The comorbidity of endometriosis and migraine was first discovered in 1975, but until now has not been fully acknowledged. Although both diseases share some epidemiological and clinical features, the nature of their relationship remains unclear. Does endometriosis cause headaches? Or is it migraine that makes endometriosis more detectable? Why do they have so much in common? These issues are discussed in the population-based study performed by Taiwanian scientists, which proves that indeed „women with endometriosis are more likely to suffer from migraines” (1).
Endometriosis affects about 3-10% of women in reproductive age and up to 50% of those who deal with infertility (2). Around 26% of women and 8% of men suffer from migraine headaches (3). What is interesting, about half of all women with migraine report an association with menstruation, but only 8% experience headaches exclusively during menstruation (4). Sex hormones strongly influence both migraine and endometriosis, so no wonder that there is a connection. According to the discussed study (1), females suffering from endometriosis are two times more prone to developing migraine, which occurs usually after the diagnosis of endometriosis.
Migraine and endometriosis are more prevalent in females with early menarche. Headaches are common in fertile women and often start around the age of menarche, improving after menopause. According to the Sampson’s theory concerning the pathogenesis of endometriosis, lesions form as a result of retrograde blood flow through the salpinx. So in this case menstruation may be considered as a trigger for both endometriosis and migraine. These sisterly conditions rely on estrogen level. Menstrual migraine attacks seem to be precipitated by the rapid fall of estrogen at the end of luteal phase of menstrual cycle. Estrogens are endometriosis’ enemy because they stimulate the development of endometrium, ectopic as well.
Therefore it may seem predictable that during gonadotropin releasing hormone analogues (GnRH-a) therapy for endometriosis, migraine attacks abate, because there is no rapid fall of estrogens. On the other hand, headache is in fact listed as a common side-effect of GnRH-a (5). Other drugs used in the treatment of endometriosis, particularly danazol and oral contraceptives, are also associated with headache (6). The mechanism of these effects is unclear, but here it seems that the comorbidity of endometriosis and migraine may be explained by the use of hormone therapy. However, Taiwanian scientists disprove this theory.
Apart from the hormone dependence, both diseases are known for the debilitating pain they cause. Migraine is generally characterized by unilateral, pulsating headache, which lasts from 4 to 72 hours and can be accompanied by photophobia, phonophobia and nausea. Very often the symptoms do not easily react to medication. Most patients diagnosed with endometriosis suffer from dysmenorrhea, some from dyspareunia, painful urination or defecation. Endometriosis lesions are found in about 33-50% women with chronic pelvic pain. These observations lead to notion that pain is evident in both ailments for a reason.
Scientist speculate that endometriotic implants develop both sensory and autonomic nerve supply, mediating nerve impulses to the central nervous system causing central sensitization. This results in the decrease of the threshold for pain and an increased reaction to impulses from healthy organs, such as brain (7). This was suggested when it turned out that migraine was reported by women with endometriosis not more often than by women with pelvic pain caused by other diseases (8).
However, migraneurs’ pain threshold is lowered anyway (9) and probably regardless of endometriosis. So it is suggested that the early symptoms of the gynecologic disorder might be spotted earlier by women with migraine, increasing the likelihood that it will be properly and quickly diagnosed.
Even if all of the conceptions listed above might be speculative – genetics never lie. The Australian study based on a cohort of 931 families with at least 2 sisters with endometriosis indicates that common genetic influences underlying migraine and endometriosis fully explain their co-morbidity (10). The scientists included personality trait neuroticism in the study and it did not make an impact on the results. However, it has been observed (11) that endometriosis is associated with high prevalence of conditions comorbid to migraine such as depression, anxiety, irritable bowel syndrome, fibromyalgia, chronic fatigue syndrome and interstitial cystitis. Frequency of chronic headache was higher for migraneurs with endometriosis compared to those without the disease.
Although both endometriosis and migraine are common diseases and moreover comorbid, their pathogenesis is unknown. However, scientist pursue the search for answers and this time they agree- endometriosis is comorbid with migraine.
1.Meng-Han Yang, Peng-Hui Wang, Shuu-Jiun Wang et al. Women with Endometriosis Are More Likely to Suffer from Migraines: A Population-Based Study. PLoS One. 2012; 7(3): e33941.PMCID: PMC3307779.
2.Katz VL. Endometriosis. In: Katz VL, editor. Comprehensive gynecology. 5. Philadelphia: Mosby Elsevier; 2007.
3.Wang SJ, Fuh JL, Young YH et al. Prevalence of migraine in Taipei, Taiwan: a population-based survey. Cephalalgia. 2000;20:566–572
4.Couturier EG, Bomhof MA, Neven AK et al.. Menstrual migraine in a representative Dutch population sample: prevalence, disability and treatment. Cephalalgia. 2003;23(4):302–308. doi: 10.1046/j.1468-2982.2003.00516.x. [PubMed] [Cross Ref]
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6.Stovner LJ, Aegidius K, Linde M. Endometriosis and headache. Curr Pain Headache Rep. 2011 Oct;15(5):415-9.
7.Berkley KJ, Rapkin AJ, Papka RE. The pains of endometriosis. Science (New York, NY) 2005;308(5728):1587–1589. doi: 10.1126/science.1111445.
8.Karp BI, Sinaii N, Nieman LK, Silberstein SD, Stratton P. Migraine in women with chronic pelvic pain with and without endometriosis. Fertil Steril. 2010.
9.Moulton EA, Burstein R, Tully S et al. Interictal dysfunction of a brainstem descending modulatory center in migraine patients. PLoS ONE. 2008;3(11):e3799. doi: 10.1371/journal.pone.0003799.
10.Nyholt DR, Gillespie NG, Merikangas KR et al. Common genetic influences underlie comorbidity of migraine and endometriosis.Genet Epidemiol. 2009 Feb;33(2):105-13.
11.Tietjen GE, Bushnell CD, Herial NA et al. Endometriosis is associated with prevalence of comorbid conditions in migraine. Headache. 2007 Jul-Aug;47(7):1069-78.
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