Chronic migraine and medication overuse: still a debate.

Progressive headache consequent to drug overuse is an old critical issue. 1 Migraine specially and the development of its daily or near-daily presentation due to overuse of immediate-relief medications is suggested since the eighties when Mathew and col. described this transformation and named it transformed migraine. 2 These authors called the attention for the fact that migraine may progressively transform into daily headache and lose its typical clinical features under the influence of analgesic overuse. Almost simultaneously, Kudrow 3 demonstrated an improvement in attack frequency in those patients able to withdraw from this pattern of drug consumption. Even before that, ergotamine tartrate was associated with dependence and withdrawal headaches introducing the term rebound and postulating that all ergots could promote increasing of headache frequency. 4 Other researchers and clinicians have been demonstrating that migraineurs may develop daily or near-daily headache when using excessively caffeine, opioids, triptans and analgesics, even for purposes other than headache, and that improvement in the frequency of headache attacks occurs following abrupt discontinuation with the patients restoring the initial episodic presentation of their head pain. Despite chronic daily headache and chronic or transformed migraine patients do overuse symptomatic medications in a frequent manner, the debate concerning whether this pattern of overuse is responsible for the frequency evolution or migraine itself is a progressive and relapsing neurologic disorder, that will turn into daily or near-daily headache as part of a natural history disease evolution, remains unresolved and a matter of disputing. Concepts in favor of a consequence rather than a cause recall the absence of true placebo-controlled trials proving the existence of headache due to drug rebound (with the honorable exception of Silverman's trial on caffeine) 10. In addition, there is still doubt whether rebound headache occurs from repeated episodes of withdrawal (mini-withdrawals) or the process of transformation involves a pro-nociceptive effect of symptomatic medications overuse in this population of patients. 11 Moreover, population-based studies have been showing that only one third of chronic or transformed migraineurs overuse medications for acute treatment despite of the observations in specific clinic-based studies demonstrating that over 80% of chronic migraine patients do take analgesics on a daily or near-daily basis. Another point of interest in this debate is the fact that long-term prognosis for those that were able to withdraw did not reveal a significant improvement in order to support the suggestion emphasizing the medication overuse as the sole cause …