Coma

Overview

Coma is a state of prolonged loss of consciousness. People in this state are not aware of their surroundings. Coma can have a variety of causes, including traumatic head injury, stroke, brain tumor, or drug or alcohol intoxication. It may even be caused by an underlying illness, such as diabetes or an infection.

Because coma is a medical emergency, quick action is needed to preserve life and brain function. Healthcare professionals typically order a series of blood tests and a brain scan to try to learn what's causing the coma so that proper treatment can begin.

A coma doesn't usually last longer than several weeks. People who are unconscious for a longer time might transition to a state of unresponsive wakefulness, previously known as a persistent vegetative state. Some people may ultimately experience brain death.

Symptoms

The symptoms of a coma commonly include:

• Closed eyes.
• Depressed brainstem reflexes, such as pupils not responding to light.
• No responses of the arms or legs except for reflex movements.
• No response to painful stimuli except for reflex movements.
• Irregular breathing.

When to see a doctor

A coma is a medical emergency. Seek immediate medical care for a person who is not conscious.

Risk factors

Risk factors for coma include:

• Serious head injury.
• Stroke.
• Bleeding in and around the brain, known as an intracranial bleed.
• Brain tumor.
• Serious infection, such as sepsis, encephalitis or meningitis.
• Near drowning, which decreases oxygen to the brain.
• Excessive use of alcohol or use of illegal drugs.
• Exposure to carbon monoxide, lead or other toxins.

Conditions that increase the risk of a coma include:

• Diabetes with blood sugar that's very high or very low.
• Serious hypothyroidism, also called underactive thyroid.
• Very low sodium in the blood.
• Heart failure, which can cause very low blood pressure.
• Epilepsy, including having seizures that last more than five minutes or that happen one after another without the person regaining consciousness.

The risk of coma goes up with age. This is especially true if older adults have a brain disease or another condition such as diabetes, high blood pressure or kidney disease. Older adults are also at risk of a coma if they take several medicines, which can lead to interactions or accidental overdose.

Complications

Many people gradually recover from a coma, but some may have complications that include major or minor disabilities. Others may enter a state of unresponsive wakefulness syndrome, previously known as a persistent vegetative state. Some people experience brain death and die.

During coma, bedsores, urinary tract infections, blood clots in the legs and other health issues may develop.