International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI)
The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) or more commonly referred to as the ASIA Impairment Scale (AIS), was developed by the American Spinal Injury Association (ASIA) as a universal classification tool for Spinal Cord Injury based on a standardized sensory and motor assessment, with the most recent revised edition published in 2011. The impairment scale involves both a motor and sensory examination to determine the sensory and motor levels for the right and left side, the overall neurological level of the injury and completeness of the injury i.e. whether the injury is complete or incomplete. 
Defined as the most caudal, intact dermatome for both pin prick and light touch sensation.
Defined by the lowest key muscle function that has a grade of at least 3 (on supine testing), providing the key muscle functions represented by segments above that level are judged to be intact (graded as a 5).
Neurological Level of InjuryThis refers to the most caudal segment of the cord with intact sensation and antigravity (3 or more) muscle function strength, provided that there is normal (intact) sensory and motor function rostrally respectively.
A = Complete. No sensory or motor function is preserved in the sacral segments S4-S5.
B = Sensory Incomplete. Sensory but not motor function is preserved below the neurological level and includes the sacral segments S4-S5, AND no motor function is preserved more than three levels below the motor level on either side of the body.
C = Motor Incomplete. Motor function is preserved below the neurological level, and more than half of key muscle functions below the single neurological level of injury have a muscle grade less than 3 (Grades 0-2).
D = Motor Incomplete. Motor function is preserved below the neurological level, and at least half (half or more) of key muscle functions below the NLI have a muscle grade ≥ 3.
E = Normal. If sensation and motor function as tested with the ISNCSCI are graded as normal in all segments, and the patient had prior deficits, then the AIS grade is E. Someone without a SCI does not receive an AIS grade.
A key point in each of the 28 dermatomes (from C2-S4-5) is tested bilaterally using light touch and pin-prick (sharp-dull discrimination). Equipment common to clinical settings, such as a cotton wisp and safety pin, may be used. Appreciation of sensation is tested in comparison to sensation on the patient’s cheek. A three-point scale is used for scoring:
0 = absent
1 = altered (impaired or partial appreciation, including hyperesthesia)
2 = normal or intact (similar as on the cheek)
NT = not testable
Deep anal pressure (formerly deep anal sensation): A gentle pressure is applied to the anorectal wall by the examiner’s fnger. Perceived pressure is graded as absent or present.
Key muscle functions of the myotomes C5-T1 and L2-S1 are tested bilaterally. A six-point scale is used for scoring:
0 = total paralysis
1 = palpable or visible contraction
2 = active movement, full range of motion (ROM) with gravity eliminated
3 = active movement, full ROM against gravity
4 = active movement, full ROM against gravity and moderate resistance in a muscle specific position
5 = (normal) active movement, full ROM against gravity and full resistance in a muscle specific position expected from an otherwise unimpaired person
5* = (normal) active movement, full ROM against gravity and sufficient resistance to be considered normal if identified inhibiting factors (i.e., pain, disuse) were not present
NT = not testable (i.e., due to immobilization, severe pain such that the patient cannot be graded, amputation of limb, or contracture of >50% of the range of motion)
Voluntary anal contraction: The patient is asked to voluntarily contract the external anal sphincter around the examiner’s finger. The contraction is scored as absent or present.
Determination of Neurological Level of Injury
The neurological level of injury is determined by identifying the most caudal segment of the cord with both intact sensation and normal antigravity muscle function strength. The sensory level refers to the most caudal, intact dermatome for both light touch and pin-prick sensation (score=2). The motor level refers to the most caudal myotome with a key muscle function of at least grade 3. If there is a discrepancy between the most caudal intact section between the four possible levels of right sensory level, left sensory level, right motor level, or left motor level, the neurological level of injury is considered the most rostral segment of these four levels.
Zone of Partial Preservation
In complete injuries (AIS A), the zone of partial preservation refers to dermatomes and myotomes caudal to the sensory or motor level that remains partially innervated.
The ISNCSCI measures neurological status in order to describe a patient’s level of impairment. Functional tests are not included in the ISNCSCI examination. However, functional outcomes are necessary for understanding the functional consequences of the level of impairment .
Functional tests that the clinician may consider include:
- 6-minute walk test (6MWT)
- 10-meter walk test (10MWT)
- Berg Balance Scale
- Walking index for spinal cord injury (WISCI II)
- Spinal cord injury functional ambulation inventory (SCI-FAI)
- Timed Up and Go Test (TUG)
- Graded redefined assessment of strength sensibility and prehension (GRASSP)
- Modified functional reach test (mFRT)
- Spinal cord independence measure, version III (SCIM-III)
- Quadriplegia index of function (QIF)
The ISNCSCI sensory and motor examinations are reliable when conducted by a trained examiner. Formal training in the administration of the ISNCSCI standards has been shown to improve the accuracy of the examiner’s classification.
The ISNCSCI are validated for injury classification.
Construct validity of the ASIA motor score as a measure of recovery following SCI and as an outcome measure for clinical trials is greater when upper and lower extremity motor scales are scored independently and not summated together.
- To promote the teaching and competent use of the Standards, ASIA with contribution from the International Spinal Cord Society has developed the International Standards Training e-Learning Program or InSTeP.
- The goal of this training for the Autonomic Standards is to learn normal autonomic functions, understand the changes in autonomic functions following spinal cord injury (SCI) and use the Autonomic Assessment to document and classify remaining autonomic neurological function.
- Burns S, Biering-Sørensen F, Donovan W, Graves D, Jha A, Johansen M, Jones L, Krassioukov A, Kirshblum, Mulcahey MJ, Schmidt Read M, Waring W. International Standards for Neurological Classification of Spinal Cord Injury, Revised 2011. Top Spinal Cord Inj Rehabil 2012;18(1):85-99.
- Kaplan M. Kaplan - ASIA assessment. Available from: http://www.youtube.com/watch?v=IP_wunjn9Io [last accessed 13 October 2013]
- Kalsi-Ryan S, Wilson J, Yang JM, Fehlings MG. Neurological grading in traumatic spinal cord injury. World Neurosurg 2013. http://dx.doi.org/10.1016/j.wneu.2013.01.007 (accessed 13 October 2013).
- Marino R, Jones L, Kirshblum S, Tal J, Dasgupta A. Reliability and repeatability of the motor and sensory examination of the international standards for neurological classification of spinal cord injury. J Spinal Cord Med 2008;31(2)166-170.
- Schuld C, Wiese J, Franz S, Putz C, Stierle I, Smoor I, Weidner N, EMSCI Study Group, Rupp RR. Effect of formal training in scaling, scoring and classification of the international standards for neurological classification of spinal cord injury. Spinal Cord 2013;51(4):282-8.
- Graves D, Frankiewicz RG, Donovan WH. Construct validity and dimensional structure of the ASIA motor scale. J Spinal Cord Med 2006;29(1):39-45.