New Findings Suggest Fibromyalgia Is Neuropathic, Not Depression Variant

Small nerve fibers in subjects with fibromyalgia syndrome are impaired, Nurcan Uceyler, M.D., of the University of Wurzburg in Germany and colleagues report in the June Brain. This is not the case for matched control subjects or for subjects with depression who do not have fibromyalgia syndrome. "This strengthens the notion that fibromyalgia syndrome is not a variant of depression, but rather represents an independent entity that may be associated with depressive symptoms," the researchers said. Furthermore, the findings point "towards a neuropathic nature of pain in fibromyalgia syndrome."

Still other research results point to a similar conclusion. For example, individuals with fibromyalgia are known to have an abnormally low pain threshold. They also have abnormally low levels in their spinal fluid of metabolites of two neurotransmitters—serotonin and norepinephrine—and abnormally high levels of substance P, an amplifier of pain messaging.

For more details about these findings, as well as information about treatments for fibromyalgia patients, see Psychiatric News. Information about fibromyalgia syndrome can also be found in American Psychiatric Publishing's Pain: What Psychiatrists Need to Know.

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Serious CNS Reactions Possible in Patients Taking MAOI Drugs, Says FDA

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On Tuesday, the Food and Drug Administration (FDA) released two drug-safety communications regarding serious CNS reactions that are possible when a patient is taking serotonin psychiatric medications. Both the antibacterial drug Zyvox (linezolid) and the drug methylene blue inhibit the action of monoamine oxidase A, an enzyme responsible for breaking down serotonin in the brain. Either drug may lead to serotonin build-up in the brain, causing the toxicity known as serotonin syndrome. Symptoms include mental changes (confusion, hyperactivity, memory problems), muscle twitching, excessive sweating, shivering, diarrhea, trouble with coordination, and/or fever.

Linezolid is used to treat pneumonia, infections of the skin, and infections caused by a resistant bacterium (Enterococcus faecium). Methylene blue is used to treat methemoglobinemia, vasoplegic syndrome, ifosfamide-induced encephalopathy, and cyanide poisoning. It is also used as a dye in diagnostic applications. The FDA recommends these two drugs not be given to patients taking serotonergic drugs, but recognizes there are some conditions that may be life-threatening or require urgent treatment with those drugs. 

Timely news about psychiatric drugs can be found regularly in the "Med Check" column of Psychiatric News. See the latest at http://pn.psychiatryonline.org/content/46/12/18.2.full.