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
Last reviewedNovember 2014by Rimas Lukas, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.