Almost every thirtieth person in Germany suffers from the chronic pain of this disease. And yet it is dismissed by many doctors as a psychosomatic condition, or in the worst case is not even taken seriously. In fact, until recently neither the cause nor treatment of fibromyalgia syndrome were understood (FMS). Many patients changed doctor several times before getting the correct diagnosis and adequate treatment. Yet for more than 10 percent of these patients physicians very often prescribe ineffective opiates – contrary to the recommendations given by the current guidelines.
Impaired processing of stimuli in the CNS
Are fatigue and depression part of the disease or are they just a result of its persistent hypersensitivity present in various regions of the body? It seems as if great mental and physical strain are important triggers of the disease. Nevertheless, there is little hard data on and few insights into the genesis and course of its physiological progression. This has changed in the last few years at least in some important respects, because publications from Würzburg and Boston shed a few rays of light on what goes on in the body of fibromyalgia patients.
In November Marco Loggia from the Harvard Medical School published the results of his neurological research on the FMS brain. According to these results the strong sensations of pain could arise from a fault in the reward centre region. By using a pressure cuff the researchers delivered a short stimulus to the subjects. While the control group indeed showed a strong response in the area tegmentalis ventralis to the manifestation of stimulus and irritation, for 31 patients there were significantly weaker nerve impulses present. The researchers led by Loggia conclude that pain processing in the CNS had changed. “These findings may explain the increased sensitivity to pain, but also the lack of effect of analgesics such as opioids, as is observed with these patients”, suspects Marco Loggia.
Small Fibre Neuropathy
While the American research group recorded defects in the stimulus processing process, Nurcan Üçeyler and his colleagues at Würzburg Neurology seem to have discovered the typical symptoms involved in triggering abnormal pain sensations. Using quantitative sensory tests they determined thresholds for temperature and pain sensation for 25 FMS patients and compared them to those of depressive control subjects without pain syndrome. Just as with the determination of pain-associated evoked potentials, fibromyalgia patients reacted significantly more weakly. The cause of the restricted conduction was found by the researchers via punch biopsies of the skin: the number of small nerve fibres was lower than it was among patients with depression who had no fibromyalgia or than it was for healthy subjects.
Fibromyalgia thus seems to belong to the “small fibre neuropathies”, where only damaged A-delta fibres and C-fibres occur. The myelin sheath of nerves is very thin or totally absent. With the Würzburg patients as well the pathways with thicker sheaths are obviously not affected. A confirmation of the Würzburg results, which the journal “Brain” published in Spring, also appeared some months later in the journal “Pain”. Anne Louise Oaklander from Harvard also found among FMS patients a greatly reduced number of small nerves in the skin. Whether such a polyneuropathy causes the disease or is merely a symptom of another process for the time being remains something unclear.
Why do patients with fewer nerve fibres have greater pain? Until now there has only been speculation: this could be due to overactivity of the damaged but not yet dead fibres, or to a selective choice of forwarding signals. Pleasant contact signals no longer reach the central nervous system, whereas painful stimuli remain as “left overs”.
More and more findings also suggest that there is an inflammatory process involved in the disease. Thus with the complete genome sequencing of patients some genetic variations were found which are closely associated with inflammatory cytokines. Elevated levels of inflammatory cytokine IL-17A were found by Brazilian researchers among their patients.
New guidelines dispense with “tender points”
Ten professional societies in recent years developed a new FMS guideline and published it in Summer 2012. In contrast to earlier times, the “tender points” of the body, used to characterise the condition more precisely, are no longer counted. Instead, an extensive questionnaire now seeks to more exactly describe the patients’ condition. It looks for pain regions, but also accompanying symptoms such as sleep quality or cognitive impairments.
The authors of the new treatment indications have tested a total of 52 different forms of treatment described for fibromyalgia patients. Only five of them were categorised under the label “strong recommendation”. With mild forms, specialists in pain medicine and rheumatology advise physical and psychosocial activity against depression, which often accompanies the disease. For more severe forms multimodal therapy is employed which includes drug treatment and appropriate behaviour management. The authors of two Cochrane reviews emphasise at least some use of cognitive behavioural therapy, as well as acupuncture.
Mistaken treatment choice due to billing incentives?
If one believes one survey, about half of the doctors still give their patients anti-inflammatory drugs such as ibuprofen, diclofenac or naproxen. Psychotropic drugs are still widespread. Both in the hospital as well as in outpatient departments most medical professionals still treat their patients following measures other than those in the current guidelines. These instructions for doctors and patients describe fibromyalgia syndrome as a functional somatic syndrome rather than a mental disorder.
Pain physician Dr. Ursula Marschall, Head of Barmer GEK’s Competence Centre for Health, provides a reason for the uncertainty: “Misuse of invasive measures is being triggered by billing incentives. In addition, the patient’s desire for relief of symptoms and medically futile attempts to locally treat chronic pain in multiple body regions enter the picture.”
The new scientific evidence should be the first step in extricating fibromyalgia syndrome from the field of purely psychologically induced pain and no longer focusing on immobilising the patient. As part of the next guidelines the task at hand could be to tackle the disease at its cause.