TUESDAY, May 9 (HealthDay News) -- In patients with fibromyalgia, the menstrual cycle may affect pain processing, with greater activation in the luteal and ovulation phases, according to research presented this week at the annual meeting of the American Pain Society in San Antonio, Texas.
Serge Marchand, Ph.D., of the Faculty of Medicine at Universite de Sherbrooke in Quebec, Canada, and colleagues measured diffuse noxious inhibitory control (DNIC) in 45 patients with fibromyalgia and 20 healthy controls by applying heat to one arm for two minutes and then subjecting the contralateral arm to cold immersion. The researchers also measured the blood level of sex hormones including testosterone, estrogens and progesterone.
Control patients reported significantly less pain after cold immersion than fibromyalgia patients, who had similar pain ratings before and after the procedure. There was no difference between the two groups in levels of sex hormones. Fibromyalgia patients, however, had greater DNIC activation in the luteal and ovulation phases of the menstrual cycle than at other times.
"We found no significant correlations between sex hormone levels, pain perception and DNIC, which probably reflects the complexity of the mechanisms implicated in the pathophysiology of fibromyalgia," the authors conclude. However, the "results suggest that endogenous pain control mechanisms are deficient among fibromyalgic patients and modulated by menstrual cycle. These results clearly suggest a deficit in the activation of DNIC in fibromyalgia patients."
Abstract
