Chronic migraine associated with the Chiari type 1 malformation.

OBJECTIVE: Our objective was to assess the frequency and clinical characteristics of migraine in the patients with CM-1. METHODS: We analyzed migraine in 73 patients with CM-1. Migraine was classified according to the new International Headache Society criteria. We did not include patients who had intracranial, parenchymal, or cervical lesions other than CM-1 on brain and cervical magnetic resonance imaging. RESULTS: Of the 73 patients diagnosed as having CM-1, 11 (15.06%) had migraines; of them, 8 (10.95%) had chronic migraines, 2 (2.73%) had migraines with auras, and 1 (1.36%) had migraines without auras. The patients who had both migraines and CM-1 (group 1) were compared regarding clinical characteristics and demographic features to the control group having chronic migraines. The control group comprised subjects free of CM-1. Onset age of pain was earlier and the frequency of headache days per month, baseline pain intensity, exacerbation of pain intensity, nausea, vomiting, and pain aggravated by physical activity were significantly higher in group 1. CONCLUSIONS: Although we found the frequency of migraine to be similar to that in population-based studies, we detected a threefold increased frequency of chronic migraine in this special population. We believe that CM-1 may be a factor associated with chronic migraine.