Of the estimated 30 million Americans actively afflicted by migraine, as many as 6 to 8 million— over 4% of the general population—suffer from what has come to be termed chronic migraine. As defined under the International Headache Society’s new diagnostic and classification system, chronic migraine implies that an individual with an established history of episodic migraine now is experiencing headaches at least 15 days per month, of which 8 days or more involve headache typical of migraine or headache that responds to symptomatic medication specifically intended for acute migraine treatment (ie, an ergotamine or triptan).
The flip side of this coin is that many of the headaches suffered by one who has chronic migraine may not resemble the headache of a “typical” migraine attack, often involving symptoms more suggestive of tension type headache. The eclectic mix of headache occurring in chronic migraine not infrequently may lead to misdiagnoses (eg, chronic tension type headache, “sinus headache”).
Each year, about 4% of the migraine population develops chronic migraine. What causes this “chroni- fication”? Large-scale epidemiologic studies have identified a number of factors associated with migraine chronification, and the factors most commonly cited in those studies have been chronic overuse of medication intended for acute headache treatment, obesity, anxiety/depression, hypothyroidism, and increasing frequency of headache. It should be stressed that in all cases these represent associations; in other words, these factors may contribute to chronification, result from chronification or possess no direct relationship to the chronification process itself (instead serving as markers for another, as yet unidentified process that itself is causal).
While the observation that migraine chronification is linked to a progressive increase in headache frequency may seem self evident, it is in line with rapidly accumulating scientific evidence that the brain “learns pain” and that early therapeutic intervention—before migraine attacks have reached a critical level of frequency—may serve to prevent the chronification process. Do not delay in seeking treatment! Recent studies have indicated that chronic migraine occurring daily for more than 6 months is particularly difficult to reverse.
Why does migraine become chronic? At present we can only speculate, but particularly intriguing is the strong association between chronification and a self-reported history of early sexual abuse. Can it be this or other severe emotional traumas occurring early in life may provoke an individual who is genetically inclined toward migraine to suffer a more prominent clinical expression of that inclination consequent to the emotional trauma, with the relative increase in migraine attack frequency serving as the trigger for eventual chronification?
Such speculation eventually may lead to research that benefits patients directly, but for now the management of chronic migraine involves a blend of patient education, identification and treatment of factors which may reinforce the chronification process, and judicious use of the same pharmacologic agents employed in treating episodic migraine. The following factors may be considered “reinforcers” of chronic migraine: overuse of symptomatic medication, coexisting mood disorder (anxiety, depression, or both), chronically disrupted sleep, hormonal instability, and uncontrolled attacks of acute, severe migraine. One of the most challenging aspects in attempting to treat chronic migraine is reconciliation of the first and last of these factors when both are present, ie, one simultaneously must cut back on the offending medication(s) being overused . . . and yet at the same time be aggressive in treating acute attacks, terminating them as quickly as possible.
What should you do, the migraineur who is developing—or has developed—chronic migraine? First, recognize the disorder for what it is, and do not underestimate its potential capacity for eroding your health, happiness, and productivity. If your headache frequency steadily has increased over the past few months, it’s time to seek assistance from a clinician experienced in the management of migraine. At the initial appointment come prepared to tell him or her precisely how many days of headache you have been experiencing per month and how that headache frequency compares with what previously was typical for you; how often during the month you are functionally incapacitated by headache and associated symptoms; what medications—including nonprescription agents —you currently are using to treat your headaches (along with the frequency of such use); whether you have an active mood disorder or chronically disrupted sleep; what, if any, event (eg, head/neck injury, beginning a new medication) may have coincided with the increase in your headache frequency; whether there has been any recent change in your hormonal status (eg, pregnancy, childbirth, initiation of hormone replacement therapy); and what medications you have tried for headache prevention in the past.
As with migraine generally, effective management of chronic migraine requires a therapeutic alliance between patient and clinician, with 2-way communication that is open and honest. If such management is undertaken early in the course of the chronification process, chances are excellent that you will experience a positive treatment result and remit back to a pattern of episodic, less frequent migraine.
John F. Rothrock, MD