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.