Any form of unconsciousness under water is deadly with the attendant likelihood of arterial gas embolism and drowning. Epilepsy, even if well controlled, places you at great risk and one should not consider the possibility of diving. Illnesses such as asthmatics, diabetics and epileptics are conditions that could cause unconsciousness underwater even though controlled nicely on the surface.

Unconsciousness under the surface at depth is deadly and there is no such thing as a "little seizure" which could be tolerated, even if the person is "well controlled on medication." There is a clear medical risk involved and you should direct your energies and intelligence toward surface related activities.

Most diving medical people don't feel that any one with seizure activity of any kind should be certified as 'fit to dive'. The risks of having sudden seizure activity underwater are just too great. The regulator falls out of the mouth, there is a sudden intake of water into the lungs and the diver drowns. Compounding this is the fact that the diver then has to ascend in the water column - subjecting him/her to pulmonary barotrauma and gas embolism. In addition, one has to consider the increased risk placed on the diver's buddy and other divers in the group required to rescue the individual.

A second factor which has to be considered is the nature of the drugs used to control epilepsy, which are all, to some degree, sedative in nature and would thus exacerbate nitrogen narcosis or cause it to come on at an unexpectedly shallow depth. For this reason, there are medical practitioners who feel that it is also considered unsafe for any epileptic to dive if he/she is currently taking any anti-epileptic medication.

Further, it is well-known that hyperbaric conditions (a chamber dive or a 60 foot water dive) can cause a low percentage of seizures in individuals who do not have epilepsy (1% in US Navy studies). However, the effect of high partial pressures of oxygen on the person with controlled epilepsy is unknown.

Persons who have been seizure free for five years, on no medication and who choose to dive should be advised, in regard to the increased risk that hyperventilation and oxygen toxicity could precipitate seizures.

Individuals with controlled epilepsy, taking medication and seizure free for 2 years (meeting the requirements of most car-driving jurisdictions) are advised that if they ignore the recommendation not to dive - they have to accept the increased accident risk which is estimated to be 1.3 to 2 times that of the general population. It is also interesting to note that these same people who are allowed to 'drive' are not allowed to have a pilots license - nor are they allowed to perform commercial, scientific or military diving.

References
Dreifuss FE, 1985 Epileptics and Scuba Diving
JAMA 253(13), 1877-1878 (1985)

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