Endometriosis - caused when tissue that normally lines the uterus grows at other sites - may produce more than pelvic pain. It seems to increase the risk of migraine, Italian researchers report.

Previous reports have linked endometriosis with a variety of disabling conditions, such as autoimmune diseases, chronic fatigue syndrome, and fibromyalgia.

Dr. Simone Ferrero and colleagues, from the University of Genoa, assessed the presence and characteristics of headache disorders among 133 women with endometriosis and a comparison “control” group of 166 women without endometriosis.

Subjects in both groups were interviewed by an experienced neurologist who classified headaches based on a standard international system.

Over 38 percent of participants with endometriosis had migraines, more than double the 15 percent rate seen in controls. In particular, migraine with aura affected 18 women with endometriosis compared with just two control subjects, the researchers note in the journal Human Reproduction.

The team also found that the age when migraines began occurred about 5 years earlier in endometriosis patients than in controls.

“I believe all gynecologists should always ask their patients with known or suspected endometriosis, ‘do you suffer from headaches?’” Ferrero said in a statement. “If they do, then consultation with a neurologist should be advised.”

SOURCE: Human Reproduction, October 28, 2004.