Dr. Pär Flodin and colleagues, from the Karolinska Institute in Stockholm, report their findings in the journal Brain Connectivity.
Fibromyalgia syndrome is a common and chronic condition of unknown cause that mostly strikes in middle age, although symptoms can often present earlier. Sufferers typically experience fatigue with long-term pain in several areas of the body, plus tenderness in soft tissues such as the muscles, joints and tendons.
Fibromyalgia (FM) is considered to be the prototypical central chronic pain syndrome and is associated with widespread pain that fluctuates spontaneously. Multiple studies have demonstrated altered brain activity in these patients. The objective of this study was to investigate the degree of connectivity between multiple brain networks in patients with FM, as well as how activity in these networks correlates with the level of spontaneous pain.
Somatosensory Hyperperfusion Linked to Severity of Fibromyalgia
The researchers confirmed the presence of perfusion abnormalities in patients with fibromyalgia.
They showed that bilateral hyperperfusion of the parietal cortex and of the pre- and postcentral cortices are strongly correlated with the Fibromyalgia Impact Questionnaire score. Hypoperfusion of the left anterior temporal cortex was also strongly correlated in patients with disease.
This is reportedly the first time investigators have observed a relationship between somatosensory hyperperfusion and the clinical severity of fibromyalgia.
“This reinforces the sensitization hypothesis,” the researchers emphasize.
Decreased brain connectivity in fibromyalgia patients
For their study, the Karolinska researchers compared brain activity in women with and without fibromyalgia. In fibromyalgia patients, they found decreased connectivity between brain areas that process pain and sensorimotor signals.
They suggest their findings show reduced brain connectivity may contribute to deficient pain regulation in people with fibromyalgia.
The results build on previous studies that have linked abnormal brain activity to poor pain inhibition.
For the study, 22 healthy women and 16 with fibromyalgia underwent functional magnetic resonance imaging (fMRI) brain scans while experiencing different levels of pain by having pressure applied to the thumb.
The day before the scans, the women completed tests to calibrate their pain sensitivity. A computer-controlled pressure stimulator applied pressure to their left thumb, while they rated the sensitivity. Pressure intensities derived from these ratings were then delivered in a random order as the women underwent the brain scans.
The participants had to refrain from taking pain medication and sedatives 48 hours before the assessment of pain and 72 hours before the fMRI scans. Altogether, each received 15 stimuli lasting 2.5 seconds each, at half-minute intervals.
Reduction in brain connectivity could impair pain perception
The results showed that the fibromyalgia participants had significantly increased pain sensitivity compared with the control group.
When they analyzed the brain scans, the team found differences in brain patterns between the healthy participants and those with fibromyalgia. The fibromyalgia participants showed “functional decoupling” between areas of the brain that process pain signals and other parts, including those that control sensorimotor activity.
The authors suggest this reduction in brain connectivity could impair pain perception.
The co-editor-in-chief of the journal, Dr. Christopher Pawela, an assistant professor at the Medical College of Wisconsin in the US, describes the study as “an important first step” in understanding how the brain affects widespread pain perception, which is a known characteristic of fibromyalgia.