Coma

What is a coma?

A coma is a lengthy deep state of unconsciousness. People in a state of coma are alive but are unable to move or be aware of or respond to their surroundings. They lose their thinking abilities but retain non-cognitive function and normal sleep patterns.

A person may appear fine, but will not able to speak or respond to commands. Spontaneous movements may occur, and the eyes may open in response to external stimuli. Individuals may even occasionally grimace, cry, or laugh. A coma rarely lasts beyond two to four weeks.

A coma may be the result of several conditions, including:

  • Traumatic head injury—A severe traumatic brain injury 
  • Stroke—A lack of or interrupted blood flow to the brain 
  • Lack of oxygen to the brain—Severe hypothermia, drowning, and stroke can interrupt oxygen to the brain
  • Infections—Encephalitis (inflammation of the brain) and meningitis (infection of the linings of the brain) 
  • Toxic substances to the brain—Toxins can include carbon monoxide poisoning or drug or alcohol overdose
  • A complication of an underlying illness, such as diabetes; sugar levels that are too high or low 
  • Repeated seizures

However, some people with coma enter a deeper state of unresponsiveness, or a persistent vegetative state, that may remain that way for years or even decades. Some people may face "brain death," in which there is no brain activity and key functions like independent breathing shut down. Removing assistive equipment at this point will lead to death.

Most people with coma eventually regain consciousness and recover gradually. Some individuals never progress beyond very basic responses, but many recover full awareness. Treatment is aimed at preventing pneumonia and physical therapy to prevent permanent muscle contractions and deformities of the bones, joints, and muscles that would limit an individual's recovery. Some people may have a combination of physical, intellectual, and psychological difficulties that need special attention.

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Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people in a coma?

If you or someone you know has been diagnosed with or recovered from a coma, consider enrolling in a clinical trial or brain bank. For information about brain donations, visit NIH NeuroBioBank.

Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with coma at Clinicaltrials.gov.

Where can I find more information about coma?

The following organizations offer information about coma and brain injuries:

Brain Injury Association of America
Phone: 703-761-0750 or 800-444-6443

Brain Injury Resource Center
Phone: 206-621-8558

Brain Trauma Foundation
Phone: 212-772-0608

Defense and Veterans Brain Injury Center
Phone: 800-870-9244

National Rehabilitation Information Center
Phone: 800-346-2742

ThinkFirst
Phone: 630-961-1400 or 800-844-6556

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