Motor Level

Level of the caudal innervated muscle having grade 3 or better strength where all muscles above are graded 5.

Sensory Level

Caudal dermatomal level with normal sensation to pinprick and light touch with all dermatomes above being normal.

Neurological Level

Rostral of either the sensory or motor levels

When there is no key muscle immediately rostral to a key muscle graded 3 or 4, use the sensory exam as indicatve of motor function at that more rostral level

If the level of injury is at a site for which there is no key muscle (e.g. C2-C4, T2-L1, S2-S4/5), the motor level is defined by the sensory level.

AIS Classification
A Complete.
No sensory or motor function at S4/S5
B Sensory Incomplete.
Sensory, but no motor function at S4/S5
C Motor Incomplete.
1) Voluntary anal contraction present or
2) Motor function present more than 3 myotomes below motor level
3) The myotome tested does not have to be a key muscle group, just 4 or more levels below the motor level
D Motor Incomplete.
Half or more key muscles below the single neurological level have a grade greater than or equal to 3.
E Normal.
All components of International Standards Exam are Normal.
ISNCSCI 2019 Revisions - The ‘*’ Concept

Before, “5*” was used when full muscle strength could not be achieved due to what the examiner believes to be a non-SCI condition. Now, a general ‘*’-concept is introduced, where all abnormal exam scores can be tagged with a ‘*’ to indicate a non-SCI condition impacts exam results. This general ‘*’-concept is applicable to motor scores of 0-4 and NT as well as to sensory scores of 0, 1 or NT, independent from the level of occurrence (above, at or below the sensory/motor level).

While ‘*’-tagged scores above the sensory/motor level will in most cases be handled as normal during classification, ‘*’-tagged scores at or below the motor/sensory level indicating a non-SCI related impairment superimposed to deficits caused by SCI will typically be handled as not normal.

With this new non-SCI taxonomy, motor and sensory sum scores are always calculated on the basis of the examined scores. As in the past, if key muscles or dermatomes cannot be tested (‘NT’), the sum score is not defined, and should be noted as ‘ND’.

ISNCSCI 2019 Revisions - Zone of Partial Preservation

Before, ZPPs were only defined for complete (AIS A) injuries with no sensorimotor function in the most caudal sacral segments.

Motor ZPPs should now be documented in incomplete injuries with absent VAC. Sensory ZPP on each side (L/R) is now defined in the absence of sensory function in S4-5 (LT, PP) on that side as long as DAP is not present. This means that in cases with present DAP, sensory ZPPs on both sides are not defined and should be noted as “not applicable (N/A)”. In cases with absent DAP, a sensory ZPP can be defined on one side (e.g., L) , while it may not necessarily be applicable on the other side (e.g., R).

In complete (AIS A) injuries, the new ZPP definition is still fully compatible with the former definition and does not lead to different classification results

Generally, non-key muscles are not used for the definition of the motor ZPP with one exception: if preserved function of a non-key muscle more than 3 segments below the motor level leads to an AIS C grade of an otherwise AIS B graded subject without VAC, the innervation of this non-key muscle determines the motor ZPP on this side.

  • References

    American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury, revised 2019; Richmond, VA.