By Frans Cronjé, Executive & Medical Director, DAN Southern Africa
Q: We have a boy in our class who is eager to dive but has an old history of epilepsy. This period was confined to a 12-month duration (1998-1999). His doctor subsequently completed a dive medical examination form, and the prospective diver indicated that he had experienced no further seizures since 1999. He has since gotten his driving license back from the DVLA (Driver and Vehicle Licensing Agency) and hasn't had to take any drugs since 2001.
The doctor seems confident that he is back to full health, but the young man would like confirmation that, despite his doctor's notes, that he is OK to dive. Can you give us any advice on this? I'm assuming that since his doctor has cleared him for diving and the DVLA has given him his driving license back, he should be OK to dive, but, if possible, I'd like to get a second opinion from you.
Many thanks for your time and help.
- A DAN Member in Africa
A: The issue of epilepsy (a condition demonstrated by the development of multiple seizures) and scuba diving is a complicated one. The primary concern is that a loss of consciousness underwater is likely to result in death by drowning unless, by a turn of good fortune, the individual:
Unfortunately, this is a long wish list to be met, and the death rate with unconsciousness underwater is between 30 and 70 percent. In the case of a seizure underwater, it may be even higher.
Diving induces many of the stimuli known to independently precipitate an epileptic seizure: flickering lights, hyper- or hypoventilation and sensory deprivation. So, if there is even a marginal risk for seizures, this may be further increased by diving.
Finally, even though an individual has not had epilepsy for a number of years or after a certain age, statistics still indicate that the probability of another convulsion is greater than in the rest of the "normal" diving population (believed to be less than 1 percent).
Certain training associations, such as the British Sub-Aqua Club, do accept medical clearance for individuals who have been seizure-free - on no medication - for five years, or after three years if the last seizure occurred during sleep only. This position, made by their medical advisory panel, is based on evidence that the chances of developing another seizure decreases exponentially over time and approaches near normal levels after five years. There are no data, however, that evaluate the risk specifically for the stresses of diving.
Ultimately, the diver must decide. Most diving physicians are very reticent to encourage an individual - with a known risk factor - to face an elevated or unquantified risk, for which the adverse outcome is likely to be fatal.
Two elements must be considered in summarizing the current recommendations concerning epilepsy and diving: First, that most diving physicians are of the opinion that unless the seizures or unconsciousness were due to:
(1) fainting with ultimate seizure activity due to remaining upright in the presence of low blood flow to the brain;
(2) other causes of acute low blood pressure, low blood sugar, medication or recreational drugs; or
(3) fever, but not after the age of 5, they would not feel confident about advising a person with a confirmed diagnosis of epilepsy that it would be safe to dive.
Second, that there is scientific evidence that suggests that individuals who have been free of seizures, without medication, are unlikely to have further seizures after a period of five years (see References). This encourages continued efforts to further our understanding of the relationship between epilepsy and diving.
For the moment, though, it seems that the prospective diver would not be considered fit to dive. After five years off medication, we may again be faced with this question.
2. Callaghan N, Garrett A, Goggin T. Withdrawal of anticonvulsant drugs in patients free of seizures for two years. N Engl J Med 1988. 318: 942-6.
3. Dreifuss FE. Epileptics and scuba diving. JAMA 1985. 253:1877-8.
4. Edmonds C, Lowry C, Pennefather J. Diving and subaquatic medicine. 3rd ed. Butterworth Heinemann, Oxford 1992 p470.
5. Shinnar S, Vining EP, Mellits ED, D'Souza BJ Holden K Baumgardner RA Freeman JM. Discontinuing anti-epileptic medication in children with epilepsy after two years without seizures. N Eng J Med 1985. 313: 976-80.
(c) DAN - Alert Diver March / April 2005