What is the ASIA (American Spinal Injury Association) grade in a patient with a spinal cord injury at or above the T6 level?

ASIA Grading System in Spinal Cord Injury

The ASIA (American Spinal Injury Association) grading system, formally known as the International Standards for Neurological Classification of Spinal Cord Injury, is a standardized classification system that assigns grades from A (complete injury with no motor or sensory function preserved in sacral segments S4-S5) through E (normal sensory and motor function), with B, C, and D representing varying degrees of incomplete injury. 1, 2

Core ASIA Impairment Scale Grades

The ASIA system provides five distinct grades of injury severity 1, 2:

• ASIA A (Complete): No motor or sensory function preserved in the sacral segments S4-S5 1, 2
• ASIA B (Sensory Incomplete): Sensory but not motor function preserved below the neurological level, including sacral segments S4-S5 1, 2
• ASIA C (Motor Incomplete): Motor function preserved below the neurological level, with more than half of key muscle groups below the neurological level having a muscle grade less than 3/5 1
• ASIA D (Motor Incomplete): Motor function preserved below the neurological level, with at least half of key muscle groups below the neurological level having a muscle grade of 3/5 or greater 1
• ASIA E (Normal): Normal sensory and motor function 1, 2

Key Advantages of the ASIA System

The ASIA system provides more accurate definition of complete SCI and improved methods for determining motor and sensory scores compared to older classification systems like the Frankel scale. 1

• The system generates continuous numerical scores for both motor and sensory function, allowing assessment of small increments in recovery that may not change the overall grade 1
• Motor scores are calculated by testing key muscle groups bilaterally using a 0-5 grading scale, with a maximum total motor score of 100 points 1, 3
• Sensory scores assess both light touch and pinprick sensation across dermatomes, providing detailed mapping of preserved function 1, 4

Critical Limitations and Pitfalls

A major disadvantage of the ASIA system is the ceiling effect in Grades C and D, where patients may experience significant functional recovery without changing to the next grade. 1

Timing of Assessment

• At 24-48 hours after injury, ASIA Grade A patients can be predicted with approximately 97.4% accuracy if examiners follow specific rules, including exclusion of all patients with cognitive deficits 1
• ASIA Grades B through D show greater instability in the acute phase, with approximately 60% of patients moving to a higher grade during recovery 1
• One week after trauma is the earliest reliable time for accurate prognostic assessment 1

Common Sources of Error

Inaccurate initial examination can result from 1:

• Patient factors: Inebriation, illicit drugs, cognitive impairment from head injury, hysteria, anxiety, malingering, language incompatibility, or developmental challenges
• Systemic factors: Neurogenic or systemic shock affecting the examination
• Examiner factors: Inexperience or lack of proper training leading to poor interrater reliability

Clinical Application for T6 and Above Injuries

For injuries at or above T6, the ASIA grade determines both neurological severity and risk of autonomic complications, particularly autonomic dysreflexia. 1, 5

• Entry ASIA Impairment Scale grade is the strongest predictor of functional outcomes and should guide treatment planning 1, 5
• Sacral sensation preservation is a critical prognostic indicator that must be specifically documented 1, 5
• Voluntary external anal/urethral sphincter contraction correlates significantly with bladder function recovery and should be assessed 1, 5

Essential Examination Components

Trained examiners must perform standardized assessments to achieve high interrater reliability, with principal investigators never serving as neurological examiners to minimize bias. 1

The examination must include 5, 4:

• Motor strength testing in all major muscle groups bilaterally using the 0-5 scale
• Sensory testing for both light touch and pinprick across all dermatomes
• Sacral examination including perianal sensation, rectal tone, and voluntary anal sphincter contraction
• Documentation of the most caudal segment with motor function rated at ≥3/5 to define the injury level 2

Functional Outcome Integration

While the ASIA system excels at neurological classification, functional outcome measures such as the Functional Independence Measure (FIM), Spinal Cord Injury Measure, and Walking Index in Spinal Cord Injury should be incorporated to assess clinically meaningful recovery. 1

These functional measures address patient-prioritized outcomes including bowel, bladder, sexual function, and ambulation that may not be fully captured by ASIA grades alone 1.