BAM is a variant on the theme of migraine. It is a rare form of migraine, accounting for somewhere between 1 in 400 and 1 in 500 of all clinically diagnosed migraine cases.

When classifying headaches according to presumed site of origin, BAM belongs in the category of "episodic headaches of uncertain mechanism." This grouping includes (1) migraine, (2) cluster headache, and (3) acute cerebral vascular insufficiency.