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ASIA Impairment Scale (AIS)

What does the ASIA Impairment Scale test?
1.The International Standards for Neurological Classification of SCI (ASIA 2002) categorizes motor and sensory impairment in individuals with SCI. It identifies sensory and motor levels indicative of the lowest spinal levels demonstrating “unimpaired” function.
Describe the ASIA Impairment Scale.
1. 28 dermatomes are assessed bilaterally using pinprick and light touch sensation and 10 key muscles are assessed bilaterally with manual muscle testing.
2.The results are summed to produce overall sensory and motor scores and are used in combination with evaluation of anal sensory and motor function as a basis for the determination of the ASIA Impairment Scale.
Describe the numerical grading system of the AIS.
1. A clinical examination is conducted to test whether sensation is 0=”absent”, 1=”impaired” or 2=”normal”. Muscle function is rated from 0=”total paralysis” to 5=”(normal), i.e. active movement, full ROM against significant resistance”.
2. The presence of anal sensation and voluntary anal contraction are assessed as a yes/no.
3. Bilateral motor and sensory levels and the AIS are based on the results of these examinations.
4. A more accurate representation of motor function has been demonstrated when overall ASIA motor scores are divided into separate upper and lower limb scores.
What are the advantages of the AIS?
1. Widely used for research and clinical purposes AIS has high content validity (See table 1). In addition, AIS motor scores collected early following injury have some predictive validity in explaining functional outcomes.
What are the disadvantages of the AIS?
1. Inter-rater reliability for assignment of motor and sensory levels and AIS classifications is less than optimal (See table 1).
Summary – American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury (ASIA) Impairment Scale
Interpretability

The AIS scores are clearly defined and understood by most clinicians. The AIS (5 point ordinal scale), classifies individuals from “A” (complete SCI) to “E” (normal sensory and motor function). Preservation of function in the sacral segments (S4-S5) is key for determining the AIS.

Acceptability – The assessment is generally well tolerated although sensory testing can be problem with severe hypersensitivity and testing for voluntary anal contraction can result in the stimulation of a bowel movement.

Feasibility – Takes approximately 20 minutes to conduct/score. Training is mandatory and no specialized equipment is required. For a copy see ISNCSCI (ASIA) Classification Worksheet.

 

Table 1: ASIA Summary.

Reliability

Validity

Responsiveness

Rigor

Results

Rigor

Results

Rigor

Results

Floor/ceiling

+++

TR ++

++

Construct +++

N/A

N/A

N/A

Note: +++ = Excellent; ++ = Adequate; + = Poor; N/A=Insufficient information; TR=Test re-test