NIH Stroke Scale (NIHSS)

A 15-item examination that quantifies stroke severity at presentation and over time.

Clinician-administered by trained and certified raters; approximately 10 minutes.
15 items covering consciousness, gaze, visual fields, facial palsy, limb strength, ataxia, sensation, language, dysarthria, and extinction.
Total 0 to 42; higher scores indicate greater severity.
Bands: 0 no deficit, 1 to 4 minor, 5 to 15 moderate, 16 to 20 moderate-severe, 21 to 42 severe.

What it measures

The NIHSS tests the major functions affected by stroke across 15 items: level of consciousness and responsiveness, horizontal gaze, visual fields, facial palsy, arm and leg motor function, limb ataxia, sensation, aphasia, dysarthria, and extinction or inattention. Each item is scored 0 (normal) up to 2, 3, or 4 depending on the domain.

What the result tells you

The total (0 to 42) is the primary measure of stroke severity. It predicts outcome and guides treatment decisions, including eligibility for thrombolysis and thrombectomy. Serial scores track recovery or deterioration. In research, it is the standard efficacy endpoint in acute stroke trials.

Used for

Stroke

Evidence, psychometrics and provenance

Psychometrics

Inter-rater reliabilityκ ≈ 0.69

Inter-rater agreement (kappa) with unstructured rating; rises above 0.90 with video training.

Predictive validity: Strong predictor of 3-month functional outcome

References

1.Brott T, Adams HP Jr, Olinger CP, et al. Measurements of acute cerebral infarction: a clinical examination scale. Stroke. 1989;20(7):864-870.

This assessment uses a validated instrument and is reference information, not a diagnosis.