Relative frequency of headache types: a longitudinal study in the tertiary care.

Unlabelled: In order to properly assess patients with primary headache, one needs to follow the cases up longitudinally. In Brazil, there were no studies using this methodology published after the publication of the latest issue of the International Classification of Headaches in 2004 - ICHD-2. This is especially important when we consider that it was only after such publication that we had the criteria used to classify some types of headaches which evolve with daily, or almost daily, spells, and which are very common in tertiary health care centers.