American Spinal Injury Association Score (ASIA Impairment Scale) has now been renamed as the International Standards for Classification of Spinal Cord Injury Motor Score (ISNCSCI).
It is used to describe neurological function after spinal injury, and is determined by going through the following steps:
- Sensory examination (see chart)
- Motor examination
- Determining level of both sensory and motor impairment
- Assessing whether the injury is complete
The finding are then used to determine a grade A-E, please see below.
The sensory score is determined using this scale for as many as 28 key points (corresponding to dermatomes, please see the chart below):
0 – The sensation is absent
1 – The sensation is present but impaired
2 – The sensation is normal
NT – not testable.
For the motor examination 10 key muscles, 5 in the upper limb and 5 in the lower limb are tested. Five specific upper extremity muscles, one from each respective segment of the cervical cord, are scored on a 5-point muscle grading scale. Five specific lower extremity muscles are similarly scored.
Muscle strength is graded as
0 – Total paralysis
1 – Palpable or visible contraction
2 – Active movement, full range of motion, gravity eliminated
3 – Active movement, full range of motion, against gravity
4 – Active movement, full range of motion, against gravity and provides some resistance
5 – Active movement, full range of motion, against gravity and provides normal resistance [Muscle able to exert, in examiner’s judgement, sufficient resistance to be considered normal if identifiable inhibiting factors were not present]
NT – not testable. Patient unable to reliably exert effort or muscle unavailable for testing due to factors such as immobilization, pain on effort or contracture.
The sum of all 20 muscle yields a total motor score for each patient, with a maximum possible score of 100 points for patients with no weakness. A different score, however for upper limbs and lower limbs can be calculated making it 50 maximum for both upper and lower limb.
Voluntary anal contraction is also noted.
Source: American Spinal Injury Association