A differential response to treatment with divalproex sodium in patients with intractable headache.

We consecutively recruited 75 patients with intractable headache syndromes, divided them into three groups (frequent migraine = FM, transformed migraine = TM, and tension type headache = TT) based on their headache symptoms and treated all 75 with divalproex sodium. Thirty-six patients (48%) reported a > or = 50% reduction in headache frequency. We noted significantly different treatment response rates in the three patient groups, with FM patients reporting the highest rate of improvement (11/18 = 61%), TM patients an intermediate rate (22/43 = 51%), and TT patients the lowest response rate (3/14 = 21%). These data suggest that prophylactic therapy with divalproex may be effective in selected patients with intractable headache syndromes and that identification of clinically distinct headache subtypes may assist in predicting response to treatment.