New reviews discuss the neurobiology of fibromyalgia, assessing the best treatment options, both pharmaceutical and behavioral.
Clauw DJ. Fibromyalgia: A Clinical Review. JAMA (2014) 311:1547-1555. doi:10.1001/jama.2014.3266.
Engel CC. Review: In neuropathy, fibromyalgia, or chronic pain, duloxetine reduces pain but increases adverse events. Ann Intern Med (2014) 160:JC12. doi:10.7326/0003-4819-160-8-201404150-02012
Two new reviews this week offer information and guidance about the always difficult problem of fibromyalgia.
In JAMA, University of Michigan's Daniel Clauw gives an overview of the neurobiology and some expert perspectives on treatment..
Fibromyalgia is a centralized pain state, in which peripheral nociceptive input is responsible for some of a patient’s pain, but central nervous system factors amplify the nociceptive pain, or fail to dampen the nociceptive pain. An individual’s “set point” for pain is set by the levels of neurotransmitters in the pain pathways that may also control sleep, mood, and alertness.
Functional, chemical, and structural brain neuroimaging studies have shown a biological basis for these pain amplification syndromes. Functional magnetic resonance imaging studies show brain activation patterns in pain processing areas when fibromyalgia patients experience a mild pressure or heat stimulus. As a consequence – and as evidence – of this concept, drugs used to treat peripheral pain, such as nonsteroidal anti-inflammatory drugs, opioids, and corticosteroids, are ineffective. In contrast, low-dose naltrexone may be effective.
Other pharmacological and behavioral treatments are effective. Clauw largely follows (and updates) the recommendations of the Canadian National Fibromyalgia Guideline Advisory Panel, and he summarizes the level A evidence in a large table. Education, cognitive behavioral therapy, and exercise all have strong (level A) evidence for long-term (>1 year) improvement that often exceeds the effects of pharmaceuticals.
Clauw reviews the most effective pharmaceutical options, and is more sympathetic than the Canadian guidelines to complementary and alternative therapies as adjuncts (although the evidence is weak), because giving patients a sense of control and choice may stimulate the placebo response. The synthetic cannabinoid nabilone is supported by level A evidence, he notes.
Few patients fake their symptoms to benefit financially, Clauw writes, but when patients enter the disability and litigation systems, they almost always worsen clinically. (“If you have to prove that you’re sick, you can’t get well.”)
In the ACP Journal Club, Engel discusses the January 2014 Cochrane review of duloxetine for fibromyalgia, neuropathy, or chronic pain.
There were 18 randomized controlled trials (RCTs), 16 with placebo.
Duloxetine reduced pain for all conditions, but increased adverse events. For fibromyalgia, in studies of 27 to 28 weeks, the number needed to treat was 12.
Future RCTs should compare duloxetine to tricyclic antidepressants, pregabalin and gabapentin, says the review, and should have follow-up longer than 28 weeks.