NIH Stroke Scale (NIHSS) — Free Online Calculator
Neurological Assessment
NIHSS Score
0
No stroke symptoms
About This Calculator
The National Institutes of Health Stroke Scale (NIHSS) is a systematic assessment tool that provides a quantitative measure of stroke-related neurological deficit. It is used to evaluate the severity of acute stroke, guide treatment decisions (including thrombolytic therapy eligibility), and predict patient outcomes. The NIHSS evaluates 11 items across 15 assessments, with scores ranging from 0 (no deficit) to 42 (maximum deficit).
Formula
Interpretation
| NIHSS Score | Stroke Severity |
|---|---|
| 0 | No stroke symptoms |
| 1 – 4 | Minor stroke |
| 5 – 15 | Moderate stroke |
| 16 – 20 | Moderate to severe stroke |
| 21 – 42 | Severe stroke |
References
Frequently Asked Questions
What NIHSS score qualifies for tPA (thrombolytic therapy)?
There is no strict NIHSS cutoff for tPA eligibility, but it is generally considered for scores ≥ 4 within the treatment window (up to 4.5 hours from symptom onset). Very mild strokes (NIHSS 0–4) may not benefit from tPA, and very severe strokes (NIHSS > 25) have higher bleeding risk.
How long does it take to perform the NIHSS?
A trained examiner can complete the NIHSS in approximately 5–8 minutes. All healthcare providers performing stroke assessments should be NIHSS-certified through standardized training programs.
Can the NIHSS miss posterior circulation strokes?
Yes. The NIHSS is weighted toward anterior circulation deficits (language, motor). Posterior circulation strokes causing vertigo, ataxia, visual field cuts, or cranial nerve palsies may receive low NIHSS scores despite significant clinical severity.
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⚠ Medical Disclaimer
This tool is for educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for clinical decisions.