Functional motor preservation below the level of injury in subjects with American Spinal Injury Association Impairment Scale grade A spinal cord injuries.

OBJECTIVE

To assess how frequently subjects with spinal cord injuries (SCIs) classified as American Spinal Injury Association Impairment Scale (AIS) grade A have substantial preserved motor function below the neurologic level of injury, despite having no preserved sensory or motor function at the S4-5 spinal cord segment.

DESIGN

Analysis of the European Multicenter Study about Spinal Cord Injury database to determine how frequently subjects assessed as AIS A would have been AIS D based on motor scores alone (ie, had scores of ≥3 in at least half of the International Standards for Neurological Classification of Spinal Cord Injury [ISNCSCI] key muscles below the neurologic level of injury, despite having no sacral sparing).

SETTING

Eighteen European centers.

PARTICIPANTS

Individuals with traumatic SCI at any level (total of 2557 assessments).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

ISNCSCI assessments.

RESULTS

Over the first year after SCI (with assessments at approximately 1, 4, 12, 24, and 48wk) and for all rostrocaudal levels of injury, only 3.2% of AIS A assessments were found to meet the AIS D motor score criteria. The percentage was highest for lumbar (16.3%) and lower thoracic (4.4%) SCI. No trends were observed across time points.

CONCLUSIONS

These results suggest that the low frequency of individuals with an AIS A classification and high levels of motor function are not a significant concern in subject recruitment for clinical trials, unless the level of SCI is within the lumbar cord.