No - there is no absolute cause. I am sorry. I have been getting them for 17 some years now. Migraine is a progressive neurological disease. Early treatment generally means a better outcome in the long run.
some good sites:
I use all of those sites a lot.
Preventatives include anti-depressants, blood pressure medications, anti spasmodic, anti epilepsy drugs and others. There is a lot of thought that migraines are similar in origin to epilepsy.
Supplements work well for me. I am on 400 mg magnesium, 60 mg CoQ10, and 200 mg vitamin B2. What has worked though has changed over there years.
The best book on migraine is http://www.amazon.com/exec/obidos/ASIN/0060766859/...
well... if you contact me through the hubpages contact link on my site I would be happy to answer any migraine specific questions. I have done a lot of research and am happy to help once I know more about what you need to know.