Including Distal Motor Function within the NIHSS: Correlation with Motor Arm Function and IV rt-PA Treatment Response

The Distal Motor Function (DMF) sub-score of the NIH Stroke Scale (NIHSS) was measured in the NINDS rt-PA Stroke Trials but is currently not included in the NIHSS. The correlation of DMF with the NIHSS Motor Arm Function (MAF) sub-score, the effect of IV tPA treatment on DMF, and whether adding DMF changes the utility of the NIHSS have not been analyzed. MAF and DMF sub-scores were retrieved from the original NINDS rt-PA Stroke Trials for both sides of the body at baseline, 2 hours, 24 hours, 7–10 days, and 3 months after IV tPA treatment. MAF and DMF scores were correlated using Spearman correlation. Clustering of DMF and MAF scores was determined using a Bentler Comparative Fit Index (CFI) to estimate variation in NIHSS when adding DMF. The effect of IV tPA on DMF and MAF was assessed using a linear model comparing changes in scores from baseline to 3 months. MAF and DMF were highly correlated (p