What Is Coma?
A coma is a deep state of unconsciousness during which a person's brain is still alive but the person is unable to respond to his or her environment or stimulus. A coma is the result of a serious illness or illness complication, or as the result of a traumatic head injury. When a person goes into a coma, it is possible that he or she will lose higher brain functioning and not be able to come out of the coma. A person can live in a coma state for days, weeks, months, or even years. Vital functions such as circulation and breathing often remain mostly intact.
A person in a coma may have occasional movement including facial movements, eye movements or opening, and/or limb movement; however, the coma state indicates that the person is non-responsive and that he or she will not respond to commands. There is some research to suggest that people can hear while in a coma state, and that they remember spoken conversation upon exiting the coma state.
What Causes a Coma to Occur?
Comas are caused by a number of circumstances, including the following:
- Traumatic head injury - such as traffic accidents, violence, falling, or sports injuries
- Complication of concussion
- Stroke - acute blood flow loss to the brain, swelling
- Brain tumor - pressure and swelling in the brain
- Drug or alcohol intoxication
- Drug or alcohol overdose
- Lack of oxygen - lack of oxygen shuts down the brain
- Illness - such as encephalitis and meningitis cause inflammation and infection in the brain
- Spinal cord injuries
- Diabetes - too high or too low blood sugar levels
- Toxins - such as carbon monoxide
When a person enters a coma, action must be taken immediately to preserve and maintain necessary body functions. The symptoms of a coma vary, but typically include:
- Closed eyes
- Non-responsive "brain stem reflexes" such as dilating pupils
- Unresponsive limbs
- No response to pain
- Irregular breathing
When a coma is suspected, doctors review the events immediately preceding the coma, the patient's medical history, changes in health or behavior, and drug or alcohol history.
A physical examination is then conducted, wherein reflexes, pain stimulus and other stimulus will be tested, checking for a response in the body or in eye movements. Coma differs from unconsciousness in that a person may still have eye movement responses.
Blood and spinal fluids may be tested for infection, poisoning, drugs, or other potential causes of the coma. Brain imaging may also be used to monitor brain activity or injury.
Glasgow Coma Scale:
Glasgow Coma Scale (GCS) is a neurological scale that tries to give a reliable, objective way to record the conscious state of a person for assessment. The GCS is used to assess level of consciousness after head injury, acute medical trauma and monitoring those in intensive care.
The scale is composed of three tests: eye, motor, and verbal. The values applied to these tests is applied separately and as their sum. The lowest possible score is 3 and highest is 15.
Treatment of Coma:
A coma is treated in a number of ways.
The first step is to remove the individual from immediate danger from illness or injury. Once the person is relatively stable, health professionals will then treat the individual preemptively for infection and pneumonia, in addition to managing bed sores and nutrition to promote recovery as much as possible. It is important to maintain a healthy body in the individual as much as possible, including stimulating muscles, moving limbs, and maintaining regular body functions.
Outcome for Coma Patients:
Coma outcomes vary greatly depending upon the initial cause of the coma. Other factors affecting coma outcome include injury or illness that occur post-coma, brain damage, and trauma. If the coma is due to a medical condition, treatment of the medical condition may lift the coma. Similarly, if the coma is due to injury, the coma may lift as the injury heals.
While a coma typically lasts for two to four weeks, it is possible for comas to persist for months or years. Most often, if a person in a coma dies, he or she dies from secondary infection.
It is unlikely that a person in a coma for more than three years will ever wake up again.
What is Brain Death?
The brain can survive approximately six minutes after the heart stops. (One of the reasons to learn CPR is that if CPR is begun within six minutes following cardiac arrest, the brain may survive. After six minutes without CPR, the brain begins to die.) Resuscitation allows the doctor time to assess and treat the damaged brain. Medication and mechanical ventilation allow for tissue oxygenation, but severe brain damage or a prolonged period without oxygen or glucose causes death of the brain.
Brain death is when the entire brain – including brain stem – has irreversibly lost all function. Legal time of death is when a physician determines that the brain and the brain stem have irreversibility lost all neurological function.
Brain Death Versus Coma?
People who suffer brain death are not in a coma, and people in a coma may or may not progress to brain death. People in comas will still exhibit some variable neurological signs. Any electrical impulse leaving the brain in reaction to an external stimulus is a sign that a person is in a coma. People who suffer brain death will not exhibit these signs.
Deep Coma Versus Persistent Vegetative State?
People in a coma may be in a deep coma or a vegetative state. A person in a coma usually requires hospital care, while a person in a vegetative state may be released to at-home family care. A person in a vegetative state has much lower-brain function and a bit more upper brain-stem function than one in a deep coma.
People in vegetative states or deep comas are legally considered alive.
Additional Coma Resources:
The National Institute of Neurological Disorders and Stroke - provides a general description of coma and a brief indication of treatment and current research.
Coma/Traumatic Brain Injury Recovery Association - is a support group for those with, have had, or survive others who have suffered from TBI or coma. The website contains research, information, and support.
Brain Injury Association of America - Another resource for information and research, including media and advocacy for brain injury and related issues.