Coma

Coma is a medical condition in which a person completely loses consciousness, meaning they cannot be awakened even by painful or strong stimuli. A person in a coma typically has closed eyes and shows no voluntary responses, but other bodily functions such as the heart and breathing may continue to operate, sometimes assisted by medical equipment.

Coma is not a disease in itself but a symptom indicating that the brain has suffered damage or illness. Causes include head trauma, stroke (a blockage or rupture of blood vessels in the brain), blood sugar levels that are abnormally low or high, severe intoxication or drug overdose, brain infection such as meningitis, and oxygen deprivation to the brain when the heart stops.

Assessment

Doctors use a scale called the Glasgow Coma Scale (GCS), which assesses three things: eye opening, verbal response, and muscle movement. The score ranges from 3 to 15. A lower score indicates deeper coma. The doctor also examines pupil reflex by shining light, checks movement of each side, and uses imaging tests such as CT or MRI to identify where brain damage has occurred.

Treatment and care

Initial care consists of maintaining breathing, circulation, and brain fluid pressure, followed by treatment of the underlying cause. Patients are usually cared for in an intensive care unit (ICU). They are given nutrition through a feeding tube and the body is regularly repositioned to prevent bedsores and blood clots. Muscles are exercised to prevent them from becoming rigid.

Related conditions

It is important to distinguish coma from other conditions. In persistent vegetative state, a person has cycles of sleep and waking but has no conscious awareness. In minimally conscious state, there are faint signs of inconsistent awareness. In locked-in syndrome, a person has full mental awareness but cannot move the muscles except for the eyes. Medically induced coma is one brought about by doctors through medication to allow the brain to rest.

Prognosis and outcomes

Coma lasting longer than a few weeks rarely resolves to full recovery; most often it leads to partial recovery, a minimally conscious state, or death. Outcome depends on the person's age, the cause, how long the brain was deprived of oxygen, and how quickly treatment began. Some who recover may have lasting problems with memory, speech, or movement.