A coma is a state of prolonged unconsciousness that can be caused by a variety of problems — traumatic head injury, stroke, brain tumor, drug or alcohol intoxication, or even an underlying illness, such as diabetes or an infection. Maintaining alertness requires intact function of the cerebral hemispheres and preservation of arousal mechanisms in the reticular activating system (RAS—also known as the ascending arousal system)—an extensive network of nuclei and interconnecting fibers in the upper pons, midbrain, and posterior diencephalon. Therefore, the mechanism of impaired consciousness must involve both cerebral hemispheres or dysfunction of the RAS.
Disease Statistics in Japan: 0.02% (2,499) of hospital consultant episodes were for somnolence, stupor and coma in Japan for 2012-13.
Treatment for a coma depends on the cause.For example, if there is an infection that's affecting the brain, antibiotics may be needed. Glucose may be required in the event of a diabetic shock.
Surgery may also be necessary to relieve the pressure on the brain due to swelling or to remove a tumor. Major research on coma: coma patients in vegetative state may have damaged fiber connections in brain, making them aware but unable to respond.