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Calculator · Stroke severity, for communication and comparison
NIHSS
Fifteen items, scored as observed — not as you think the patient could manage if they tried. Its real value on-call is as a shared number: it tells the stroke team what you are looking at, and repeating it later tells them whether it has changed.
What it asks
| Criterion | Points |
|---|---|
| 1a. Level of consciousness | Alert, responsive — 0 Rousable by minor stimulation — 1 Requires repeated or painful stimulation — 2 Unresponsive, or reflex responses only — 3 |
| 1b. LOC questions — the month, and their age | Both correct — 0 One correct — 1 Neither correct — 2 |
| 1c. LOC commands — open and close eyes, grip and release | Both performed — 0 One performed — 1 Neither performed — 2 |
| 2. Best gaze | Normal — 0 Partial gaze palsy — 1 Forced deviation — 2 |
| 3. Visual fields | No loss — 0 Partial hemianopia — 1 Complete hemianopia — 2 Bilateral hemianopia, or blind — 3 |
| 4. Facial palsy | Normal — 0 Minor — flattened nasolabial fold — 1 Partial — lower face — 2 Complete — upper and lower face — 3 |
| 5a. Left arm motor | No drift for 10 seconds — 0 Drift, but does not hit the bed — 1 Some effort against gravity — 2 No effort against gravity — 3 No movement — 4 |
| 5b. Right arm motor | No drift for 10 seconds — 0 Drift, but does not hit the bed — 1 Some effort against gravity — 2 No effort against gravity — 3 No movement — 4 |
| 6a. Left leg motor | No drift for 5 seconds — 0 Drift — 1 Some effort against gravity — 2 No effort against gravity — 3 No movement — 4 |
| 6b. Right leg motor | No drift for 5 seconds — 0 Drift — 1 Some effort against gravity — 2 No effort against gravity — 3 No movement — 4 |
| 7. Limb ataxia Score 0 if the limb is paralysed or the patient cannot understand | Absent — 0 Present in one limb — 1 Present in two limbs — 2 |
| 8. Sensory | Normal — 0 Mild to moderate loss — 1 Severe or total loss — 2 |
| 9. Best language | No aphasia — 0 Mild to moderate aphasia — 1 Severe aphasia — 2 Mute, or global aphasia — 3 |
| 10. Dysarthria | Normal — 0 Mild to moderate — 1 Severe, or unintelligible — 2 |
| 11. Extinction and inattention | No abnormality — 0 Inattention to one modality — 1 Profound, or to more than one modality — 2 |
How to read the score
| Score | Means | What to do |
|---|---|---|
| 0 | No measurable deficit | A zero does NOT exclude a stroke. The scale is weighted towards the anterior circulation, and a posterior stroke can score nothing at all. |
| 1–4 | Minor | Still a stroke, and still a thrombolysis conversation if the deficit is disabling. "Minor" describes the score, not the consequence. |
| 5–15 | Moderate | Give the stroke team the number and the time you took it. |
| 16–20 | Moderate to severe | Communicate now. Repeat scoring is how deterioration gets documented objectively rather than as "seems worse". |
| 21–42 | Severe | Large vessel occlusion is likely — thrombectomy is a question for this moment, not for the morning. |
Before you use it
THE NUMBER DOES NOT DECIDE ANYTHING. Thrombolysis and thrombectomy are stroke-physician decisions taken on the whole picture, the imaging and the time of onset; the score is one input to a conversation. Score what you SEE, and follow the scale's own rules for a limb that is amputated or splinted or a patient who cannot understand. A partly-completed NIHSS communicates less than an honest description — if you cannot finish it, describe what you found instead. And it is weighted to the anterior circulation: a posterior stroke with devastating ataxia and diplopia can score 1.
Source: NIH Stroke Scale; NICE NG128
Checked, and shown
Every threshold on this page was checked against its primary source by a practising doctor. Here is what that involved, and what it found.