What is sacral sparing and why does it matter?

Sacral sparing refers to preserved sensory or motor function in the sacral segments S4–S5, including light touch or pin-prick at the perianal area, deep anal pressure, or voluntary anal sphincter contraction. Its presence means the spinal cord is not completely severed and upgrades the injury from AIS A to at least AIS B, which carries a meaningfully better prognosis.

What is the neurological level of injury (NLI)?

The NLI is the most caudal (lowest) spinal segment with intact sensory and motor function bilaterally. Motor level is the lowest key muscle that grades at least 3/5 with the segment above grading 5/5. Sensory level is the lowest dermatome with normal light touch and pin-prick on both sides. The NLI is the higher (more caudal) of the four values.

How do AIS C and AIS D differ?

Both grades require sacral sparing and voluntary anal contraction (or motor function more than three levels below the motor level). AIS C means fewer than half of the key muscles below the NLI grade 3 or higher. AIS D means at least half of those muscles grade 3 or higher. AIS D patients generally have a better functional prognosis than AIS C.

Does this tool replace the ISNCSCI worksheet?

No. The International Standards for Neurological Classification of SCI (ISNCSCI) worksheet scores all 28 dermatomes and 10 key muscle groups and is required for complete, research-grade classification. This tool guides the high-level AIS grade decision based on the critical branch points — sacral sparing and the motor-function threshold — without replacing a full scored exam.

Is patient data stored or transmitted?

No. All logic runs entirely in your browser. Nothing is sent to any server and nothing is stored after you close the page.

Spinal Cord ASIA Impairment Scale

Name: Spinal Cord ASIA Impairment Scale
Availability: InStock
Author: Nham Vu

Enter motor and sensory exam findings to determine the ASIA Impairment Scale grade and neurological level of injury.

Exam Findings

1. Sacral Sparing (S4–S5)

Any of: light touch or pin-prick at perianal area, deep anal pressure, OR voluntary anal contraction.

Present Absent

AIS Grade Reference

Grade	Type	Definition
A	Complete	No sensory or motor function in S4–S5
B	Sensory Incomplete	Sensory but no motor below NLI, including S4–S5
C	Motor Incomplete	Motor below NLI present; <50% of key muscles grade 3+
D	Motor Incomplete	Motor below NLI present; ≥50% of key muscles grade 3+
E	Normal	Normal sensory and motor function (prior SCI diagnosis required)

Complete the exam findings on the left and click Classify Injury to see the AIS grade.

Summary

Enter motor and sensory exam findings to determine the ASIA Impairment Scale grade and neurological level of injury.

How it works

Assess sacral sparing: test light touch and pin-prick at S4–S5 and check for voluntary anal contraction.
If no sacral sparing is present, the injury is AIS A (complete).
If sacral sparing is present, determine whether any motor function exists more than three levels below the motor level on each side.
If motor function is absent below three levels, grade as AIS B (sensory incomplete).
If motor function is present below three levels but the majority of key muscles grade less than 3/5, classify as AIS C.
If the majority of key muscles grade 3 or higher below the neurological level, classify as AIS D.
AIS E is assigned when motor and sensory function are normal but a prior SCI diagnosis exists.

Use cases

Classify acute SCI severity in the emergency or intensive care setting.
Track neurological recovery over serial exams during rehabilitation.
Communicate injury level and completeness consistently across care teams.
Document SCI classification in clinical records and research databases.
Teach residents and students the AIS grading framework.
Support prognosis discussions with patients and families.

Frequently Asked Questions

Last updated: 2026-07-24 · Reviewed by Nham Vu