It is extremely important for a physician to quickly determine the cause of a coma, so that potentially reversible conditions are treated immediately. For example, an infection may be treated with antibiotics, a brain tumor may be removed, brain swelling from an injury can be reduced with certain medications. Furthermore, various metabolic disorders can be addressed by supplying the individual with the correct amount of oxygen, glucose, or sodium, by treating the underlying disease in liver disease, asthma, or diabetes, and by halting seizures with medication.
Some conditions which cause coma can be completely reversed, restoring the individual to his or her original level of functioning. However, if areas of the brain have been sufficiently damaged because of the severity or duration of the condition which led to the coma, the individual may recover from the coma with permanent disabilities, or may never regain consciousness. Take the situation of someone whose coma was caused by brain injury in a car accident. Such an injury can result in one of three outcomes. In the event of a less severe brain injury, with minimal swelling, an individual may indeed recover consciousness and regain all of his or her original abilities. In the event of a more severe brain injury, with swelling which results in further pressure on areas of the brain, an individual may regain consciousness, but with some degree of impairment. The impairment may be physical, such as paralysis of a leg, or result in a change in the individual's intellectual functioning and/or personality. The most severe types of brain injury result in states in which the individual loses all ability to function and remains deeply unresponsive. An individual who has suffered such a brain injury may remain in a coma indefinitely.
Outcome from a coma depends on its cause and duration. In drug poisonings, extremely high rates of recovery can be expected, following prompt medical attention. Patients who have suffered head injuries tend to do better than patients whose coma was caused by other types of medical illnesses. Excluding drug-poisoning induced comas, only about 15% of patients who remain in a coma for more than a few hours make a good recovery. Adult patients who remain in a coma for more than four weeks have almost no chance of regaining their previous level of functioning. However, children and young adults have regained functioning after two months in a coma.