As far as diving with migraine is concerned–there is mixed opinion as to the proper thing to do. Some think it to be an absolute contraindication to diving, others think it to not be a significant problem. The migraine following a dive might be difficult to distinguish from decompression sickness and can possibly be provoked by CO2 retention in a diver.

Dangers

Because migraine can cause fainting in adolescents, the loss of consciousness would be particularly dangerous underwater. It can also cause severe vertigo, nausea and vomiting and can be produced rapidly by swimming.

Migraine with neurological symptoms or signs is a definite contraindication in the commercial diver.

Migraine may be precipitated by a rise in barometric pressure, among a host of other things. Medications taken for migraine also might have adverse effects on the diver.

Migraine with aura has been found to be significantly associated with patent foramen ovale, thought to be a factor in the causation of undeserved decompression accidents. Information about this can be found at the following reference:

Neurology 1999 May 12;52(8):1622-5
Potential source of cerebral embolism in migraine with aura: a transcranial Doppler study.

Diver’s Alert Network has the following to say about migraine and diving:
“A migraine headache is a periodic, usually one-sided, throbbing ache, sometimes preceded by warning signs and symptoms and of variable severity.

Migraine, though dreaded, is common. More than half the people in the world will have some experience with migraine during their lives, and about 5 percent will see doctors. A few of these will suffer significant disruption of their activities.

Fitness & Diving: Migraine poses little danger to divers. Even those with frequent migraine do not usually experience an increased incidence while diving. An elevated level of carbon dioxide in the blood, which occurs with decreased ventilation and breath-holding / hypoventilation, can theoretically precipitate a migraine headache because carbon dioxide (CO2) causes vasodilation in the brain. Increased levels of oxygen in the blood (which occurs in diving as well as in hyperbaric chambers) has been used with variable success to treat severe migraine, because it is a powerful brain vasoconstrictor.

Very complex migraine, with visual loss or paralysis, might lead to confusion in diagnosing a diving accident. However, little data exists to suggest that migraine poses a significant hazard to divers. Severe and incapacitating migraine headaches while in the water would create a hazard for the individual. People with severe and incapacitating migraine should probably not dive.”

Other headaches that might be seen with scuba diving.

Indo T, 1990
Swimmer’s migraine.

Headache 30(8), 485-487 (1990)
Indo T, 1989
Swimming induced vascular headache

Rinsho Shinkeigaku 29(7), 876-879 (1989)
Kim JS, 1992
Swimming headache followed by exertional and coital headaches.

J Korean Med Sci 7(3), 276-279 (1992)
Mizoguchi K, 1990
Benign exertional headaches induced by swimming.

Kurume Med J 37(4), 261-263 (1990)