Coma - Fact Sheet

Coma is generally the result of damage or interference with particular structures of the brain. Length and depth of coma can provide a strong indication of the severity of injury to the brain.

What is a Coma?

During coma a person is in a state of unconsciousness. Individuals in coma do not show intentional response or movement or obey command, the eyes remain closed and individuals cannot be awakened during this state [1]. The person in coma may exhibit different levels of response to touch, pain, and verbal commands. It is therefore accurate to talk about depth of coma rather than thinking of coma as an all or none experience. Family members often have trouble accepting their loved one is in a coma when there are basic responses evident.

Coma is generally the result of damage or interference with particular structures of the brain. Specifically, areas of the brain responsible for arousal and awareness, including the cerebral cortex and brain stem [2]. A coma may also be chemically induced to accelerate healing, protect the brain from secondary damage or to relieve severe chronic pain during healing [1].

Some coma patients may progress to a wakeful but unconscious state called Post-Coma Unresponsiveness (PCU). This state was previously referred to as a Persistent Vegetative State (PVS), and this term is still used internationally. In this state the Cerebral Cortex of the brain is not functioning, and the person is unable to respond to stimuli in their environment, however they maintain a normal sleep-wake cycle and respiratory function [3]. Individuals can remain in this state for long periods of time. Once again this can be difficult for family members to accept, as the patient still displays some basic functions. For example, a patient’s eyes may follow them around the room. This is a very basic function of the brain, however it may appear as though the patient recognises people.

In the condition of locked-in syndrome, the patient appears unresponsive without the ability to move or verbally communicate, yet has full cognitive function. In this state the brain stem has been severely damaged. Such individuals are able to use an eye blinking response to communicate.

Coma Scales

There are two scales commonly used to measure the depth and duration of a coma. The most common is the Glasgow Coma Scale (GCS) which scores actions and reactions in three specific areas including eye, verbal and motor response (see scale at the end of this Fact Sheet). The scores in each area are sumed to give an overall score, ranging from 3 (deep coma) to 15 (fully awake). The Rancho Los Amigos Scale is another measure of coma, it has a single scale and assesses global functioning [4]. As it is not commonly used in Australia, details are not provided here.

Treatment during Coma

During coma the medical team will provide treatment and care to the patient to try and prevent any further complications. The initial treatment will focus on preventing any further damage to the brain. A respirator may be used to assist breathing and surgery may be required to stop any bleeding or swelling in the brain [5]. Constant monitoring of vital signs, such as blood pressure and pulse and levels of any prescribed medications will always take place [2].

Other therapies may be used to prevent problems upon awakening from coma. There is a risk of the patient losing their range of motion in their extremities, so the limbs will be moved regularly to avoid Spasticity (involuntary muscle tightness)[6]. Changing the patient’s position is necessary on a regular basis to prevent pressure sores or skin ulcers, as the patient will not have the reflex actions that prevent these sores from occurring as in someone who is just asleep [6].

Is a Person in a Coma Aware?

It is difficult to know if there is any degree of awareness during a coma. As the patient emerges from coma, awareness of those around them increases. There have been cases where patients reported awareness of family members around them and could remember some of what was said. For this reason families and medical staff should be careful of what is said around the patient while in a coma.

How Long Will a Coma Last?

There is no reliable way to accurately tell how long a coma will last, and there are currently no medications, which will reliably shorten the duration of a coma. A coma is usually said to last no longer than four weeks [6], however an individual in Post-Coma Unresponsiveness may remain in this state from months to years. Recently, programs that use sensory or physical stimulation to accelerate the healing process and bring someone out of a coma have been used in the United States and claim high levels of success. The Coma Recovery Association, Inc. contains details on their website [7]. Before any program is attempted, it should be discussed with the treating medical team. It is also important to note that a coma may accelerate healing, and attempts to rouse somebody from a coma should not be attempted too soon after the accident.

Coming out of Coma

Unlike the popular concept of coma shown in many movies, an individual coming out of a coma doesn’t just wake up, individuals will go through a gradual process of regaining consciousness - see the coma scale described above. When a patient responds with intentional movement or attempts to communicate, they are generally considered to have emerged from coma. Following emergence from coma individual’s progress to another level of consciousness known as Post Traumatic Amnesia ( PTA). Individuals in PTA are partially or fully awake, but are confused about the day and time, where they are, what is happening and sometimes who they are.

It is also possible for an injury or pressure to the Frontal Lobes to mimic the effects of PTA, so diagnostic scans may be used during PTA to ensure that the diagnosis is correct as well as to ensure that healing is progressing normally.
For more information on PTA see our Post Traumatic Amnesia-Fact Sheet.

Further information

 • Coma Recovery Association http://www.comarecovery.org/
• Glasgow Coma Scale http://www.neuroskills.com/glasgow.shtml
• Rancho Los Amigos Scale http://www.neuroskills.com/rancho.shtml
• Zolpidem http://en.wikipedia.org/wiki/Zolpidem

References

[1] Leon-Carrion, J., del Rosario Dominguez-Morales, M., & Dominguez-Roldan, L.M. (2006). Low-level responsive states. In J. Leon-Carrion, K. R. H. von Wild and G. A. Zitney (Eds.), Brain Injury Treatment: Theories and Practices. New York, NY: Taylor & Francis.