This 2017 'Classifications In Brief' review describes the ASIA Impairment Scale (AIS) — the international standard for classifying spinal cord injuries. It covers the scale's origins (replacing the Frankel scale in 1982), the three-part standardized examination, grading criteria for Grades A–E, reliability data, and prognostic performance. The paper also addresses the AIS's known limitations, including the absence of a minimal clinically important difference.
When you evaluate a patient after acute spinal cord injury, the most important early task is determining complete versus incomplete status — but that determination is only valid after spinal shock has resolved. Return of the bulbocavernosus reflex is your signal that the examination is now meaningful. Classifying before that point risks falsely labeling a recoverable injury as complete.
Grade A is not just a category. It is a prognosis. A confirmed Grade A injury means a 91.7% chance the patient will not walk independently at 1 year, and only a 2.1% chance of ever converting to incomplete status. Grade D is the mirror image: 97.3% of these patients regain independent ambulation. These numbers are what you use when a family asks "will he walk again?"
The AIS replaced the Frankel scale because Frankel failed to specify injury level and left 'motor useful' vs 'motor useless' undefined. Subjective and unreproducible. The AIS fixed both problems, and its reproducibility (correlation coefficients ≥0.90 for motor and sensory) is why it became the required outcome measure for virtually every SCI clinical trial. One critical caveat: always report grade with level. A Grade A injury at L3 and one at C4 are not the same injury. The AIS was never designed to be used without the neurologic level.
This 2017 'Classifications In Brief' review describes the ASIA Impairment Scale (AIS) — the international standard for classifying spinal cord injuries. It covers the scale's origins (replacing the Frankel scale in 1982), the three-part standardized examination, grading criteria for Grades A–E, reliability data, and prognostic performance. The paper also addresses the AIS's known limitations, including the absence of a minimal clinically important difference.
When you evaluate a patient after acute spinal cord injury, the most important early task is determining complete versus incomplete status — but that determination is only valid after spinal shock has resolved. Return of the bulbocavernosus reflex is your signal that the examination is now meaningful. Classifying before that point risks falsely labeling a recoverable injury as complete.
Grade A is not just a category. It is a prognosis. A confirmed Grade A injury means a 91.7% chance the patient will not walk independently at 1 year, and only a 2.1% chance of ever converting to incomplete status. Grade D is the mirror image: 97.3% of these patients regain independent ambulation. These numbers are what you use when a family asks "will he walk again?"
The AIS replaced the Frankel scale because Frankel failed to specify injury level and left 'motor useful' vs 'motor useless' undefined. Subjective and unreproducible. The AIS fixed both problems, and its reproducibility (correlation coefficients ≥0.90 for motor and sensory) is why it became the required outcome measure for virtually every SCI clinical trial. One critical caveat: always report grade with level. A Grade A injury at L3 and one at C4 are not the same injury. The AIS was never designed to be used without the neurologic level.