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