Coma: 10 Terms to Know

A coma is a prolonged and inadvertent (with the exception of a medically induced coma) state of unconsciousness. Comas can last a few days to many months -- and sometimes even years. Comas are probably more frightening for those around the patient, who can do very little and feel extremely helpless in such a situation. Here’s a look at 10 terms that can help you understand comas and feel a little more like a part of the cure.

1. Glasgow Coma Scale: The Glasgow Coma Scale provides a classification system for comatose patients. Patients score from a range of three to fifteen, depending on how they open their eyes, motor responses, and verbal responses. The goal of the scale is to provide a likelihood of recovery based on their response to external stimuli. It also provides a means of explaining and discovering the amount of consciousness the unconscious patient has retained. 
2. Ranchos Los Amigos Scale: This is a scale based on eight different levels of a patient’s response to external stimuli. In particular, it measures the levels of awareness, cognition, behavior and interaction with the environment.
3. FOUR Score: The FOUR score was developed by Mayo Clinic doctors as an alternative means for classifying neurocritical patients. Comatose patients score between zero and sixteen (zero being the worst, sixteen the best), based on their eye and motor responses, breathing patterns, and brainstem reflexes. The FOUR score was developed because the Glasgow Scale is largely useless for patients with an endotracheal tube, because these breathing tubes make verbal responses nearly impossible. 
4. Reticular Activating System (RAS): Comas are often caused by traumatic brain injuries that cause the brain to swell -- although a variety of other issues can cause this swelling as well. Once the brain becomes swollen, it can push on the brainstem, causing damage to the RAS. The RAS is a system of nerves that connect to the spinal cord and other parts of the brain, regulating wakefulness and the transition between consciousness and unconsciousness. 
5. Hypoxia: Another cause of comas is a condition known as hypoxia, often a symptom of other issues. Hypoxia occurs when the brain isn’t getting enough oxygen. This may happen during drowning or choking, as well as a heart attack or other traumatic event that interferes with the normal breathing cycle and the amount of oxygen in circulating blood. This lack of constant oxygen interferes with brain activity and can result in a number of other symptoms including memory loss, motor debilitation, focal interference, seizures, and death. 
6. Amnesia: Because comas are the result of severe brain trauma, memory loss often occurs in tandem. Although the media often depicts this is a long-term inability to remember anything about one’s life, the reality is that memory loss occurs more commonly from the time the injury occurred through consciousness, although it is possible to damage the brain sufficiently to lose a large portion of your memories -- or the ability to form new memories. 
7. Persistent Vegetative State: Perhaps the most frightening aspect of a coma is the potential to enter into a persistent vegetative state. At this point, there is no sign that the patient has any awareness of any verbal remarks or painful stimuli. Effectively, the only thing keeping someone in a persistent vegetative state alive is medical machinery. 
8. Brainstem Reflexes: Certain reflexes (unconscious responses) are controlled by the brainstem -- the tubelike structure that comes out of the base of the brain. These reflexes play a large role in determining the state of a comatose patient. Reflexes controlled by the brainstem include eye movements (blinking, pupil dilation, and other reflexes), coughing, gagging, and certain jaw reflexes, among other things. 
9. Spinal Tap: Certain infections, such as encephalitis or meningitis, can cause comas, so it is important to check for these if the cause of the coma is not obvious (like a traumatic brain injury). A spinal tap, or lumbar puncture, allows medical staff to check for these infections that lurk in the nervous system. A long, thick needle is inserted into the spinal column, removing some of the fluid contained there to be analyzed for infection. 
10. Electroencephalography: This is a type of brain scan that allows doctors to see how much electrical activity is going on in a comatose patient’s brain. Electrodes are attached to the head and a small amount of electricity is then sent through the electrodes. The electrical impulses that result are measured and recorded, allowing medical staff a visual of brain activity.