A person in a coma does not experience reactivity or perceptivity. The patient can not be aroused by calling their name or experiencing pain. The main symptom of a coma is the inability to be aroused to consciousness. A coma can be caused by a variety of things. The most often cause of coma is severe head injury.
Treatment varies depending on the cause.
When damage has occured, bleeding in the brain, swelling and congestion of the damaged tissue is pressent. In extreme cases, brain swelling is so great that portions of the brain must be forcible squeezed out of the skull. An alternative to squeezing portions of the brain out of the skull is to saw off the skull and place it in a cold storage to better accommodate the swollen brain. There are different stages of a coma. Most people believe that a person in a coma is in a deep sleep.