Stroke, or loss of blood supply to the brain, causes damage to part of the brain, or bleeding from a blood vessel in the brain, which results in similar injury. Strokes come in all sizes and shapes, and the resulting disability depends on size and location of the event.
Fitness & Diving:
1. Most strokes occur in older people. The stroke itself identifies the person as one who has advanced arterial disease, thus a higher expectation of further stroke or heart attack.
2. The extent of disability caused by the stroke (e.g. paralysis, vision loss) may determine fitness to dive.
3. Vigorous exercise, lifting heavy weights and using the Valsalva method for ear-clearing when diving all increase arterial pressure in the head and may increase the likelihood of a recurrent hemorrhage.
4. While diving in itself entails exposure to elevated partial pressures and elevated hydrostatic pressure, it does not cause stroke.
5. There is certainly increased risk in diving for someone who has experienced a stroke. Exceptional circumstances may exist, such as cerebral hemorrhage in a young person in whom the faulty artery has been repaired with little persisting damage. This type of recovery may permit a return to diving, with small risk. Each instance, however, requires a case-by-case decision, made with the advice of the treating physician, family and diving partners. Consulting a neurologist familiar with diving medicine is also advisable.
6. There is a similar concern for significant residual symptoms, as with post brain tumor surgery.
(Hugh Greer MD, Alert Diver, May-June 1999.)