The ASIA Impairment Scale (American Spinal Injury Association) is the international standard for classifying spinal cord injury severity. ASIA classification is critical evidence in legal cases because it objectively measures injury severity and guides damage calculations.

Understanding the ASIA Examination

The ASIA examination tests motor function (strength) and sensory function (feeling) at specific points throughout the body:

Motor Testing

Strength is tested in 10 key muscle groups (5 upper body, 5 lower body) on each side:

  • C5—elbow flexors (biceps)
  • C6—wrist extensors
  • C7—elbow extensors (triceps)
  • C8—finger flexors
  • T1—finger abductors
  • L2—hip flexors
  • L3—knee extensors
  • L4—ankle dorsiflexors
  • L5—long toe extensors
  • S1—ankle plantar flexors

Each muscle is scored 0-5, with 5 being normal strength. Total motor score ranges from 0-100.

Sensory Testing

Light touch and pin prick sensation are tested at 28 key points on each side of the body, corresponding to specific nerve roots (dermatomes).

Each point is scored 0-2:

  • 0 = absent
  • 1 = impaired
  • 2 = normal

Total sensory score ranges from 0-224.

Sacral Sparing

Critical to classification is whether any function is preserved in the lowest sacral segments (S4-S5):

  • Sensation at the anal mucocutaneous junction
  • Voluntary anal sphincter contraction

Any sacral sparing indicates an incomplete injury with better prognosis.

The ASIA Impairment Scale

ASIA A: Complete Injury

No motor or sensory function is preserved in sacral segments S4-S5.

  • No voluntary anal contraction
  • No sensation at anal junction
  • Worst prognosis for neurological recovery

ASIA B: Sensory Incomplete

Sensory but not motor function is preserved below the neurological level, including sacral segments.

  • Some sensation below injury level
  • No useful motor function below injury level
  • Better prognosis than ASIA A

ASIA C: Motor Incomplete

Motor function is preserved below the neurological level, and more than half of key muscles below the level have a grade less than 3.

  • Some movement below injury level
  • Most muscles too weak for functional use
  • Significant recovery potential with rehabilitation

ASIA D: Motor Incomplete

Motor function is preserved below the neurological level, and at least half of key muscles below the level have a grade of 3 or greater.

  • Functional strength in many muscles
  • May be able to walk with assistance
  • Best prognosis among incomplete injuries

ASIA E: Normal

Motor and sensory function are normal in all segments. Used when prior deficits have resolved.

Neurological Level of Injury

The neurological level is the most caudal (lowest) segment with normal motor and sensory function on both sides.

This level determines what functions are affected:

  • C4 and above—quadriplegia, possible ventilator dependence
  • C5-C8—quadriplegia with varying arm function
  • T1-T12—paraplegia with full arm function
  • L1 and below—lower extremity weakness, often ambulatory

ASIA Classification in Legal Cases

Objective Severity Measure

ASIA classification provides objective evidence of injury severity:

  • Standardized examination by qualified physician
  • Numerical scores that document function precisely
  • International standard understood by all experts

Prognosis Correlation

ASIA grade correlates strongly with recovery expectations:

  • ASIA A—less than 5% convert to motor function
  • ASIA B—approximately 30% gain some motor function
  • ASIA C—approximately 75% gain functional walking
  • ASIA D—approximately 95% regain functional walking

This data supports damage calculations and life care planning.

Tracking Recovery or Decline

Serial ASIA examinations document:

  • Whether improvement is occurring
  • When recovery has plateaued
  • Any neurological decline requiring investigation

Supporting Expert Testimony

Medical experts use ASIA classification to explain:

  • Injury severity in terms juries understand
  • Expected functional limitations
  • Realistic prognosis for recovery
  • Lifetime care requirements

Ensuring Proper ASIA Documentation

Timing of Examinations

  • Initial exam—within 72 hours once spinal shock resolves
  • Follow-up exams—at regular intervals during rehabilitation
  • Plateau exam—when maximum recovery is reached (typically 1-2 years)

Qualified Examiner

ASIA exams should be performed by physicians trained in the examination technique—typically physiatrists, neurologists, or spinal cord injury specialists.

Complete Documentation

Ensure medical records include:

  • Full motor and sensory examination results
  • ASIA impairment scale grade
  • Neurological level of injury
  • Zone of partial preservation if applicable

Conclusion

The ASIA Impairment Scale provides the standardized, objective measurement of spinal cord injury severity that legal cases require. Proper ASIA classification supports injury severity claims, prognosis opinions, and damage calculations. Ensure your medical records include complete ASIA documentation from qualified examiners.