Classification of severity of brain injury

There are a plethora of assessment scales for determining the severity of brain injury and resulting disability. With the exception of the Glasgow Coma Score, different hospitals tend to use different scales. Some of the most commonly used are discussed below.

The severity of brain injury at initial presentation in the Accident and Emergency Department is assessed by the Glasgow Coma Score (See the link at the bottom of the page). The score is from 15 for fully alert to 3 for the deepest coma. However, there is a poor correlation between the Glasgow coma scale and outcome.

Another common measure of the severity of brain injury is the duration of post-traumatic amnesia (PTA). PTA is defined as the interval between injury and when the person regains continuous ongoing memory.

There is a good correlation between the duration of PTA and the outcome grade at 6 months. In a study of PTA and outcome, no one with a PTA of less than 2 weeks was severely disabled, whilst a quarter of those with a PTA of more than 4 weeks made a good recovery.

There is also a crude correlation between the amount of brain damage on MRI scan and the long-term outlook.

Please see the link at the bottom of the page for other methods of determining severity of brain injury.

Classification of outcome

The most widely used measure of outcome after head injury is the Glasgow Outcome Scale.

Good recovery indicates either resumption of normal activities or the capability of doing so. These people may have minor cognitive deficits or personality change.

Moderate disability indicates that the person has deficits, either physical or cognitive, but that these deficits do not prevent the person from being independent (capable of living alone and using public transport).

Severe disability is defined as occurring when a person is dependent upon someone else for at least some activities in each 24 hours. This covers a wide range of dependency from requiring someone for help with toileting, feeding and dressing to needing help only in organising daily activities when impaired by cognitive and behavioural problems. These may make it impractical for such a person to live alone.

Vegetative survival indicates a person who is awake and demonstrates periods of eye opening but who is not aware and shows no psychologically meaningful responses to external stimuli and no speech. Such people require continuous nursing care.

Click on the links for details of:

• The Glasgow coma score
• Other methods of assessing brain injury