What is the raw form of lsd given to patients for migranes?

It is NOT LSD: Ergot alkaloids are related to LSD, but are not the same chemical. They are now rarely used, since the triptans came into use over 30 years ago, and even less so since medications to prevent migraine (beta blockers, calcium channel blockers, anticonvulsants) came into use about the same time. Methylsergide and ergonovine are still available and helpful in some cases, and are cousins of LSD.