The Cleveland Clinic says the cause of cluster headaches is in a brain area known as a trigeminal-autonomic reflex pathway.

VOA: special.2010.03.30

The Cleveland Clinic in Ohio says the cluster headache can be many times more intense than a migraine.

VOA: special.2010.03.30

Cluster headaches occur in cycles: sufferers can experience several headaches a day for weeks or even months on end.

VOA: standard.2009.12.17

"Our study showed for the first time a clear difference between oxygen and air in the treatment of acute cluster headache.

VOA: standard.2009.12.17

Dr.Peter Goadsby of the University of California and other researchers followed The doctors treated for cluster headaches in each patient using air and oxygen in separate trials.

VOA: standard.2009.12.17