. However, the neuroscience explanation of pain is not new. A 2004 pilot study published in The Journal of Neuroscience showed that 26 patients with chronic back pain had five to eleven percent less neocortical gray matter volume in the brain than those in the matching control group. This loss is equivalent to the volume lost in 10 to 20 years of normal aging. The loss of some gray matter volume may alter and worsen pain perception. The researchers noted that the different lifestyle factors among the patients cannot be ruled out as factors to contributing to brain matter loss, which may explain the large differences in percentage.
In 2011, a team of researchers from the U.K., Australia, and Switzerland published a review paper in Manual Therapy that examined numerous studies since the 1990s that showed how the brain structure and function change and are different among those with low back pain. These changes include reduced gray matter in the thalamus, prefrontal cortex, somatosensory cortex, and the brain stem, sensitivity to “noxious stimulations” and muscle pain, and neurochemistry. Despite the evidence, the researchers acknowledged that this field of research is still in its infancy and much has yet to be learned about pain in relation to low back pain. “We are continuing to learn more about the cortical changes apparent in [chronic low back pain] and the clinical implications of these changes.”
Even if the brain is mainly to blame on low back pain, the back itself should not be entirely ignored. Physiotherapist Tony Ingram from Halifax, Canada wrote in Medbridge that while current evidence show a poor correlation between imaging results and back pain, it may be possible that “current imaging technology simply is not capable of detecting what’s important.” Current imaging techniques, such as MRI, look at macroscopic details, not microscopic. Ingram stated that no current research has done on imaging techniques with a patient’s body positions, such as prone, supine, or on the side. “You can’t also MRI someone while they walk or do stairs,” he wrote. It is never really a all-or-nothing scenario when treating or identifying the cause of back pain.
By Nick Ng