Table of Contents
S4-5: Perianal area <1 cm lateral to the mucocutaneous junction (taken as one level)
1. Sensory (-) and Motor (-): AIS A (Complete)
i.e. N-0-0-0-0-N sign (No sacral sparing)
2. Sensory (+) and Motor (-): AIS B
i.e. Sensory (+) means any sensation present in S4/S5 or anal sensation
Motor (-) means no Voluntary Anal Contraction
3. Sensory (+) and Motor (+): AIS C or D
Check Motor Function
- Motor 0/5, >3 levels below motor level: AIS B
- Motor 1/5 or 2/5 in atleast 1/2 of key muscles below NLI (Neurologic Level of Injury): AIS C
- Motor 3/5 or more in atleast 1/2 of key muscles below NLI: AIS D
Sensory and Motor Normal in All Segments
- Prior deficits: AIS E
- No prior deficits: Cannot be graded
1. Sensory level: Lowest dermatome with both sensation 2/2 and all segments above being 2/2.
2. Motor level: Lowest myotome with motor 3/5 or more with all myotome above being 5/5.
3. Sensory level where motor level cannot be tested (C2-4, T2-L1, S3-5): Motor level is considered the same as sensory level.
4. Neurologic Level of Injury (NLI): Sensory and motor level may be different for right and left producing 4 possible levels (right sensory, left sensory, right motor, left motor). NLI is the highest level among these 4.
5. Zone of Partial Preservation (ZPP) irrespective of AIS grade: Lowest dermatome or myotome on each side with some preservation. It is used only in injuries with absent motor or sensory function in S4-S5.
6. Motor score: 10 key muscle groups tested in SUPINE position and scored 0 to 5 or NT (not tested).
- Max. score for each limb = 5 X 5 = 25 (Maximum = 25 X 4 = 100)
7. Sensory score: 28 dermatomes tested for Light touch/LT (posterior column – use cotton tip applicator) and Pin Prick/PP (spinothalamic tract – use safety pin) and scored 0 to 2 or NT (not tested).
- Max. score for PP or LT on each side = 2 X 28 = 56 (Maximum = 56 X 4 = 224)
8. When to test non-key muscles?
In a patient with an apparent AIS B classification, non-key muscle functions
more than 3 levels below the motor level on each side should be tested to
most accurately classify the injury (differentiate between AIS B and C).
Further reading of cases and examples of ASIA grading:
ASIA 2019 revision
ASIA-ISCOS 2019 Worksheet