Endometriosis and Migraine Risk

Endometriosis is a disease where the tissue that lines the uterus (endometrial tissue) is found outside of the uterus. The tissue attaches itself on other organs and can spread over a larger area over time. It acts just like the tissue inside the uterus during the monthly menstrual cycle. Endometrial implants, as this tissue is called, may be found anywhere in the body, but are mostly found in the pelvic region. Often, these implants are seen on the outside of the ovaries, the fallopian tubes, or the uterus.

The exact cause of endometriosis is unknown, but it occurs almost exclusively in menstruating women. It is rarely seen in women before puberty or after menopause, or in women who are not having monthly periods. One theory that explains how these cells get outside of the uterus is called the transport theory. The transport theory says that endometrial tissue moves to and attaches itself in the abdomen and other areas of the body by something called "retrograde menstruation." This means that the lining of the uterus that is shed at the end of the monthly cycle flows upwards instead of draining out of the body normally. The transport theory also says that the tissue may spread by going through the blood vessel circulation or the lymph nodes.

Recently researchers investigated the potential link between endometriosis and migraine headaches. This small study was conducted in Italy and involved 122 women diagnosed with endometriosis and 166 healthy control participants. Using the 1988 International Headache Society criteria, all participants were interviewed by a neurologist to determine headache disorders. The results found that the women with endometriosis had a higher risk of migraine headaches when compared to the control group. Also, migraine onset was noted in younger endometriosis patients. There was no difference in pain or frequency of migraines in the two groups. The authors stated that migraines were more frequent in those with endometriosis but severity was the same in the two groups.¹