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Cardiovascular System - Stroke

Dr Jules Eden, dive medicine specialist and founder of e-med, answers divers' questions - as published in Sport Diver magazine:
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Q - I'm a character who has suffered a subarachnoid haemorrhage. The treatment was a 6 hour operation where they "cut my skull open" and made the repair. The vessel had popped in 3 places over 5 years but the final pop caused serious headaches which finally led me to hospital in a wrecked condition. Over the years prior to the final episode, I was diving a lot to depths of approx. 30m and had no idea that I was born with a weak vessel in the brain. Last September the vessel exploded and resulted in a major operation a day later. 7 months on and I have returned to work full time and feel good. I get the occasional skull aches but this is down to the "skull repairing". There are no other symptoms that worry me except the "who knows" theory. In simple terms Doctor, I want to dive again and have been advised to take a 12 month break. My dive club has said that I should seek further advice before diving.

A - Exploding blood vessels are never a good thing, but at least it didn’t happen on a dive – that could easily have been curtains. For the uninitiated, a subarachnoid haemorrhage is a bleed into the space between two of the three membranes that cover the brain. It classically appears as a “thunderclap” headache, sudden and severe, often causing vomiting, seizures or reduced consciousness. Most often the blood vessels are inherently weak and form “aneurysms”, thin-walled bulges that can burst without warning. Luckily these aneurysms can be clipped or coiled to prevent re-bleeding. You must have had clipping, as this involves opening the skull (a procedure called a craniotomy) to locate the source of bleeding, then placing clips around this area. Coiling involves the deployment of platinum coils in the aneurysm by feeding a catheter through a groin artery; a clot forms in the aneurysm, obliterating it. So, if we’re sure that your bleed was fixed and that you don’t have any other “ready-to-pop” aneurysms, then the prospects for diving are good. Clearly your skull needs to be devoid of holes, ie. fully healed up, and you need a full neurological check-up to ensure there are no residual deficits from the bleed. 12 months is about right; see your friendly local dive doc soon after for a medical.

Q - I am a diver who gave up smoking for 3 months and took to eating jelly beans instead and had to have a blood test which showed my blood sugars 'off the scale'. I stopped the sweets and went back to smoking (38 year habit) and a blood test a week later showed blood sugars as normal. I have not had a bad reading since then in 4 years so consider myself a 'developing diabetic'. Last Christmas I awoke to find myself blind in one eye, which lasted for approx 10 mins. Doctors have diagnosed this as a mini stroke (TIA) and given me ECG's, carotid artery scans etc, all of which came out as 'normal' but a check on my eyes last week showed restricted blood vessels in the back of the eye due to 42 years of smoking. The mini stroke clinic consultant likened diving to flying as it involved a change of pressure and advised me not to dive for 6 weeks. However, I would like your opinion before the season starts - I have been diving in the pool all winter - up to 2 metres only without any ill effects.

A - Well I think 6 weeks is about right after your TIA, provided you are fully back to normal, but from what you’ve said you are at quite high risk of a future problem. Smoking for that long (whether it’s 38 or 42 years, it’s still a very long time) will have furred up the pipes, caused significant lung damage and is likely to predispose you to high blood pressure. It’s good to hear your carotids are hunky-dory but the other test you need is an echocardiogram. This looks at the four chambers and valves of the heart. Sometimes little bits of clot form on the valves or in the chambers, which can fly off and cause further TIA’s or full-on strokes. While the pressure changes of diving don’t cause strokes in themselves, vigorous exercise, tank lifting and forceful equalising manoeuvres can all raise arterial pressure in the head and increase the risk of a TIA or stroke. And of course diabetes comes with its own set of dive-related issues. Basically I’d be pretty careful with the type of diving you do – try to keep depths and bottom times minimal and avoid situations where you are pushing your physical endurance. Pool diving is no substitute for the open water.

Q - My father is an ex-military diver, he is now 68 years old, but has kept up recreational diving for many years since he left the Navy. He has always been pretty fit but 6 months ago he had a stroke. He suddenly lost the use of his leg and his speech went. The hospital have been putting him through rehab and he is doing really well - speech is nearly back to normal and he can walk unaided now. I know how much he loves his diving and how good it would be for him to get back in the water, but is it safe?

A - I'm not usually partial to Americanisms but they have a vivid term for what we Limeys call a stroke – a "brain attack". It does evoke much more succinctly what is going on – a stroke is very similar to a "heart attack" of the brain, where blockage or bleeding of a blood vessel in the brain causes damage and loss of function. It also emphasises the urgency of treatment – again similarly to a heart attack, clot busting drugs can be administered in certain strokes and can massively improve outcome. The precise symptoms of a stroke depend on the portion of the brain that is damaged, but like a phoenix from the ashes it has an amazing ability to recover and circumvent injured areas.

You don't mention whether your father's symptoms came on soon after diving, but a cerebral arterial gas embolism (CAGE) can look exactly like a stroke - in this case the cause is an escaped gas bubble blocking a blood vessel. Usually this is apparent during or immediately after surfacing and symptoms are sudden. Resuscitation and recompression are the important emergency treatments here.

It sounds as though your father's recovery is proceeding well. My concern though is whether he is at risk of a further stroke. Obviously the hospital will try to control his risk factors as much as possible (treating high blood pressure, diabetes, high cholesterol, stopping smoking – note again the parallels with heart attack), but the fact is that having had one stroke he is more likely to get another. Individual assessment is important though: his general fitness and previous diving experience would count very much in his favour. If he regains full use of his leg and is able to hold a regulator comfortably in his mouth, then he might well be able to dive again. Is it safe? There is no yes or no answer to that, but if progress is good then the risks can be reduced to a potentially manageable level.

Q - I am a recreational diver and would like advice on the resumption of diving following a subarachnoid haemorrhage (SAH). 4 months ago I had an accident on my racing bike (bicycle) which was caused by the chain snapping. As a result, I went over the handle bars and struck the back of my head on the road (I was wearing a helmet at the time). I was unconscious for (I believe) a very short time. I was assisted on the road side by a passing doctor and rushed to A & E. Following a CT scan and assessment, it was considered that I had possibly suffered a SAH and was moved to the high dependency ward.

The following day I was given CT and formal angiography which showed a heavy bleed, although no aneurysm was detected. I did not undergo any surgery, clipping, nor did I require a coil to be inserted.

I remained in hospital for 18 days before a final formal angiogram. This was negative and I was discharged the following day. I was prescribed nimodipine for 21 days, together with pain relief as necessary.

My consultant advised rest for a few months but did not specify any restriction. I have returned to work and have resumed cycling and a normal life. I am an accountant.

A - Accountants do have the worst luck, don’t they? This strikes a bit of a chord with me. Most days I bike into work along the canal and I’ve had several near misses. I memorably terrified a small child recently by rising from the swampy mire like some algae-draped lagoon dweller, having skidded in after a similar chain-snapping mishap. A short anatomy lesson first: the brain is covered by 3 membranes, collectively called the meninges, the middle one being the arachnoid. So a subarachnoid haemorrhage means bleeding under this middle layer. Some bleeds are caused by head injury, others can be spontaneous (the so-called “thunderclap” headache, a sudden "most severe ever" pain developing over seconds to minutes). Most of these spontaneous occurrences are due to aneurysms (weak bulges) in the blood vessels of the brain, and if left they can rebleed at a later date. They are generally treated by clipping them off, or inserting little platinum coils which cause them to clot off and disappear.

But in your case the haemorrhage resulted from a bang on the head, and thorough investigations have not revealed any aneurysms which might potentially bleed again. So after this episode has fully settled (give it 3 months at least), and provided you have no complications, I would be happy for you to dive again.

(other dive medical questions)


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