The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) published by ASIA and continuously maintained by the International Standards Committee of ASIA and the International Spinal Cord Society (ISCoS) represents the gold standard assessment for documentation of the level and severity of a spinal cord injury (SCI). Since its first introduction, the ISNCSCI has undergone several revisions with its newest eighth edition released at this year’s ASIA annual meeting in Honolulu. This 2019 revision is based not only upon comments, questions, and suggestions from the international SCI community, clinicians and researchers, but also takes recently available evidence and structured feedback from ISNCSCI training courses into account. The following changes have been introduced:
- A new taxonomy for documentation of non-SCI related impairments is introduced. Based on the feedback from clinicians, there is an increasing (although still low) number of patients with pre-existing or concomitant musculoskeletal, neurological or other problems which have an impact on the ISNCSCI examination results. Such problems include chronic peripheral nerve injuries, fractures, burns, acute or chronic pain or age-related muscle weaknesses. In a previous ISNCSCI revision, the “5*” was foreseen for cases, where the full muscle strength is not achieved, but the examiner thinks that it would be achieved if the non-SCI condition was not present. However, this approach has the drawback that 1) it has been reserved for the motor examination only and 2) the actual examination score is lost unless the examiner explicitly documents it in the comments box. To overcome this limitation a general ‘*’-concept has been introduced, where abnormal examination scores can be tagged with a ‘*’ to indicate that a non-SCI condition impacts the examination results. This general ‘*’-concept is applicable to the motor as well as the sensory exam independent from the level of occurrence (above, at or below the sensory/motor level). The use of the “5*” is not recommended anymore, instead the actual (not normal) examination score should be documented and be tagged with the ‘*’. As such for motor strength, the ‘*’ can be applied to motor scores of 0-4 and for NT, and this can be applied to sensory scores of 0, 1 or NT. Ongoing clinical studies, where the “5*” is currently being used, can continue to use it. However, as outlined in a recent joint publication of ASIA’s International Standards and Educational Committees it is recommended to report on the ISNCSCI revision used in the study in publications.
If an examiner tags a score with the ‘*’, details on the reason for this and how this ‘*’-tagged score should be handled during the classification process need to be specified in the ‘Comments box’. 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 the deficit caused by the SCI will typically be handled as not normal. Each classification variable resulting in defined motor, sensory levels, or neurological level of injury (NLI), or AIS grade which is affected by the ‘*’-tagged scores, should also be designated with a ‘*’. By this method, it is clearly indicated that the classification results are based on clinical interpretation of the recorded scores.
In some cases, it might be difficult to decide whether a classification variable should be tagged or not. To simplify this decision process the following general approach is recommended: First, the classification should be performed on the basis of the examined scores. Then, the “*”-tagged scores should be replaced with the ones based on clinical judgment and a re-classification should be performed. Finally, all differing classification variables (e.g. motor and sensory levels, NLI, AIS grade) should be tagged with a ‘*’. With the new non-SCI taxonomy and the availability of the real examination scores, 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, which should be noted as ‘ND’.
- The Zone of Partial Preservation (ZPP) definition has been refined. The ZPPs represent important pieces of information for the characterization of a patient’s neurological status. Additionally, ZPPs are among the most important predictors of neurological recovery. In the 2011 ISNCSCI revision and the 2015 update, ZPPs were only defined for complete (ASIA Impairment Scale (AIS) A) injuries with no sensorimotor function in the most caudal sacral segments. Recording ZPPs only in cases with totally lost sensation (absent deep anal pressure (DAP), absent light touch (LT), absent pin prick (PP)) in S4-5 and lost sacral motor function (no voluntary anal contraction (VAC)) is not intuitive and restricts the value of ZPP for effective clinical communication to AIS A lesions only. Therefore, the ZPP rules were modified and are no longer based on the AIS grade. Motor ZPPs are now defined and should be documented in all cases including patients with incomplete injuries with absent VAC. The sensory ZPP on a given side is defined in the absence of sensory function in S4-5 (LT, PP) on this 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 (NA)”. In cases with absent DAP, a sensory ZPP can be defined on one side (assuming also absent LT and PP sensation in S4-5 on this side), while it may not necessarily be applicable (and should be noted as ‘NA’) on the other side if there is present LT or PP at S4-5.
It has to be emphasized that in complete lesions (AIS A) the new ZPP definition is 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 AIS B graded subject without VAC, the innervation segment of this non-key muscle is determining the motor ZPP on this side.
An analysis of ISNCSCI datasets from a large database (European Multicenter Study about Spinal Cord Injury – EMSCI) found that among the AIS B lesions a motor ZPP with an extent greater than zero segments could be determined with the new definition in 66% of all cases. Among the AIS C lesions, 55% had absent VAC. This means that in one-third of the incomplete patients meaningful ZPPs can be provided with the new definition. A deeper analysis of the EMSCI dataset revealed that the prognosis of the lower extremity motor score after one year is more reliable with the new definition of the ZPP. More details about these results will be published at a later date.
The changes introduced by the 8th ISNCSCI edition have already been integrated into the new booklet and worksheet. The International Standards Committee and the Education Committee are working hard to implement the new definitions into the online training tool InSTeP. A current effort is to publish a journal paper summarizing the changes of the recent revision together with sample cases for better illustration as soon as possible.
In summary, the 2019 ISNCSCI revision represents another milestone in the continuous evolution of the ISNCSCI towards the most inclusive assessment of people with SCI.