Chronic low back pain may alter pain control mechanisms in the brain, according to a functional MRI study. A change observed even more significantly in people who are on sick leave and who stay at home.
Most of the time, acute back pain goes away with proper treatment and a little time. Unfortunately, in 15% of cases, lower back pain is permanent.
Low back pain is the most common back pain. It is characterized by pain in the lower back, at the level of the lumbar vertebrae. This pain can come after a specific effort or a sudden movement. It is often linked to the wear and tear of the intervertebral discs and the joints and tissues that surround it. 84% of French people have or will have low back pain during their lifetime, according to Health Insurance.
Sick leave, an aggravating factor
Researchers from theAmerican College of Rheumatology, in Chicago, observed a weaker functional MRI signal in areas of the brain related to emotions in patients with chronic back pain on sick leave. These patients tended to be less distracted from pain during tests of attention, showing a reduced MRI signal in brain areas related to emotions.
“We hypothesize that these areas of the brain might already be chronically activated in people on sick leave,” said Ari Halpern, one of the study’s authors. “They might constantly be confronted with an increased perception of pain,” he added.
Source of pain difficult to locate
The great difficulty in treating chronic back pain has led researchers to wonder if there are specific characteristics of brain physiology in these people. “Often these patients don’t respond well to anesthetics, physiotherapy, or conventional painkillers intended to treat musculoskeletal pain,” Ari Halpern explained.
For their study, the researchers divided 74 participants into three groups: patients with chronic lower back pain on sick leave; patients with chronic low back pain who are not on sick leave; and control individuals without chronic low back pain.
The researchers induced sharp pain through the pressure of their thumb. They then used a functional MRI that visualizes changes in cerebral blood flow when neurons in the brain are activated. Finally, they examined the study participants’ brains before and after acute pain stimulation.
Different blood flow in sensory regions
“We found an alteration in the neuroplasticity of patients suffering from chronic low back pain in areas of the brain other than the sensory regions”, develops Ari Halpern. Activation of blood flow in sensory regions of the brain was lower in the sick leave group than in the control group. In patients with back pain who were not on sick leave, there was also an impairment but this was not as significant as that of the sick leave group.
Pain control mechanisms in the brain of chronic pain patients may therefore be impaired. “We believe that the modulation of acute pain participates in the mechanism of propagation of chronic pain perception,” said Ari Halpern.
However, the study does not indicate whether the change in neuroplasticity occurred before or after the patient went on sick leave. “But many published studies tell us that the longer the sick leave, the less likely patients are to return to work and the less likely they are to recover from back pain,” he adds.
In conclusion, the right treatment for back pain is to move, as advised by health insurance
.
