(See also Acquired Brain Injury, Stroke)
Coma is a state of unconsciousness in which a patient does not react with the surrounding environment. Someone who is in a coma is unconscious and has minimal brain activity. It is not possible to wake a coma patient using physical or auditory stimulation. They're alive, but can't be woken up and show no signs of being aware.
The person's eyes will be closed and they'll appear to be unresponsive to their environment. They won't normally respond to sound or pain, or be able to communicate or move voluntarily. Additionally a person in a coma fails to respond normally to painful stimuli, light, or sound; lacks a normal sleep-wake cycle and, does not initiate voluntary actions, being unable to consciously feel, speak, hear, or move.
Someone in a coma will also have very reduced basic reflexes such as coughing and swallowing. They may be able to breathe on their own, although some people require a machine to help them breathe.
Over time, the person may start to gradually regain consciousness and become more aware. Some people will wake up after a few weeks, while others may go into a vegetative state or minimally conscious state (see recovering from a coma, below). Coma patients can exhibit different levels of unconsciousness and unresponsiveness depending on which brain regions have been damaged and how much or how little of the brain is functioning.
Coma may result from; intoxication (eg drug abuse, overdose or misuse of medications), metabolic abnormalities, central nervous system diseases, acute neurologic injuries (eg stroke, hernia, hypoxia, hypothermia) or traumatic injuries caused by falls or vehicle collisions etc. In some instances, coma may be deliberately induced using pharmaceutical agents in order to preserve higher brain functions following brain trauma, or to save the patient from extreme pain during healing of injuries or diseases.
Initial treatment will depend on the cause of the coma and will be directed at preventing further damage to the brain. In the short term, a person in a coma will normally be looked after in an intensive care unit (ICU). If the patient is having difficulty breathing, he or she may be placed on a respirator while the underlying cause is treated. After a head injury, surgery may be required to stop bleeding and/or reduce swelling. If there is an underlying illness, or poisoning, then treatment will be directed at the underlying cause. The patient’s respiration and circulation must be monitored and maintained, using intubation and ventilation. Intravenous fluids or blood and other supportive care must be provided as needed.
Once stable and no longer in immediate danger then further treatment will be directed at maintaining the patient’s physical condition and preventing complications. For example, this could involve providing adequate nutrition, and preventing infection (e.g. pneumonia, bed sores). In the longer term, healthcare staff will give supportive treatment on a hospital ward. This can involve providing nutrition, trying to prevent infections, moving the person regularly so they don't develop bedsores, and gently exercising their joints to stop them becoming tight.
A person in a coma may become restless, requiring care to prevent them from hurting themselves or attempting to pull on tubes or dressings. In these instances, medicine may be given to calm the patient. Side rails on the bed should be kept up to prevent the patient from falling. While not empirically validated, families have reported benefits from arousal regimes, such as those implemented by Dr Ted Freeman (eg Coma Arousal Therapy). The therapy involves family members taking the patient through a regimen of controlled auditory, visual and physical stimulation for up to six hours a day every day.
Prognosis (outlook for recovery)
Comas can last from days to weeks while some severe cases have lasted several years. Recovery from a coma depends, to a considerable extent, on the original cause of the coma and on the severity of any brain damage. Some patients (e.g. patients in a diabetic coma) will make a complete recovery while others, particularly those who have suffered a head trauma, may have some physical, intellectual or psychological impairment that will require further treatment. They may need physiotherapy, occupational therapy, psychological assessment and support during a period of rehabilitation and may need care for the rest of their lives.
The chances of someone recovering from a coma largely depend on the severity and cause of their brain injury, their age and how long they've been in a coma. It's impossible to accurately predict whether the person will eventually recover, how long the coma will last and whether they'll have any long-term problems.
Patients can gradually come out of the coma, some progress to a vegetative state (aka unresponsive wakefulness syndrome) and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness (see Minimally Conscious State). The likelihood of significant functional improvement for coma patients diminishes over time.
Further Information and Support
For information about Coma Arousal Therapy, see Dr Edward (Ted) Freeman (1987) The Catastrophe of Coma. Publisher: David Bateman
Brain Injury Australia
Coma Science Group (Belgium)
National Institute of Neurological Disorders and Stroke (USA)
ComaCare (South Africa)
Brain Injury Resource Center
Reviewed February 2017 by: Shannan Keen, MBMSc, Brain and Mind Research Institute, University of Sydney