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ASIA International Standards for Neurological Classification of Spinal Cord Injury

Q1. What do the ASIA International Standards for Neurological Classification of Spinal Cord Injury assess?
1. The International Standards for Neurological Classification of SCI categorize motor and sensory impairments in individuals with SCI.
2. They identify sensory and motor levels indicative of the lowest spinal levels demonstrating “unimpaired” function.
Q2. Describe the ASIA International Standards for Neurological Classification of Spinal Cord Injury.
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 (AIS).
Q3. Describe how sensory and motor functions are scored in the ASIA International Standards for Neurological Classification of Spinal Cord Injury.
1. A clinical neurological 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 range of motion (ROM) against significant resistance).
2. The presence of anal sensation and voluntary anal contraction are assessed as a yes or 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.
Q4. This patient has AIS C. What does this mean?
1. AIS C represents an incomplete level of injury where there is sacral sparing and more than half (more than 50%) of the key muscles below the neurologic level of injury have muscle grades of less than 3/5.
Q5. What are the advantages of the ASIA International Standards for Neurological Classification of Spinal Cord Injury?
1. The standards are widely used for research and clinical purposes; ASIA has high face content validity (See table 1 for Psychometric Summary).
2. ASIA motor scores collected early following injury have some predictive validity in explaining functional outcomes.
Q6. What are the disadvantages of the ASIA International Standards for Neurological Classification of Spinal Cord Injury?
1. Inter-rater reliability for assignment of motor and sensory levels and AIS classifications is less than optimal (See table 1 for Psychometric Summary).
Summary – American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury

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 a 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.

Summary

Table 1. ASIA Psychometric 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

For more information, please see: American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury.