# NIH Stroke Scale (NIHSS) Calculator
> Free NIH Stroke Scale (NIHSS) calculator. Enter all 13 items and get the total + severity band (minor, moderate, severe). Based on the NINDS NIHSS v2.0. Clinician decision support.

## Overview

The NIH Stroke Scale (NIHSS) is the most widely used quantitative stroke severity assessment. It was developed by the NINDS and is the primary tool used to monitor stroke severity in acute ischaemic stroke care, including thrombolytic and thrombectomy decision-making. The scale comprises 13 examination items (1a, 1b, 1c plus 2–11) scored 0 to 4 (some items 0 to 3 or 0 to 2). The total ranges 0–42. AHA/ASA acute stroke guidelines reference NIHSS thresholds (e.g. ≥ 6 commonly drives consideration of mechanical thrombectomy with appropriate imaging) but exact cutoffs are guideline- and institution-specific.

## Who this is for

- Emergency physicians and stroke teams
- Neurology residents on the stroke service
- Hospitalists co-managing acute stroke patients

## How to interpret the result

| Score / band | Meaning |
|---|---|
| 0 | No measurable stroke symptoms. |
| 1–4 | Minor stroke. |
| 5–15 | Moderate stroke. |
| 16–20 | Moderate-to-severe stroke. |
| ≥ 21 | Severe stroke. |

## Cited source

**AHA/ASA Guidelines for Early Management of Acute Ischaemic Stroke** (2019) — AHA / ASA

_Primary publication:_ NINDS NIH Stroke Scale v2.0

## FAQs

### Is the NIHSS a complete stroke evaluation?

No. NIHSS quantifies severity; it does not replace neuroimaging, history, or vascular imaging. It does not capture posterior-circulation stroke well.

### What NIHSS supports thrombectomy?

AHA/ASA 2019 commonly references NIHSS ≥ 6 in conjunction with confirmed large-vessel occlusion as supporting consideration of mechanical thrombectomy within established time windows. Verify against the current guideline and institutional protocol.

### Can a low NIHSS rule out stroke?

No. Posterior-circulation strokes often present with low NIHSS but significant disability. Always integrate exam, imaging, and clinical context.

### Are clinicians required to be NIHSS-certified to use the scale?

AHA, NINDS, and most stroke centres require certification for hospital-based stroke documentation. This calculator is for educational use; document via the certified examiner per institutional policy.

### Does NIHSS need to be repeated?

Yes. Most stroke protocols include serial NIHSS — pre-thrombolysis, post-thrombolysis, post-thrombectomy, and at neurological worsening — to track response.

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_Rounds AI is a citation-first clinical AI assistant. It supports clinical reasoning by surfacing cited information and is not a substitute for independent clinical judgement._