A coma is a state of deep unconsciousness that a person cannot be woken from. A person in a coma cannot react to events in the environment.

Information about your environment is normally passed from the brainstem into the rest of the brain. This feedback allows a person to be aware of and react to the environment. A coma is caused by a breakdown in this system.

Brainstem and Cerebrum
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The system may be interrupted by:

  • Severe head injury—most often a result of car accidents, violence, or falls.
  • Brain illness such as:
  • Lack of oxygen to the brain which may be due to:
  • Severe general illness such as:
    • Severe bodily infections
    • Severe acute liver or kidney failure
    • High carbon dioxide levels
    • Carbon monoxide poisoning
    • Toxicity from poisons, medication, alcohol, or drugs
    • Abnormal hormone levels, such as from the thyroid or adrenal gland
    • Abnormal blood chemistries, such as sodium or calcium
    • Very low or very high levels of blood sugar
    • Very low or very high body temperatures
    • Severe nutrient deficiency
    • Liver failure
    • Kidney failure
    • Inherited metabolic diseases