Myofascial pain syndrome patients — both those with and without fibromyalgia — showed no differences in pain vulnerability, according to a recent study. However, both groups displayed prolonged pain reaction after heat stimulation, compared to controls, and researchers attribute this possibly to a “disturbance of pain processing” in the brain.
Chronic myofascial temporomandibular disorders (myofascial TMD) is a group of disorders affecting the jaw joint, as well as the face and neck muscles related to it, causing pain, limited opening of the mouth, and joint noises.
No one knows what causes myofascial TMD , but a potential factor may be “central pain sensitization,” in which pain alters the way the central nervous system works. That causes the patient to experience more pain with less provocation.
However, only a subgroup of TMD patients show increased pain sensitivity in tests.
About 20 percent of people with myofascial TMD develop fibromyalgia — which is highly associated with central pain sensitization — as a second condition. Myofascial pain syndrome and fibromyalgia often show similar and overlapping symptoms like pain, headache, dizziness, and memory problems. As a result, people with both conditions are sometimes diagnosed and treated for only one of them.
That led the research team to hypothesize that the myofascial subgroup showing increased pain sensitivity may be those patients with a fibromyalgia comorbidity.
The team recruited 168 women and divided them into three groups according to their diagnosis – 100 myofascial-only patients, 25 myofascial patients with fibromyalgia, and 43 controls. All groups were compared in several tests measuring pain thresholds, increased painfulness after repeated heat stimuli (Temporal Summation; TS), and longer persistence of sensations after heat stimulation (After-Sensations; AS). This last test is an indicator of central pain sensitization.
Surprisingly, the study showed no differences in pain thresholds and TS among the three groups. However, all myofascial patients, with or without fibromyalgia, experienced a longer persistence of sensations after heat stimulation, compared to controls, indicating alterations of central pain mechanisms in both myofascial TMD and fibromyalgia.
Researchers also failed to confirm any differences in pain vulnerability in myofascial patients with or without fibromyalgia, as previously expected.
“Nevertheless, we would agree with the conclusion that myofascial TMD patients, with or without fibromyalgia, show evidence of disturbance of central pain processing,” the researchers concluded.