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

VOA: special.2010.03.30

The sheer cacophony of the clustered consonants in this line sets off -or has the potential to set off -- a powerful cluster of feelings.

这句诗中辅音全然不和谐，使人觉得,或者有意向让人觉得-，有力量的层叠之感。

耶鲁公开课 - 弥尔顿课程节选

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