The efficacy of
valproic acid in the treatment of intractable
chronic daily headache, unresponsive to traditional prophylactic medications, was examined prospectively in 16 patients. Dosage of the medication was adjusted to maintain serum
valproic acid levels between 50 and 100 micrograms/mL, provided there were no significant side effects at that level.
Valproic acid prophylaxis was of some benefit in only 2 of 16 patients. One of these two patients discontinued
therapy due to side effects. Eight of the 16 patients reported side effects which included
nausea,
diarrhea,
anorexia,
lethargy,
sleepiness,
confusion, blurred vision, and decreased libido. In conclusion,
valproic acid was not effective in controlling
chronic daily headache in the majority of patients in whom conventional
therapy had failed, and 50% of patients reported side effects. There is a significant disparity in the reported efficacy of this
drug in treating
chronic daily headache. This disparity is most likely due to the poorly-defined nature of this variety of
headache. It is, therefore, recommended that more stringent definition of this disorder be developed before therapeutic regimens are evaluated.