What is the ASIA Impairment Scale and How is it Used?

The ASIA Impairment Scale looks at motor and sensory function in an individual and how it has been impacted following a spinal cord injury.

Defining how a patient is affected can be used to better understand the injury they have sustained and help deliver the rehabilitation and support that will enable them to live their lives more fully.

The effective diagnosis of any spinal cord injury is vital. Not only does this help dictate what treatment is provided at the acute stage of the injury but it can also be used to assist the individual cope with their condition as they return home and begin rehabilitation.

In simple terms, an individual will be classed on the basis of where their injury occurs and whether it is incomplete or complete. The initial treatment of the acute phase is focused on preventing any further damage whilst also providing the necessary medical support to improve the prognosis of the patient.

The rehabilitation phase of recovery, however, also requires a much deeper understanding of the extent of an injury as this will be used to determine what help the individual will need.

Having a clear idea of the effect of a particular injury is important in deciding where rehabilitation techniques should focus on, what the prognosis is likely to be and what support the individual will need.

Defining spinal cord injuries has developed considerably since the 1970s when the first diagnostic tool was introduced, particularly with the development of the ASIA Impairment Scale. This comprehensive assessment is used to define sensory and motor function in an individual with a spinal cord injury.

Here we take a closer look at what how the ASIA Impairment Scale helps assess individuals and how it is used to provide the appropriate rehabilitation and support. 

What is the ASIA Impairment Scale?

The ASIA (American Spinal Injury Association) Impairment Scale is used to describe an individual’s functional impairment that has occurred as a result of sustaining a spinal injury. It looks at a five-level scale to determine both sensory and motor function below the area of the injury.

An example of the checklist used by a medical professional when assessing a patient within the ASIA Impairment Scale guidelines can be viewed here.

Testing is fairly simple. For example, sensory impairment is tested through light touch and pin-prick methods and scored in comparison to sensation on the cheek area. The examination is carried out over 28 key sensory points both on the right and left side of the individual.

It is defined on a scale of 0 to 2:

• 0: Sensation is completely absent
• 1: Sensation is altered or impaired, including hypersensitivity
• 2: Sensation is normal

Motor function testing is far more complicated and difficult to gauge, but diagnosing as clearly as possible is important for the rehabilitation process.

Normally, muscle function is scored on a scale from 0 to 5 for each of the areas investigated and a compiled score is obtained to define overall mobility.

• 0: There is total paralysis
• 1: There is palpable or visible contraction of the muscle.
• 2: There is active movement with full range of motion with gravity eliminated.
• 3: There is active movement, with full range of motion against gravity.
• 4: There is active movement, full range of motion against gravity and moderate resistance in a muscle-specific position.
• 5: There is normal active movement.

Some cases are defined as ‘not testable’ and this could happen for a variety of reasons. For example, the patient may be in too much pain to contract a particular muscle or won’t be able to assess the amount of sensation.  

How to Use the ASIA Impairment Scale

The five different grades on the ASIA Impairment Scale are designed to give rehabilitation professionals a full understanding of their patient’s condition.

• Grade A: This is the most severe level, as the injury is considered complete. That means there is no sensory or motor function below the level of the injury.
• Grade B: The impairment to function is incomplete on this scale and everything below. There is sensory function but no motor function below the damaged area. This will also include some sensory function in the sacral area of the spine at S4 and S5.
• Grade C: The injury is incomplete but there is observable motor function. More than half of muscles, however, are weakened and are not able to move against gravity.
• Grade D: There is more motor function available, with more than half of the patient’s muscles being able to move against gravity.
• Grade E: This is the best outcome and the individual has a full range of motor and sensory function.

The key here is to define the individuals condition and how their spinal cord injury is likely to affect them in the future. It allows the rehabilitation team to put in place functional goals depending on the level of the patient’s spinal cord injury and the severity of their condition.