Recommended Scoring Systems for Stroke Assessment
The National Institutes of Health Stroke Scale (NIHSS) is the primary recommended scoring system for assessing stroke severity in patients with recurrent ischemic stroke, and should be performed at presentation, within 24 hours of admission, and at discharge. 1, 2
Primary Assessment Tool: NIHSS
The NIHSS is a Class I recommendation from the American Heart Association for all stroke patients, providing critical information about stroke severity that directly influences treatment decisions including thrombolytic therapy eligibility. 1, 2
Key Features of NIHSS:
- Score range: 0-42 points, with higher scores indicating more severe neurological impairment 2, 3
- Administration time: 5-10 minutes 2
- Components: 11 core items assessing level of consciousness, visual fields, gaze, facial palsy, motor function (arms and legs), sensation, language, dysarthria, and extinction/inattention 3, 4
- Inter-rater reliability: Excellent (ICC = 0.95-0.99), making it highly reproducible across different healthcare settings 2, 5
Prognostic Value:
- NIHSS >16: Forecasts high probability of death or severe disability 2, 3
- NIHSS <6: Forecasts good recovery 2, 3
- NIHSS >20: Indicates large strokes with poor prognosis 4
- Mortality rates correlate strongly with baseline NIHSS scores 6
Required Timing of Assessment:
- At time of presentation/hospital admission (or within first 24 hours) 2, 3
- At time of acute care discharge 2, 3
- Upon transfer to rehabilitation if previous scores unavailable 2
Training Requirements:
All professionals involved in stroke care must be trained and certified in NIHSS administration by watching training videos and passing an examination to ensure accurate assessment. 2, 3
Additional Scoring System for Intracerebral Hemorrhage
For patients with intracerebral hemorrhage (ICH) rather than pure ischemic stroke, the ICH Score is the most widely used and externally validated severity scale, though NIHSS may also be useful despite ICH patients more often presenting with depressed consciousness. 1
Important Limitations and Caveats:
Posterior circulation strokes are systematically underestimated by NIHSS because symptoms like vertigo, dysphagia, and ataxia are not included in the assessment—71% of posterior circulation stroke patients present with NIHSS ≤4, yet 15% of these "minor" strokes result in poor outcomes at 3 months. 2 Thrombolytic treatment should not be withheld based solely on low NIHSS scores in suspected posterior circulation strokes. 2
Additional limitations include:
- Distal motor function and balance/gait disorders are not adequately covered 3
- Facial palsy and dysarthria items have lower inter-rater reliability compared to other components 3
- Different symptom profiles with identical median NIHSS scores can have widely disparate outcomes 7
Modified Rankin Scale for Disability Assessment
While not explicitly detailed in the provided guidelines for acute assessment, the modified Rankin Scale is referenced as the standard outcome measure for discharge disability assessment in stroke patients. 7