NIH Stroke Scale (NIHSS)
Standardised severity of the neurological deficit in acute stroke
- NINDS (NIH) official form
Sources last checked: 2026-10-13
NIH Stroke Scale (NIHSS)
Standardised severity of the neurological deficit in acute stroke
The total (0–42) has no official severity bands. Items marked UN are recorded but not added. Certified training (video-based) is what makes scores reproducible.
What is the NIH Stroke Scale (NIHSS)?
The NIH Stroke Scale quantifies the neurological deficit of an acute stroke across 15 examined items, giving a total from 0 to 42. It grew out of a 15-item examination scale published by Brott and colleagues in 1989 and was refined for the NINDS rt-PA trials; the current form is distributed by the US National Institute of Neurological Disorders and Stroke. It is the standard severity measure in stroke units and reperfusion trials worldwide, including those behind ESO guidance.
When to use it
- Baseline severity in every patient with suspected acute stroke, before reperfusion decisions.
- Serial reassessment after thrombolysis or thrombectomy to detect improvement or deterioration.
- Standardised handover between emergency team, stroke unit and neuroradiology.
- Documentation for stroke registries, quality indicators and clinical trials.
When not to use it
- As a replacement for imaging — the score cannot separate ischaemia from haemorrhage or a mimic.
- To measure long-term disability or independence; use the modified Rankin Scale for that.
- To dismiss posterior-circulation stroke: vertigo, gait ataxia and dysphagia are poorly captured, so a low score can coexist with a basilar occlusion.
How it is calculated
| Criterion | Points |
|---|---|
| 1a. Level of consciousness | |
| Alert, keenly responsive | 0 |
| Not alert, arousable by minor stimulation | 1 |
| Needs repeated or strong/painful stimulation | 2 |
| Reflex responses only, or totally unresponsive | 3 |
| 1b. LOC questions (month, age) | |
| Answers both correctly | 0 |
| Answers one correctly | 1 |
| Answers neither correctly | 2 |
| 1c. LOC commands (eyes, hand grip) | |
| Performs both tasks | 0 |
| Performs one task | 1 |
| Performs neither task | 2 |
| 2. Best gaze | |
| Normal | 0 |
| Partial gaze palsy | 1 |
| Forced deviation or total gaze paresis | 2 |
| 3. Visual fields | |
| No visual loss | 0 |
| Partial hemianopia | 1 |
| Complete hemianopia | 2 |
| Bilateral hemianopia (incl. cortical blindness) | 3 |
| 4. Facial palsy | |
| Normal symmetrical movement | 0 |
| Minor (flattened nasolabial fold) | 1 |
| Partial (lower face) | 2 |
| Complete (upper and lower face) | 3 |
| 5a. Motor arm — left | |
| No drift for 10 s | 0 |
| Drift before 10 s, does not hit bed | 1 |
| Some effort against gravity | 2 |
| No effort against gravity, limb falls | 3 |
| No movement | 4 |
| UN — amputation or joint fusion (not added) | 0 |
| 5b. Motor arm — right | |
| No drift for 10 s | 0 |
| Drift before 10 s, does not hit bed | 1 |
| Some effort against gravity | 2 |
| No effort against gravity, limb falls | 3 |
| No movement | 4 |
| UN — amputation or joint fusion (not added) | 0 |
| 6a. Motor leg — left | |
| No drift for 5 s | 0 |
| Drift before 5 s, does not hit bed | 1 |
| Some effort against gravity | 2 |
| No effort against gravity, falls immediately | 3 |
| No movement | 4 |
| UN — amputation or joint fusion (not added) | 0 |
| 6b. Motor leg — right | |
| No drift for 5 s | 0 |
| Drift before 5 s, does not hit bed | 1 |
| Some effort against gravity | 2 |
| No effort against gravity, falls immediately | 3 |
| No movement | 4 |
| UN — amputation or joint fusion (not added) | 0 |
| 7. Limb ataxia | |
| Absent | 0 |
| Present in one limb | 1 |
| Present in two limbs | 2 |
| UN — amputation or joint fusion (not added) | 0 |
| 8. Sensory | |
| Normal | 0 |
| Mild-to-moderate loss | 1 |
| Severe to total loss | 2 |
| 9. Best language | |
| No aphasia | 0 |
| Mild-to-moderate aphasia | 1 |
| Severe aphasia | 2 |
| Mute, global aphasia | 3 |
| 10. Dysarthria | |
| Normal | 0 |
| Mild-to-moderate | 1 |
| Severe, unintelligible or anarthric | 2 |
| UN — intubated or other physical barrier (not added) | 0 |
| 11. Extinction and inattention (neglect) | |
| No abnormality | 0 |
| Inattention or extinction in one modality | 1 |
| Profound hemi-inattention or more than one modality | 2 |
Clinical pearls and limitations
- The total (0–42) has no official severity bands. Items marked UN are recorded but not added. Certified training (video-based) is what makes scores reproducible.
- Score what the patient does, not what you think they could do, and record each item before moving on — do not go back and change answers.
- Right-hemisphere strokes score lower than left-hemisphere strokes of similar size because language items weigh heavily.
- There are no official severity categories for the total; describe the deficit and quote the number rather than labelling 'minor' by score alone.
- UN (untestable) is only allowed for amputation or joint fusion (motor items, ataxia) and intubation or physical barriers (dysarthria); it adds no points.
- Certification with the official video training measurably improves inter-rater reliability.
Frequently asked questions
What is the maximum NIHSS score?
42 is the arithmetic maximum. In practice a comatose, quadriplegic patient scores 40, because the form scores limb ataxia as absent (0) when the limbs are paralysed.
Is a low NIHSS a reason not to treat?
No single NIHSS threshold decides reperfusion. Guidelines weigh whether the deficit is disabling — an isolated aphasia or hemianopia can be disabling at a score of 2–3.
How is an amputated arm scored?
As UN (untestable) with a written explanation. It is recorded but contributes nothing to the total.
Is the NIHSS free to use?
The form is published and distributed free of charge by NINDS. Formal certification courses are offered separately by training providers.
Evidence and guidelines
- Primary source: NINDS NIH Stroke Scale form (rev. 10/1/2003), National Institute of Neurological Disorders and Stroke. Based on Brott T et al. Measurements of acute cerebral infarction: a clinical examination scale. Stroke 1989;20(7):864-870.
- Brott T et al. Measurements of acute cerebral infarction: a clinical examination scale. Stroke 1989;20(7):864-870.
- Lyden P et al. Improved reliability of the NIH Stroke Scale using video training. Stroke 1994;25(11):2220-2226.
- Berge E et al. European Stroke Organisation (ESO) guidelines on intravenous thrombolysis for acute ischaemic stroke. Eur Stroke J 2021;6(1):I-LXII.
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