Headache induced by chronic substance use: analysis of medication overused and minimum dose required to induce headache.

Background: The International Headache Society has defined the diagnostic criteria for headache induced by substance use. Recently, a revision to these criteria has been proposed.

Objective: To consider whether the International Headache Society criteria for headache induced by substance use and the proposed revisions for the classification of daily and near-daily headache with medication abuse permit classification of patients commonly seen in a headache center.

Methods: One hundred fourteen consecutive patients (96 women [84.2%] and 18 men [15.8%]; mean age, 54.2 years [SD, 14]) with headache and chronic overuse of medications, admitted for detoxification to the inpatient unit of a headache center, participated in the study. The initial headache, medications and doses used, duration of daily medication use, and means of medication administration were studied.

Results: Eighty-one patients (71%) had an initial headache of migraine without aura, 13 patients (11.4%) had migraine without aura and coexistent tension-type headache, 11 (9.7%) patients had migraine with and without aura, and 9 patients (7.9%) had episodic tension-type headache. Medications overused by patients included analgesics combined with barbiturates or other nonnarcotic substances in 39.5%, simple analgesics in 38.6%, triptans in 11.4%, and ergotamine in 10.5%. Using the International Headache Society diagnostic criteria, we were able to classify only 28.1% of our patients; the proposed revised criteria for daily and near-daily headaches with medication abuse permitted the classification of 46.4% of patients.

Conclusion: The minimum dose of medication required to induce chronic headache should be revised because a high proportion of patients are not classifiable using either the International Headache Society diagnostic criteria or the revised criteria recently proposed. A more comprehensive definition for the required minimum dose might be used. Triptan abuse can cause chronic headache and should be included in the International Headache Society classification.