Overview

A coma is a state of unconsciousness where a person is unresponsive and cannot be woken. It can result from injury to the brain, such as a severe head injury or stroke. A coma can also be caused by severe alcohol poisoning or a brain infection (encephalitis). People with diabetes could fall into a coma if their blood glucose levels suddenly became very low (hypoglycaemia) or very high (hyperglycaemia). A comatose person exhibits a complete absence of wakefulness and is unable to consciously feel, speak, hear, or move.

Title
Coma

Types

- Toxic-metabolic encephalopathy: an acute condition of brain dysfunction with symptoms of confusion and/or delirium. The condition is usually reversible. The causes of toxic-metabolic encephalopathy are varied.

- Anoxic brain injury: a brain condition caused by total lack of oxygen to the brain. Lack of oxygen for a few minutes causes cell death to brain tissues.

- Persistent vegetative state: a state of severe unconsciousness. The person is unaware of his or her surroundings and incapable of voluntary movement.

- Brain death: an irreversible cessation of all brain function. Brain death may result from any lasting or widespread injury to the brain.

Medically induced coma: temporary coma, or deep state of unconsciousness, used to protect the brain from swelling after an injury.

Symptoms

The person in coma is unable to voluntarily open the eyes, does not have a sleep-wake cycle, and is unresponsive in spite of strong tactile (painful) or verbal stimuli.

Symptoms of a coma include the following:

- No response to outside stimuli such as:

    • Pain
    • Sound
    • Touch
    • Sight

- Spontaneous body movements such as:

    • Jerking
    • Shaking
    • Trembling
    • Eyes opening and closing
    • Irregular breathing
Causes

- Severe head injury, most commonly from:

    • Motor vehicle accidents
    • Violence
    • Falls

- Primary brain disorder

    • Brain tumor
    • Brain hemorrhage or stroke
    • Brain infection

- Lack of oxygen to the brain due to:

    • Very high blood pressure
    • Very low blood pressure or shock
    • Cardiac arrest
    • Severe seizures

- Severe general illness

    • Severe bodily infections
    • Severe acute liver or kidney failure
    • High carbon dioxide levels
    • Carbon monoxide poisoning
    • Toxicity from medication, alcohol, or illegal drugs
    • Abnormal hormone levels, such as from the thyroid or adrenal gland
    • Abnormal blood chemistries, such as sodium or calcium
    • Very low or very high levels of blood sugar
    • Very low or very high body temperatures  
    • Severe nutrient deficiency
Diagnosis
Treatment

A coma is a medical emergency. Any unconscious person should be taken to the emergency room immediately.

- Emergency Treatment
Oxygen and intravenous fluids will be given and the person’s vital signs monitored closely. He or she may be put on a ventilator. Health professionals will work quickly to determine the cause of the coma and further treatment will depend on the cause.

Usually, glucose is given by IV in case low blood sugar is causing the coma. Nalaxone can also be given by IV if a narcotics overdose is suspected. Thiamine (vitamin B1) may be given with glucose if alcoholism or malnutrition is suspected. In some cases, surgery may correct the cause of a coma.

  • Ongoing Treatment

Once the person is stabilized, treatment will focus on providing adequate nutrition and preventing infections and bedsores.

Prevention

Depends on the cause of the coma. The following can help decrease the risk of coma:

- Wear a seatbelt and make sure infants and small children are securely fastened in a child safety seat.

- Children age 12 years and under should ride in the back seat of a vehicle.

- Wear an appropriate helmet while biking, rollerblading, or playing contact sports.

- Wear athletic mouth guards while playing sports.

- Don’t abuse alcohol or drugs.

- If you have diabetes, see your doctor regularly and take appropriate steps to regulate your blood sugar levels.

If you are ill or take medicine, see your doctor regularly for check-ups.

Complications

Although many people gradually recover from a coma, others enter a vegetative state or die. Some people who recover from a coma may have major or minor disabilities. Complications may develop during a coma, including pressure sores, bladder infections, blood clots in the legs and other problems.

Risks

Risk factors for coma include:

- Severe illness

- Diabetes

- Liver, kidney, or cardiovascular disease

Risk factors for brain injury include:

- Age: 5 years or younger, 15-24, and 75 or older

- Sex: Male

- Traveling in a vehicle at a high rate of speed or at night

- Lack of sleep

A previous head injury

Recovery

People may emerge from a coma with a combination of physical, intellectual, and psychological difficulties that need special attention. Recovery usually occurs gradually—patients acquire more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Regaining consciousness is not instant: in the first days, patients are only awake for a few minutes, and duration of time awake gradually increases. Predicted chances of recovery are variable owing to different techniques used to measure the extent of neurological damage.

The most common cause of death for a person in a vegetative state is secondary infection such as pneumonia, which can occur in patients who lie still for extended periods.

Living with

Comas can last from several days to several weeks. In more severe cases a coma may last for over five weeks, while some have lasted as long as several years. After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness. Others remain in a vegetative state for years or even decades (the longest recorded period being 42 years). The outcome for coma and vegetative state depends on the cause, location, severity and extent of neurological damage

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