Causes

Normally, information from a person’s surroundings is passed from the brainstem into the cerebrum. This feedback allows a person to be conscious of and react to his environment. When this system breaks down and a person is no longer able to respond, a coma can result.

Brainstem and Cerebrum

© 2009 Nucleus Medical Art, Inc.

A coma may be caused by:

• Severe head injury, most commonly from:
  • Motor vehicle accidents
  • Violence
  • Falls
• Primary brain disorder
  • Brain tumor
  • Brain hemorrhage or stroke
  • Brain infection
• Lack of oxygen to the brain due to:
  • Very high blood pressure
  • Very low blood pressure or shock
  • Cardiac arrest
  • Severe seizures
• Severe general illness:
  • 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

Risk Factors

Risk factors for coma include:

• Severe illness
• Diabetes
• Liver, kidney, or cardiovascular disease
• Tendency to have blood clots
• Exposure to poisonous substances (eg, carbon dioxide)
• Cancer and chemotherapy

Risk factors for brain injury include:

• Age: 5 years or younger, 15-24 years old, and 75 years or older
• Sex: male
• Traveling in a vehicle at a high rate of speed or at night
• Lack of sleep
• A previous head injury