Relationship of migraine and other forms of chronic pain.

The disability of migraine, a highly prevalent condition, is worsened by a second comorbid chronic pain condition. There is evidence of a relationship between migraine and several visceral pain conditions including irritable bowel syndrome, endometriosis, and dysmenorrhoea, as well as nonvisceral conditions including temporomandibular dysfunction, fibromyalgia, and lower back pain. While the mechanisms linking these conditions are inadequately surmised, a two-way relationship between migraine and these comorbidities likely exists. The progression and chronification of migraine is associated with peripheral and central sensitization, which may predispose to other conditions. Conversely, aspects of the mechanism of each comorbid condition may promote further migraine attacks. This chapter introduces each comorbidity, briefly summarizes the existing evidence, and discusses implications for treatment.