Just found this thread as a board newbie--I'm interested as 1) someone who used to get migraines, 2) a PADI instructor who may decline to accept a student for medical reasons, despite a medical OK, and 3) an MD who sees a fair number of migraine patients.
Various issues have been raised here: suitability to dive, medication use, CO2 retention, effects of O2, triggering factors, PFO, etc.
Regarding suitability to dive, it looks like all of us here feel it's OK, as we dive despite migraines, and would plan to abort if a migraine occured. An obvious issue is whether the migraine would risk one's safety, whether from a visual aura (I might have trouble reading my computer), distraction from severe pain, repeated vomiting, or other neurologic symptoms such as vertigo (a complaint I've often seen with migraine patients) or speech and motor symptoms (rare, but I had a patient whose 15 or 20 minute aura was not visual, but aphasia and right arm paralysis). I certainly would not have OK'd her to dive, but many migraine issues would be gray rather than black and white. A related issue is whether the condition could cause confusion regarding the diagnosis of DCS--which unfortunately could be the case with migraines.
As for medications, one question was whether it would be OK to use Imitrex after a dive. I doubt I or anyone could give an absolute answer, but I personally think it would be OK. Imitrex works by blocking receptors in cerebral veins that cause them to dilate in response to certain chemical messengers--the immediate cause of the headache, as far as we know. There is theoretic concern that other vessels could respond to the med by constricting, hence I'd pause before giving it to someone with, say, unstable angina. But I've ordered an injection in a 70 yo male (without known coronary disease) with no problems.
Obviously one should be sensible and cautious (i.e., don't dive) when using sedating drugs such as narcotics and antiemetics like Phenergan or Compazine. Preventive meds are another issues. Probably the most commonly used ones are beta blockers, also used for hypertension and coronary artery disease, and of some concern if used by divers. They can blunt the heart rate increase needed for maximum exercise.
As for CO2, those headaches are migraine-like, in that they result from increased cerebral blood flow (arterial) which would likely mean higher pressure/volume in the veins. Same mechanism as ice cream headaches. So it's understandable there could be confusion between the two.
As for O2, there have been reports of relief from vascular headaches with high flow O2 (at 1 ATM), but I think these were in cluster headaches (a cousin to migraines), so one could hypothesize that the higher O2 pressure at depth might be helpful.
As for triggers, by all means try to figure them out. I've had so few compared to many people that, except for one that followed a stressful episode (AFTER the stress was relieved), I couldn't identify anything. For some it's caffeine, (and for many, caffeine helps relieve them), certain foods, including some cheeses, red wines, etc. And be optimistic. Most people find they decrease in frequency as they get into middle age (I don't think I've had one since about age 48 or 49...knock on wood) or past menopause.
As for PFO, that's a tough one. That paper in Neurology gives one pause...but I don't plan to get a transesophageal echocardiogram to look for a PFO, as I don't think I'd stop diving and would continue to try to be conservative with my profiles.
Hope this post is of some use/interest....
