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

Area of Science:

• Neurology
• Stroke Rehabilitation
• Clinical Assessment

Background:

• The NIH Stroke Scale (NIHSS) is a crucial tool for assessing stroke severity.
• The Distal Motor Function (DMF) sub-score, though not currently part of the NIHSS, has been measured in stroke trials.
• The clinical utility of incorporating DMF into the NIHSS remains unexamined.

Purpose of the Study:

• To analyze the correlation between DMF and the NIHSS Motor Arm Function (MAF) sub-score.
• To evaluate the impact of IV tPA treatment on DMF.
• To determine if adding DMF enhances the overall utility of the NIHSS.

Main Methods:

• Retrieved MAF and DMF sub-scores from the NINDS rt-PA Stroke Trials.
• Correlated MAF and DMF using Spearman correlation across multiple time points.
• Assessed the effect of IV tPA on DMF and MAF using linear models and analyzed NIHSS utility with DMF inclusion via CFI.

Main Results:

• Highly significant correlation (p < 0.0001) was found between MAF and DMF.
• IV tPA accounted for 21% of the change in DMF and 39% of the change in MAF from baseline to 3 months.
• Adding DMF to the NIHSS did not improve its utility, as indicated by a decrease in CFI and clustering of DMF with MAF.

Conclusions:

• The inclusion of DMF to the NIHSS does not offer additional clinical value.
• Proximal and distal upper extremity motor function are strongly correlated post-IV tPA, with MAF showing greater improvement.
• Further investigation is warranted regarding IV tPA's role in minor strokes affecting DMF.