How Sensory and Motor Components Shape the Neurological Level of Injury

To assess the contributions of light touch (LT), pinprick (PP) and motor function in NLI determination, and evaluate how omitting LT or PP affects NLI and American Spinal Injury Association (ASIA) Impairment Scale (AIS) classification, informing evidence-based recommendations.

Secondary analysis.

National Spinal Cord Injury Model Systems (SCIMS) database.

N=7,449 individuals with traumatic spinal cord injury (AIS A-D) who had complete International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) examinations recorded between 2011 and 2023.

Not applicable.

Contribution of LT, PP, and motor scores to NLI determination; changes in NLI and AIS classification when LT or PP scores were omitted.

In spinal segments where motor function could contribute to NLI determination (C4-T1, L1-S1), motor alone uniquely determined the NLI in 29.0% of cases, versus 13.4% for PP alone and 5.5% for LT alone. By overall identification (how often a modality's finding matched the final NLI, alone or combined), motor matched 64.1%, PP 61.0%, and LT 49.7%. In segments without motor contribution (C1-C3, T2-T12), LT and PP together determined the NLI in 49.7% of cases. When they diverged, PP was the unique determinant nearly twice as often as LT (33.0% vs. 17.3%), with overall identification of 82.7% for PP and 67.0% for LT. In the full sample, removal of LT did not change the NLI in 88.6% of cases, versus 76.8% for PP. Excluding either modality led to up to 2.3% of cases being reclassified to a more severe AIS grade.

Both LT and PP contributed to NLI determination, with PP more frequently the unique determinant when findings diverged. Omitting either modality led to changes in AIS grades in a small but noteworthy subset of cases. Both modalities remain essential to NLI classification, especially where motor testing is not possible.