So you can imagine that these people give birth without anaesthetic once or twice a day, for six, eight or ten weeks at a time, and then have a break. It's just awful. You suddenly realise that you have a pain behind your eye. I mean you're shattered, but at least you don't have the pain anymore. A cluster headache is a form of primary headache.
Secondary headaches are headaches that are reasonably easy to explain.
For example, if one has an infection or a tumour, or indeed someone simply kicks you in the head, then you have head pain due to the infection or blood, and it's called a secondary headache, secondary to that event. Primary headache is where the headache is the problem, and the common primary headaches are tension-type headache and migraine. Cluster headache is the third in the line, if you want, of the common primary headaches. Now how do cluster headaches distinguish themselves from migraine headaches, which I guess people are more familiar with. I was treated for migraines for the next 20 years.