NIH Stroke Scale Scoring and Assessment

Understanding the NIH Stroke Scale Motor Arm Assessment

• The American Heart Association recommends using the NIH Stroke Scale (NIHSS) to assess the severity of neurological impairment after stroke, with scores ranging from 0 to 42, where higher scores indicate more severe strokes 2
• Item 5 of the NIHSS specifically evaluates motor function in the arms using the following scoring criteria:
  • 0 = No drift (arm holds 90 degrees for full 10 seconds) 1
  • 1 = Drift (arm holds 90 degrees but drifts down before full 10 seconds) 2
  • 2 = Some effort against gravity (arm cannot get to or maintain 90 degrees but has some effort against gravity) 1
  • 3 = No effort against gravity (arm falls) 1
  • 4 = No movement at all 1
  • X = Unable to assess due to amputation, fusion, fracture, etc. 1

Clinical Assessment Technique

• The proper technique for assessing motor arm function involves having the patient extend the arm palm down at 90 degrees (if sitting) or 45 degrees (if supine) and hold for 10 seconds 1
• When a limb falls completely to the bed without any resistance to gravity or any movement whatsoever, the appropriate score is 4, indicating severe motor pathway damage 1

Clinical Significance and Implications

• Motor deficits are among the most common manifestations of stroke and are important contributors to the overall NIHSS score, with higher scores correlating with poorer outcomes 2
• Higher NIHSS scores, particularly those >20, indicate large strokes with poor prognosis 3
• Complete paralysis of a limb (score of 4) contributes significantly to functional disability 2

Common Pitfalls in Assessment

• Do not confuse a score of 3 (no effort against gravity but some movement) with a score of 4 (no movement at all) 1