Dangers of Stroke When Diving
Divers face many risks when they plunge into the depths, and one risk is the threat of stroke and similar conditions. Educating yourself about the dangers and proper safe-diving techniques can help you avoid problems.
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Features
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Stroke occurs when a blood clot blocks an artery or a blood vessel breaks. This causes an interruption of blood flow to the brain, and brain cells begin to die as a result. When the cells die, you lose the ability to perform those functions the cells supported. In the United States, 144,000 people die each year from stroke, making it the third-leading cause of death. Ischemic stroke occurs when plaque or other fatty deposits block arteries. Hemorrhagic stroke occurs when a blood vessel in the brain breaks and blood leaks into the brain.
Identification
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Common stroke symptoms include sudden severe headache with unknown cause, sudden numbness or weakness in the face, arm or leg, sudden confusion, difficulty speaking and understanding, vision trouble and trouble walking, dizziness, and loss of balance and coordination.
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Conditions
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Arterial gas embolism occurs when a diver surfaces without exhaling and air becomes trapped in the lungs, where it can expand and rupture lung tissue. The rupturing of the tissue is called pulmonary barotraumas; it releases gas bubbles into the arteries. Since the brain receives the highest proportion of blood flow, it is the primary recipient of the bubbles, and the bubbles may interrupt circulation of blood flow to the brain as the bubbles become lodged in small arteries.
Considerations
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While not described technically as stroke, AGE is a sometimes deadly condition that can lead to brain damage and death from the lack of blood flow to the brain. Like stroke, symptoms include dizziness, visual blurring, numbness, disorientation, paralysis, convulsions and unconsciousness. In some cases, divers stop breathing, too.
Effects
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AGE is a serious concern for divers. It is responsible for 10 percent of all decompression illness cases each year, according to the Divers Alert Network. In the late 1980s, 18 percent of all decompression illnesses in divers took the form of AGE, but the numbers are much lower today, partly due to the advent of dive computers to help divers time their rate of ascent.
Theories/Speculation
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A 2001 study reported in the Journal of Occupational Health concluded that a group of Japanese divers who held their breath during a technique called free diving appeared to be at increased risk for cerebral injuries with symptoms similar to those common in stroke victims. The researchers discovered that 13 of 16 divers in the study had histories of stroke-like neurological symptoms. None of the divers had vascular disease nor risk factors for stroke. The symptoms occurred during or after repetitive deep dives.
According to information on the website for the Divers Alert Network, a forum for divers, a method divers use to clear their ears of water, called the Valsava method, is believed to increase arterial pressure in the head and can increase the likelihood of a recurrent hemorrhage among divers who have a history of strokes. The network says diving does not cause stroke, but it does expose individuals to elevated partial pressures and elevated hydrostatic pressure.
Prevention
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To avoid AGE, relax and breath normally during ascent. If you have conditions such as asthma, infections, cysts, tumors, scar tissue from lung surgery or obstructive lung disease, consult a physician before diving. Educate the physician about your technique and discuss the risks.
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References
Resources
- Photo Credit Historianurian/Creative Commons
