The Basics
Written by the doctors and editors at UpToDate � �
What is a coma? " � A coma is a deep state of unconsciousness. A person in a coma: � �
- Looks like he or she is asleep
- Cannot be woken up
- Cannot move at will
- Does not respond to pain or react when spoken to, touched, or shaken
People in a coma sometimes twitch, move a hand or finger, or make faces or sounds, but that does not mean they are aware, awake, or in control. � �
What causes a coma? " � A coma can be caused by anything that disrupts normal brain function. Some of the most common causes include: � �
- Head injury
- Stroke or bleeding in the brain
- Brain tumors
- Very low blood sugar or other chemical imbalances in the body
- Poisoning, or drug or alcohol overdose
- Lack of oxygen or blood to brain, which could happen if a persons heart stopped or the person almost drowned
- Infections such as meningitis or encephalitis
- Seizures
How do doctors find the cause of a coma? " � If a person is unconscious, his or her doctors and nurses will do an exam to see how the person responds to touch and pain, and to see how the person's eyes respond to light. Then, they will order tests, such as: � �
- Blood tests
- Imaging tests of the brain " � These tests create pictures of the brain and can show if any parts of the brain are damaged. Examples of these tests include CT scans and MRIs.
- EEG (which stands for electroencephalogram) " � An EEG measures the electrical activity in the brain. It can measure brain waves and shows whether a person is asleep or unconscious and whether they are having seizures.
- Lumbar puncture (also called a "spinal tap " �) " � For this test, a doctor puts a thin needle into the person's lower back and removes a small amount of spinal fluid. Spinal fluid is the fluid that surrounds the brain and spinal cord. The spinal fluid goes to the lab for tests.
How is a coma treated? " � The only way to get a person out of a coma is to reverse the condition that caused it. That is not always possible. If it is possible, it needs to be done right away to prevent death and permanent brain damage. � �
When it is not possible to get someone out of a coma, doctors try to at least make sure the person keeps breathing and still has a heartbeat. To do that, they hook the person up to machines that monitor heart rate and breathing. That way, the medical team can respond right away if anything goes wrong. Some people who are in a coma need to be put on a machine that breathes for them. � �
People in a coma also: � �
- Get medicines to help control basic body functions, such as blood pressure, heart rate, and body temperature
- Get fed through an IV (a tube that goes into a vein) or a stomach tube
- Get moved every so often so that they do not develop sores on their body
- Have routine blood tests done often, so the doctors and nurses can look for signs of infection or other problems
- Have their reflexes and responses to pain checked every so often
- Have their temperature checked
How long can a coma last? " � Most people who are in a coma come out of it in 2 to 4 weeks. Comas are not permanent and do not usually last more than several weeks. Patients either recover completely or partially, or die. � �
Some people with severe brain injury transition from a coma to something called a "persistent vegetative state. " � People in a persistent vegetative state have brain activity that suggests they go to sleep and wake up but otherwise seem like they are in a coma. � �
All topics are updated as new evidence becomes available and our peer review process is complete. � �
This topic retrieved from UpToDate on: Nov 04, 2014. � �
Topic 83678 Version 2.0 � �
Release: 22.8 - C22.208 � �
� � 2014 UpToDate, Inc. All rights reserved. � �
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