Coma
A person in a coma is unconscious and has minimal brain activity. They are alive but cannot be woken up and show no signs of being aware. Their eyes will be closed and they will appear to be unresponsive to their environment. They will not normally respond to sound or pain or be able to communicate or move voluntarily.
Their basic reflexes such as coughing and swallowing will be reduced. They may be able to breathe on their own, although some people require a machine to help with this.
Over time, they may gradually start to regain consciousness and become more aware. A coma usually lasts for less than two to four weeks, during which time those affected may wake up or may progress into a vegetative state or a minimally conscious state.
Vegetative State
In a vegetative state a person is unconscious. They have transitioned from being in a coma and will have sleep wake cycles but have no awareness of themselves or their environment.
The main difference between a coma and a vegetative state is that in a vegetative state, at some point, a person’s eyes will be open and there will be times when they appear to be awake. They may move parts of their body, but this movement is not voluntary. Movements can include grinding of teeth, thrashing and facial movements, for example grimacing, yawning or smiling. They might jerk as a reflex response to a loud noise or move a hand away from a source of pain. They may produce sounds such as grunting or moaning or even occasional words.
After four weeks, a person is said to be in a prolonged vegetative state. If they remain in a vegetative state for several months after brain damage involving oxygen-deprivation (caused, for example, by a cardiac arrest), or for one year after a traumatic brain injury (such as a car accident, a fall or an assault), the chances of recovering consciousness are very low and they are said to be in a permanent vegetative state.
Minimally Conscious State
A person who shows clear but minimal or inconsistent awareness is classified as being in a minimally conscious state. They will show some evidence of awareness of themselves or their environment. They may enter this state after being in a coma or vegetative state. In some cases it is a stage on the route to recovery but in others it's permanent.
It is sometimes referred to as a low awareness state. A person who is vegetative might grasp a loved one’s hand reflexively but a person who is minimally conscious could reach for the hand of someone they love.
Their consciousness is however likely to fluctuate, there will therefore be times when they can do things and times when they cannot.
As with vegetative state, a continuing minimally conscious state means it has lasted for longer than four weeks. It is more difficult to diagnose a permanent minimally conscious state because it depends on:
- the type of brain injury
- how severe the injury is
- how responsive the person is
In most cases, a minimally conscious state isn't usually considered to be permanent until it has lasted several years.