“Illnesses that affect the brain and brain injuries can both cause comas.
“If a person suffers severe head trauma, the impact can cause the brain to move back and forth inside the skull.
“The movement of the brain inside the skull can tear blood vessels and nerve fibers, which causes swelling in the brain. This swelling presses down on blood vessels, blocking the flow of blood (and with it, oxygen) to the brain.
“The oxygen- and blood-starved parts of the brain begin to die. Some infections of the brain and spinal cord (such as encephalitis or meningitis) can also cause swelling in the brain.”
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