Dr Peter Wilmshurst has been a qualified doctor for over 25 years. He has served on the BSAC Medical Committee since 1977 and also advises the HSE on diving.
Worried about your ears
Yes, you recognised it of course - a healthy human eardrum. But ear problems can ruin your diving, and this month the Diving Doc tackles a spate of questions on this delicate mechanism.
 I have been diving for three years, recently about four times a week. Last month while diving everything seemed OK, but when I surfaced I felt extremely dizzy, and was vomiting for two days. I had to stay in bed in the dark for about five days and at home for another ten. This happened once before. An ear specialist told me not to dive as I had a defective balancer, and nothing could cure the problem. Is this true Ramon.
The symptoms described are most likely to be the result of alternobaric vertigo. The inner ear is involved in balance as well as hearing. It is separated from the middle ear by membranes covering the round and oval windows.
Pressure on these membranes stimulates the balance mechanism. Symptoms of alternobaric vertigo occur when the pressure acting on these membranes in one ear is different from that in the other, so that one inner ear is stimulated more than the other.
This causes the balance mechanism to make the brain think the individual is spinning, producing rotational vertigo, jerky ear movements called nystagmus, and vomiting.
These symptoms occur during ascent when one middle ear clears more easily than the other. The usual cause is a problem with pressure release by one of the eustachian tubes that connect the middle ear to the back of the nose and allow us to equalise pressures in the ears.
A number of problems can occur. The sufferer might become disorientated or vomit underwater. Either could lead to drowning. Or the failure to equalise pressures might cause barotrauma in the ear, with the higher pressure in the middle ear causing it to rupture into another space. The rupture might be inwards towards the inner ear, and of a round or oval window, which can lead to deafness in that ear, permanent ringing in the ear, called tinnitus, or impaired balance.
Alternatively the middle ear might rupture outwards, perforating the eardrum. Therefore those who get alternobaric vertigo have an increased chance of suffering barotrauma in the ear.
No physical signs but...
I am an enthuastic novice diver, and have lost all hearing in my left ear, for no apparent reason, and been left with tinnitus. The medics I have been dealing with have drawn a blank but advised me not to do any more diving. My own doctor says it is a senso-neural problem and that as there is nothing physically wrong with the structures inside my ear he sees no reason why I shouldnt dive. Can I dive, and if so what do I need to do Martin.

We do not know the cause of the deafness and tinnitus in your case. It might be related to diving or might be coincidental.
However, it is clear that the function in one ear has been severely damaged. If you suffer a diving-related injury to your good ear, whether as a result of barotrauma or decompression sickness, you could become totally deaf and have unpleasant tinnitus in both ears.
There is also likely to be damage to the balance mechanism in one ear. If that mechanism in the other ear is damaged, you could find himself unsteady when walking, to the point of appearing drunk and even falling over.
The question you must ask is whether it is worth taking such a risk to continue diving.
Equalising difficulties
When I was doing my BSAC pool training I had difficulty clearing my ears even to 3m. On the open-water training it took up to five minutes to get down to 6m. When I went to the Red Sea I again had difficulty, particularly with the left ear, but took it gently. By the end of the week I was descending as fast as anyone else. However, I was left a little deaf for the next month, with my ears popping every now and then, and when they cleared I had residual tinnitus in the left ear. Am I the only one who has dived and had tinnitus as a result Will it ever go away and can I dive again Gill.

Persistent tinnitus after diving, particularly when there have been problems with ear-clearing, suggests that the diver might have suffered a rupture of the round or oval window.
Special investigations by an ear, nose and throat surgeon are needed to be certain. If this has occurred, urgent treatment - possibly an ear operation - might cure the symptoms, but if treatment is delayed, they are likely to be permanent.
The danger in diving again is that the same problem could affect the other ear.
Medication interaction
My wife suffers from complex migraine/tension headaches and was placed on Sertralin and Imipramine, which seem to control the pain reasonably well. Last year she dived to 20m without a problem. Now my 13-year-old son is being treated for depression with Wellbutrin and Prozac. My concerns for both of them are the same: is there a known or potential problem caused by interaction between compressed gases and these medications Jeff.
This letter raises many issues. Generally, when we consider whether an individual taking medication can dive we must consider both the medication and the illness that requires it.
There are certainly concerns about interaction between drugs that act on the brain and the effects of high partial pressures of nitrogen. We are concerned that nitrogen narcosis can occur at shallow depths, but unfortunately little information is available. Some of the newer antidepressants, such as Prozac, act on a brain transmitter called serotonin. This is also required for the function of platelets, the cells in the blood that cause clotting, and which are involved in decompression sickness.
In theory these drugs can affect susceptibility to decompression sickness, but again there is inadequate data. Many people have reservations about allowing some healthy 13-year-olds to dive, unless one is absolutely sure that they are mature enough to understand what is involved. I would not be happy to permit a 13-year-old who required antidepressant treatment to dive.
Complex migraines are also a problem, as these can be confused with decompression sickness. This might cause the sufferer to receive inappropriate treatment.
Epilepsy and try-dives
How should a club member responsible for organising pool try-dives respond to a request for such a dive from someone who claims to have epilepsy controlled on medication Helena.

Scuba diving, even in a swimming pool, can be hazardous for individuals with certain medical conditions. Diseases such as epilepsy and serious heart diseases can cause sudden unconsciousness that can lead to drowning. Individuals with significant lung disease can be at risk of pulmonary barotrauma even in a swimming pool, if they use scuba equipment. They should not be allowed to take part in pool try-dives.
Other people will not be permitted to progress to open-water diving, so it is unfair to whet their appetites with a pool try-dive.
So that individuals with these types of medical conditions are not permitted to participate in a try-dive, anyone wishing to take part should fill in a declaration of medical fitness.
They should declare that they do not have any of the diseases listed on the form. If they do, medical advice (usually from a medical referee) should be obtained before they are allowed to use scuba equipment, even in the pool.
Diabetes control 
I contracted diabetes mellitus three years ago, and need to inject before meals and at bedtime. I am checked every six months at my local diabetes centre and am always complimented on my control. Am I barred from enjoying diving despite this level of control Peter.
Diving clubs in the UK and certain other parts of the world allow some diabetics to dive. Some will be controlled with insulin injections, others take tablets, some are controlled by diet alone.
Any diabetic who wants to be considered fit to dive must demonstrate good control of diabetes and absence of complications such as heart or kidney disease that would indicate increased risk during diving.
In the UK, approval for a diabetic to dive is made by a medical referee after information about the diabetes has been received from his or her diabetic consultant and general practitioner.
The exact requirements are laid out in documents that can be obtained from the appropriate diving organisations.
Do I need a hep A jab
I have heard that divers in the UK should be immunised against hepatitis A. Is this true, and if so why Andrew.
Hepatitis A is a viral infection, and the virus is present in the faeces of infected people. Others become infected by faecal contamination of things that they swallow. Usually this results from contamination of food, but for divers it occurs if the water in which we dive is contaminated. Unfortunately much untreated sewage is dumped by the water companies straight into the seas, because it is the cheapest option. As a result divers are at risk of getting hepatitis A and are advised to be immunised against it.
Divers should also campaign for safer methods of sewage disposal (see Deep Breath in this issue).
Take heart
Im going diving for the first time and I have a condition called mitral valve prolapse, which means that the valves in my heart dont close properly. It doesnt bother me, and I have had a complete physical, but Im wondering if this will cause me problems when I dive. Jenni.

The mitral valve separates the left ventricle (the main pumping chamber of the heart) from the left atrium (its collecting chamber). In a lot of people this valve is a little more floppy than in others, and this allows it to bow backwards, which doctors call prolapsing.
Usually the valve bows only a little way back and there is little or no leak. The bowing back will however cause a doctor to hear particular sounds when listening with a stethoscope.
In fact about one person in ten has a mitral valve that prolapses, and 99 per cent of these people experience no associated complications and no significant leak.
In these cases my advice is to forget about the valve prolapse and consider the heart normal - as indeed it is. Diving is permitted without restriction.
It is only in those rare cases in which there is a lot of bowing back and the valve gets very leaky, or when even rarer problems arise, that diving may be restricted.