DIVE DOCTOR: Medical Q&A
Q: Earlier this year I suffered two major attacks of pain in my face ( jaw mainly), for no apparent reason. My doctor has diagnosed me with trigeminal neuralgia. I was taking 1,000 – 1,200mg of Tegretol daily and still not pain free. If I missed my medication, even just by a couple of hours, the pain would increase considerably. Funnily, I did find quite a lot of relief from the pain when I went swimming and diving. I believe this could be due to the cold water hitting my face and the blood vessels constricting, thus not irritating the nerve. The relief was amazing - I did not realise how much the constant pain was affecting me. Anyway, I was referred to a specialist neurosurgeon who confirmed I had the condition. Two months ago I underwent MVD surgery, where a blood vessel was found to be irritating the trigeminal nerve. Now I am down to 400mg of Tegretol daily and I have stopped taking all pain killers. So my question is: when I can safely get back in the water?
A: Trigeminal neuralgia goes by some wonderfully colourful synonyms, ‘tic doloureux’ and ‘suicide disease’ to name but two; indeed, Edvard Munch’s ‘ The Scream’ is said by some to depict one sufferer in the throes of an attack. The pain is intense, reputedly to be among the worst known, and several theories exist as to its origin. One particular explanation that has gained considerable traction in recent years is that which you appear to have: an enlarged blood vessel - possibly the superior cerebellar artery - compressing or throbbing against the microvasculature of the trigeminal nerve near its connection with the pons in the brainstem. MVD (or Microvasculardecompression) surgery is usually tried where medical treatments (such as Tegretol, or carbamazepine) have failed, and has produced amazing results, although there is a risk of post-operative facial numbness. Injecting glycerol and frying the errant nerve fibres with electrodes can also be effective. So, provided you have fully recovered from the MVD surgery, I don’t expect it will cause a problem. However, I am a little concerned about the carbamazepine as it has the potential to interact with dissolved nitrogen at depth, resulting in unpredictable and possibly dangerous side effects. Ideally you should wait until you’ve come off it fully before diving, but be aware it should not be stopped abruptly as this can cause seizures, so you need to discuss a weaning regime with your doctor.
Q: I wonder if you could help, I was given your contact details by a friend. Basically I was bitten by quite a lot of sea urchins a few weeks ago and while I did get medical treatment while I was there, my feet do not seem to be healing. I’ve been on antibiotics. My feet are still slightly swollen in patches and tender, parts are itchy and sore. I just wondered if this was normal, and whether I should be worried.
A: Sea urchins have a number of defence mechanisms, including a large array of venomous spines, long enough and sharp enough to pierce neoprene. Immediate treatment by immersing the area in hot water should denature the venom and provide some pain relief. Large spines should be removed with tweezers, and smaller fragments can sometimes be pummelled into submission, although if they persist they can cause inflammation and/or infection, giving you the typical symptoms you describe - redness, heat, tenderness, swelling, itching etc. Provided you are on antibiotics then you can treat the other symptoms with antihistamines, local creams (eg. calamine, hydrocortisone) and they should resolve, but this can take several weeks or even months. If the symptoms worsen, then see your GP again for review.
Dr Oliver Firth has gained considerable experience in the field of diving and hyperbaric medicine since joining LDC in 2006. He is an Approved Medical Examiner of Divers for the UK HSE, and a medical referee for the UK Sport Diving Medical Committee. He is involved in the management of all types of diving-related illness, including recompression treatment, as well as providing hyperbaric oxygen therapy for non-diving conditions. He remains a passionate diver and has participated in various expeditions and conservation projects throughout the globe.