Dr Jules Eden, dive medicine specialist and founder of e-med, answers divers' questions - as published in Sport Diver magazine:
Q - I am about to complete my Dive Master course and will need an HSE medical to enable me to assist in training and supervision. I would like to ask about PFO. My 2 year old second cousin has just had surgery to repair this condition and I am told that this can be a genetic/hereditary disorder associated with focal migraines. I have been diving for 15 years, since I was 10. I have suffered from full focal migraines with aura (blurred vision, nausea, fuzzy lights, aversion to light, etc.) for most of my life, as have my dad and grandfather. I dive regularly, doing 20-30m dives both in the UK and abroad. I am relatively fit and active but am quite overweight (age 25, 5'5'', 15stone). I have never (touch wood) yet suffered from DCI. Should I get checked out for PFO before going for the medical exam? To what extent is the condition restrictive to diving once repaired?
A - PFO is such a common condition, and the actual number of bends so low, that screening everyone would be unethical – although the test is very safe, there are risks attached, and a large number of divers would end up requiring closure procedures unnecessarily. However, certain groups are thought to be more prone to PFO. Those who suffer migraines with aura are one. Aura is the term given to a neurological disturbance that precedes or accompanies your typical migraine headache. The commonest symptoms are visual disturbances (eg. zigzag lines, blurred or tunnel vision) but pins and needles, tingling, weakness, speech problems and even strange tastes or smells are possible. There is some evidence linking this type of migraine with the presence of PFO, and if you are keen on a career in commercial diving then one could make a case for screening to pre-empt a later episode of avoidable DCS. However, it has to be remembered that not all bends are due to PFO, so fixing the hole doesn’t make one “immune” to future bends. But once repaired, you’re carrying the same risk as a diver without a PFO, so you shouldn’t be discriminated against.
Q - Whilst on a dive last week I experienced visual disturbances akin to those which precede a migraine, ie. flashing lights and shimmering areas of vision. I used to suffer from migraines but haven't done so for many years. The visual symptoms went shortly after leaving the water. I had a similar experience last year after diving, but the symptoms were more severe. Then I put it down to exertion (I was new to diving and very nervous) and dehydration, but with it happening a second time, and especially with it happening under water, I am concerned it might have been a mild 'bend'. The dive itself was very relaxed, max depth 25m and I was only below 20m for about 10mins. Do you think this could have been a 'bend', should I go and see my GP, what should I do if it happens again, do you think it would be OK for me to dive again? I have been looking medical forums and the nearest I can find to visual disturbances seems to link with PFO. Any advice would be very gratefully received.
A - We’re impaled on the particularly spiky horns of a classic diving doc’s dilemma here: migraine or bend? Difficult to distinguish the two, as both can result in similar visual tomfoolery. The commonest eye-related DCS symptoms include blurring, tunnel vision and loss of parts of the visual field. These can also occur as part of the aura of a migraine, and as we know, headaches can be a presenting symptom of DCS. A tangled web indeed. Your unprovocative dive circumstances don’t ring DCS alarm bells, but we all know that a normal profile doesn’t exclude a bend. Other features unconnected with vision and headache (eg. joint pain) might lead one to suspect DCS, but you don’t mention any other symptoms. So my advice would be to see a neurologist about this before diving again. There are other conditions to consider, eg. TIA (Transient Ischaemic Attack, otherwise known as a “mini-stroke”), and as the symptoms have recurred and are worsening, you really need a full work-up to be sure what the cause is. An echocardiogram looking for PFO should be part of this.
Q - I've had a few episodes of odd visual disturbances after diving that I'd like to discuss with you. They are very intermittent, occurring only once or twice a year (and I'm diving most weekends), but usually involve my vision getting darker, almost like the lights being dimmed. Then I get coloured curves and zig-zags, and sometimes a headache. The eyes themselves are painless and don't appear red or inflamed at all. On one occasion I mentioned this to the boat crew and was given surface oxygen, which resolved everything in 20 minutes, so I never took it any further. It's happened twice since, and as I'm going to be doing some marine conservation work in the middle of nowhere for three months in the near future, I'm a little concerned. I would really like some reassurance that what I'm experiencing isn't serious!
A - Quite a bizarre set of symptoms there, but I’ll throw in my two pennies/cents. I’m presuming from your question that these episodes didn’t cause any problems in other organ systems, ie. they purely involved your vision. In which case, despite the apparent response to surface oxygen, we can put DCS and/or arterial gas embolism lower down on the list, as they tend to present with other manifestations too. We should consider simple things such as contact lens problems, medication side effects or local infections as well, as they can cause all sorts of visual disturbances. Typically though, they will be irritating or painful and involve watering or other surface reactions; not the impression I get from your description. My feeling is that these are probably migraine-like phenomena, which have been reported in the literature after exposure to pressure. These can be triggered by diving, or just happen as a coincidence, but are sometimes very difficult to distinguish from DCS. There is a well-publicised link between visual auras and patent foramen ovale (PFO, the “hole in the heart” that can predispose to DCS), which confuses the picture even further. As this is recurrent and you’re intending to dive for a long period in a remote location, my advice would be to get this fully checked out by a cardiologist with diving medicine experience before your trip.
Q - About four years ago I completed a normal profile dive and within an hour I experienced visual disturbances, with flashing lights and opaque sections of vision. At the time I was put on oxygen and after about 30 minutes my sight was fine. I suffered no other symptoms. After a couple of days I resumed diving with no problems.
However - and four years later - on a plane journey yesterday I was sitting at the front of the aircraft right next to the main door. On ascent, I experienced very similar visual disturbances - this time very specific, with arcs and triangles of red and yellow. Clearly this worried me, but it stopped about 25 minutes into the flight. My colleague said it was the first flight where he had experienced a very marked change in pressure. Although the episode passed I would like to know if the two incidents (although years apart - and I have flown many times since) are related, and if you have any advice to give me. I am not one to panic, but this has disturbed me somewhat!
A - They could well be related, but there are a few possible causes for these episodes. In the first case this could have been a symptom of DCI as it responded so well to oxygen. In the second, although cases of overt cabin depressurisation are unusual, a similar DCI could happen...
But there are a variety of other possible explanations. Migraine with visual symptoms is not uncommon and bizarrely doesn't always give you a headache. Your arcs, triangles and flashing lights do fit the criteria for migraine with aura, and migraine is often under- or misdiagnosed. Your GP might be able to help if you are getting more episodes. Occasionally floaters and flashing lights can signify an imminent retinal tear or detachment, so a visit to the optician should be top of your list as if caught early these conditions can be treated. There are a few weird and wonderful neurological problems that can present with visual hallucinations but most are rare. Importantly though, if it occurs again after a dive, then get some oxygen and call your nearest chamber.
Q - My question relates to migraine. I have had 5 episodes of migraine with visual aura +/- transient sensory loss in hand, two as a teenager, one pregnant, two when sudden drop in oestrogen from missing hrt, i.e. probably oestrogen related. No focal migraine now for about 3years and never needed prophylaxis medication. Is it safe to dive? Also a medical colleague suggested I needed an echo to check for a PFO, but have had no problems so far on 10 dives, to PADI open water levels. Is he scaremongering? Surely not all divers with migraine with aura need to undergo echo?
A - If you have been migraine free for 3 years, it sounds like diving should not be an issue. Also as you are not on any meds then all is fine as well. The issues with migraine and diving, is that if you were to get flashing lights, dots in your eyes, and a weird feeling in your head, then either you are an extra in "the Abyss", or you are about to vomit into your regulator. A dangerous thing at depth. So regular migraine sufferers, beware.
Now to PFO's. we all know the link between PFO's and unexplained hits at shallow depths, but there is also evidence to show PFO closure can help people who suffer these aura type migraines. But just as every diver with a PFO doesn't always get a bend, not every aura migraine is healed with closure. Get my drift. So as in life there is no 100% certainty.
I reckon the best thing to do is if the migraines ever return with a vengeance, or you do get a hit out of the blue, then have the transthoracic scan with bubbles that is used to diagnose this hole between the atria of a heart problem.
Q - I would like your advice on the issue of migraine.
I am 49 years of age; male, non-smoker, non drinker. I have had a recent diving medical exam and was passed fit to dive. I swim train 4 times a week and gym 3 times a week. My BP (at the last reading) is 125/76; pulse 56 at rest. Weight 85kg, height 5' 10".
I am a certified NAUI diver up to level Advanced Diver, have completed Assistant Instructor, but that certification has lapsed. I did one dive in April 2000, prior to that logged over 200 dives between 1981 and 1987. I am now wanting to re-enter scuba diving and have joined the local BSAC club with a view to starting again at the beginning so that I can be sure a) I am fit and capable, and b) that I am not missing out on any developments over the intervening years of non-diving.
Seven years ago I had two or three minor migraine attacks over a two week period. Cause unknown, but probably work/stress related. These attacks were minor in that there was no headache or spatial disorientation. The most severe symptom was pinwheel vision which cleared if I sat still with eyes shut for ten minutes or so. Since then, I have had no recurrence at all. Prior to that, (approx 1970) I had one migraine attack as described above while in the Army in 1970.
In your opinion, then, based on the information I have given, would you consider me precluded from scuba diving because of migraine?
A - No booz, no tabs. 7 times a week exercise. A blood pressure a Kenyan 1500 metre athlete would be proud of.But you've had a couple of migraines in the past, so are you fit to dive?
Well I think it's a huge YES for you. You are probably the fittest bloke who ever took to the water but sadly a victim of inflexible medical declaration forms. There is a point to not diving with migraines. If you have recurrent attacks and are at risk of having one on a dive then it may well be better that you don't go underwater. A throbbing headache, visual auras and paralysis are some of the consequences of this problem when it is severe. And getting this will risk a divers life if they are down in the deep. But yours are mild and haven't been back for many years. So I think you can declare yourself as fit to dive and well done on the health standards you set yourself. You put most of us other divers to shame.
A final point though for anyone with severe migraines. There is still a chance you can dive but you will need to discuss with an experienced diving doctor all the factors that trigger them. Also what treatment you are taking and what problems you really actually get. Anything that can occur underwater and risk you and your buddy sadly may well end in a ban until an effective treatment can guarantee they won't occur on a dive.