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The signs and symptoms of coma commonly include:

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

When to see a doctor
Coma is a medical emergency. Seek immediate medical care.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.

Many types of problems can cause coma. Some examples are:

• Traumatic brain injuries. Brain injuries that result from traffic collisions or acts of violence are the most common cause of comas.
• Stroke. Acute loss of blood flow to the brain followed by swelling or no blood flow to a major part of the brainstem can result in coma.
• Diabetes. Blood sugar levels that get too high (hyperglycemia) and stay too high or get too low (hypoglycemia) and stay too low can cause coma.
• Lack of oxygen. People who have been rescued from drowning or been resuscitated after a heart attack may not awaken due to lack of blood flow and oxygen to the brain.
• Infections. Encephalitis and meningitis are infections that cause inflammation of the brain, spinal cord or the tissues that surround the brain. Severe cases of either of these infections can result in coma.
• Seizures. Ongoing seizures may lead to coma.
• Toxins. Exposure to toxins, such as carbon monoxide or drug overdoses, can cause brain damage and coma.
• Intoxication. Overdosing on drugs, medication or alcohol can result in coma.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.

Although many people gradually recover from coma, others enter a vegetative state or die.

Complications that may develop during coma include pressure sores, bladder infections and pneumonia.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.

Coma is an emergency medical condition. If you are with a person who develops signs and symptoms of coma, call 911 or your local emergency number immediately.

When you arrive at the hospital, emergency room staff will urgently need as much information as possible about what happened before the coma. On the way to the hospital, try to pull together answers to the following questions:

• Did the coma start abruptly or gradually?
• Were there problems with vision, dizziness or numbness beforehand?
• Does the affected person have any history of diabetes, seizures or strokes?
• Did you notice any changes in the person's health in the time leading up to the coma, such as a fever or worsening headache?
• Did you notice any changes in the person's ability to function in the time leading up to the coma, such as frequent falls or confusion?
• What prescription or nonprescription drugs did the affected person use?

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.

Because people in coma can't express themselves, doctors must rely on physical clues and information provided by families and friends. Be prepared to answer a number of questions about:

• What happened leading up to the coma
• The affected person's medical history, including other diagnoses
• Recent changes in the affected person's health or behavior
• The affected person's drug use, including prescription and over-the-counter medications as well as illegal, recreational drugs

Physical exam
Doctors will check your reflexes, response to painful stimuli and pupil size. Squirting ice cold or warm water into the ear canals also can be informative. In unconscious people, these tests will cause reflexive eye movements of different types, depending on the cause of unconsciousness.

Laboratory tests
Blood samples will be taken to check for:

• Complete blood count
• Electrolytes, glucose and liver function
• Carbon monoxide poisoning
• Drug overdose

A spinal tap (lumbar puncture) can check for signs of infections. During a lumbar puncture procedure, a doctor inserts a needle into your spinal canal, measures the pressure and collects fluid for analysis. The entire procedure usually takes about 10 minutes.

Brain scans
Imaging tests help doctors pinpoint areas of brain injury. Tests may include:

• CT. A CT scan uses a sophisticated X-ray machine linked to a computer to produce detailed images of your brain. This is the best imaging test for assessing brain injuries because it can show a hemorrhage or brain tissue swelling. The scan takes only a few minutes.
• MRI. This scan uses a magnetic field and radio waves to generate images of the brain. You lie inside a cylindrical machine for 15 minutes to an hour. MRI scans are particularly useful for examining the brainstem and deep brain structures. Sometimes a dye is injected into your bloodstream during the procedure. The dye can help distinguish damaged brain tissue from healthy tissue.
• Electroencephalography (EEG). An EEG measures the electrical activity inside the brain. Small electrodes are attached to the scalp with paste or an elastic cap. The electrodes pick up the brain's electrical impulses, which are recorded on the EEG machine. This test can determine if you're having nonconvulsive seizures, which can cause comas.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.

Coma is a medical emergency, and attention first is given to maintaining respiration and circulation. Assistance with breathing, administration of fluids and blood, and other supportive care may be necessary.

Emergency personnel may administer glucose or antibiotics intravenously, even before blood test results return, on the chance that the person is in diabetic shock or has an infection affecting the brain.

Treatment varies, depending on what's causing the coma. Sometimes surgery is needed to relieve the pressure due to brain swelling. Other treatments may focus on addressing an underlying disease, such as diabetes, kidney failure or liver disease.

Sometimes the cause of coma can be completely reversed and the person will regain normal function. But if the brain damage is severe, the person may sustain permanent disabilities or may never regain consciousness.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.