New Insight into Menstrual Migraines
by Sophia Cariati

(Washington DC, 5/16/02): According to results of recent research that sheds new light on the cause of menstrual migraines, fluctuations in estrogen levels may turn genes that control pain and blood vessels on and off. These findings may help experts develop more effective treatments for the estimated 6 million American women who have "menstrual migraine." Menstrual migraines are more frequent and intense migraines that happen around the time of menstruation or ovulation.

Migraines are headaches characterized by throbbing pain on one side of the head, nausea, and hypersensitivity to light and noise. They are three times more common among women than men. But this gender gap is only present in adults; before adolescence, girls and boys experience migraines at similar rates. Combined with the fact that migraines vary with pregnancy, birth control pills, menses, and menopause, this lack of a gender gap before adolescence has pointed the finger at fluctuating female sex hormones.

While the exact cause of migraines remains a mystery, most experts agree that changes in blood flow in and around the brain play an integral role. According to a leading theory, stress, alcohol, hormones or other triggers cause electrical changes in the brain that lead to the opening and inflammation of surrounding blood vessels. Serotonin, a naturally occurring chemical in the brain, seems to be involved in this inflammatory process. The pain and other symptoms of a migraine are thought to arise from alterations in blood flow and inflammation.

Menstrual migraines are often more severe and last longer than other headaches, and they are more difficult to treat. "Cyclical drops in estrogen are thought to trigger menstrual migraines," said Loretta Mueller, DO, a headache specialist at the University of Medicine and Dentistry of New Jersey in Moorestown. "Exactly how is still not known."

New Insight into Menstrual Migraines
About 20 percent of migraine sufferers experience a physical warning sign called an aura before a headache sets in. Auras are visual changes such as seeing spots or blurred vision. Increasing evidence suggests that an electrical chain reaction in the brain, called cortical spreading depression, is the cause of migraine aura.

K. Michael Welch, MD, and colleagues at Kansas University Medical Center in Kansas City, examined how estrogen affects the genes of mice experiencing artificial cortical spreading depression. The researchers caused electrical changes in the brains of mice to mimic the process of migraine. Dr. Welch presented the study results at the recent annual meeting of the American Academy of Neurology.

Three groups of mice were studied: males, females with no ovaries, and females with no ovaries who were receiving estrogen replacement. The electrical changes in the brain turned on similar genes in all three groups of mice. However, female mice treated with estrogen produced a greater amount of brain chemicals known to reduce the inflammation and dilation of blood vessels that cause migraine pain. Thus, estrogen functioned as a built-in pain reliever and protection from cortical spreading depression.

A drop in estrogen precedes the onset of the menstrual period. Dr. Welch theorizes that this fall in estrogen may trigger migraine by favoring the dilation and swelling of blood vessels surrounding the brain. According to Dr. Welch, the research may someday help experts identify the genes that might be good candidates for new migraine treatments.

Are Menstrual Migraines Different?
Clinicians generally treat menstrual migraines the same as any other migraine. Over-the-counter pain relievers and anti-inflammatory medicines help some women. For others, prescription drugs such as triptans are a better choice. Along with medication, doctors help patients target and avoid headache triggers and reduce stress. Hormone treatment is often ineffective and is usually a last resort, according to Dr. Mueller.

Some experts wonder if the pain of menstrual migraines might be relieved more effectively with a different approach. "Seventy-five percent of migraine sufferers are women and more than half report hormonal triggers," said Dr. Mueller, "But we still don't know if we should be treating these headaches any differently than migraines in men." Only larger, well-designed clinical trials will be able to answer this question.

The Society for Women's Health Research is the nation's only not-for-profit organization whose sole mission is to improve the health of women through research. Founded in 1990, the Society brought to national attention the need for the appropriate inclusion of women in major medical research studies and the resulting need for more information about conditions affecting women. The Society advocates increased funding for research on women's health, encourages the study of sex differences that may affect the prevention, diagnosis and treatment of disease, and promotes the inclusion of women in medical research studies. Dr. Donnica Moore has been a member of the Society since 1990 and is a past member of its Board of Directors.

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Created: 5/16/2002  -  Sophia Cariati