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Brain & Nervous System Health Center

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Coma: Types, Causes, Treatments, Prognosis

What Are the Different Types of Coma?

Types of coma can include:

  • Toxic-metabolic encephalopathy. This is an acute condition of brain dysfunction with symptoms of confusion and/or delirium. The condition is usually reversible. The causes of toxic-metabolic encephalopathy are varied. They include systemic illness, infection, organ failure, and other conditions.
  • Anoxic brain injury. This is a brain condition caused by total lack of oxygen to the brain. Lack of oxygen for a few minutes causes cell death to brain tissues. Anoxic brain injury may result from heart attack (cardiac arrest), head injury or trauma, drowning, drug overdose, or poisoning.
  • Persistent vegetative state. This is a state of severe unconsciousness. The person is unaware of his or her surroundings and incapable of voluntary movement. With a persistent vegetative state, someone may progress to wakefulness but with no higher brain function. With persistent vegetative state, there is breathing, circulation, and sleep-wake cycles.
  • Locked-in syndrome. This is a rare neurological condition. The person is totally paralyzed except for the eye muscles, but remains awake and alert and with a normal mind.
  • Brain death. This is an irreversible cessation of all brain function. Brain death may result from any lasting or widespread injury to the brain.
  • Medically induced: This type of temporary coma, or deep state of unconsciousness, is used to protect the brain from swelling after an injury. The patient receives a controlled dose of an anesthetic, which causes lack of feeling or awareness. Doctors then closely watch the person’s vitals. This happens only in hospital intensive care units.

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