A disorder of consciousness, or impaired conciousness, is a state where consciousness is affected by an injury to the brain.
Consciousness refers to both wakefulness and awareness. Wakefulness is the ability to open your eyes and have basic reflexes such as coughing, swallowing and sucking.
Awareness is associated with more complex thoughts and actions, such as following instructions, remembering, planning and communicating.
There are several different states of impaired consciousness, depending on how these abilities are affected. These include:
coma – when there are no signs of wakefulness or awareness
vegetative state – when a person is awake but showing no signs of awareness
minimally conscious state – when there is clear but minimal evidence of awareness that comes and goes
Note that people with locked-in syndrome are conscious and aware, but completely paralysed and only able to control eye movement.
Why they happen
Disorders of consciousness can occur if the parts of the brain involved with consciousness are damaged. These types of brain injury can be divided into:
traumatic brain injury – the result of a severe head injury, such as an injury sustained during a car accident or a fall from a great height
non-traumatic brain injury – where the injury to the brain is caused by a health condition such as a stroke
progressive brain damage – where the brain is gradually damaged over time, for example because of Alzheimer's disease
Making a diagnosis
A disorder of consciousness will only be confirmed after extensive testing to determine levels of wakefulness and awareness.
These examinations need to be carried out by someone experienced in disorders of consciousness, although the views of other healthcare professionals and family members will also be taken into consideration.
For some states of impaired consciousness, such as vegetative state, there are recommended criteria to help confirm a diagnosis.
Treatment and care
Treatment can't ensure recovery from a state of impaired consciousness. Instead, supportive treatment is used to give the best chance of natural improvement. This can involve:
making sure the person is regularly moved so they don't develop pressure ulcers
gently exercising their joints to prevent these from becoming tight
In some cases, a treatment called sensory stimulation may be used in an attempt to increase responsiveness. This involves stimulating the main senses, such as vision, hearing and smell. For example, a person's favourite song may be played to stimulate their hearing. However, it's not entirely certain how effective this treatment is.
If health professionals and family members agree there is no point in continuing treatment, the decision usually has to be referred to the courts before treatment can be withdrawn.
This would usually be considered if a person was in a state of impaired consciousness for at least 12 months, as by this point the chances of recovery are remote.
It's impossible to predict the chances of someone in a state of impaired consciousness improving. It largely depends on the severity and type of brain injury, the person's age and how long they've been in a state of impaired consciousness for.
Some people improve gradually, whereas others stay in a state of impaired consciousness for years. Many people never recover consciousness.
There are only isolated cases of people recovering consciousness after several years. The few people who do regain consciousness often have severe disabilities caused by the damage to their brain.
Information for anyone whose friend or loved one is in a coma