Cluster headache. Recent developments in clinical characterization and pathogenesis.

The preliminary results of some new studies on cluster headache (CH) point to: (a) the existence of a form, secondary episodic CH, which should be included in the classification of headache; (b) the significant role played by air temperature variations and the number of daylight hours on the onset of CH active periods. Data from the evaluation of pupil response to corneal stimuli suggest a widespread alteration of the pain/autonomic integrative processes at the level of the central nervous system. Finally, data on new preventive (i.e., verapamil and ozone) and symptomatic (i.e., hyperbaric oxygen and sumatriptan) treatments are reported.