NIHSS Calculator — NIH Stroke Scale Online
Level of Consciousness
LOC Questions
LOC Commands
Best Gaze
Visual Fields
Facial Palsy
Motor
Motor Left Arm
Motor Right Arm
Motor Left Leg
Motor Right Leg
Limb Ataxia
Sensory
Best Language
Dysarthria
Extinction/Inattention
Trials informing thresholds
Trials in which NIHSS thresholds shaped eligibility, randomization, or interpretation of acute-stroke treatment.
- NINDS1995
Foundational IV alteplase trial establishing benefit within 3 hours of ischemic stroke onset.
- ECASS III2008
Extended the alteplase treatment window to 4.5 hours in selected ischemic stroke patients.
- WAKE-UP2018
MRI DWI-FLAIR mismatch trial supporting alteplase for wake-up and unknown-onset stroke.
- EXTEND2019
Perfusion-selected late-window alteplase trial supporting tissue-based rather than strictly time-based thrombolysis.
- PRISMS2018
Alteplase did not outperform aspirin in minor nondisabling stroke and caused more symptomatic ICH.
- DAWN2018
Clinical-imaging mismatch trial that redefined thrombectomy eligibility out to 24 hours.
- ARAMIS2023
Dual antiplatelet therapy was noninferior to alteplase in minor nondisabling stroke within 4.5 hours.
- INSPIRES2024
Atherosclerotic minor stroke and TIA trial extending the DAPT initiation window out to 72 hours.
Frequently asked questions
What is the NIHSS calculator used for?
The NIHSS (NIH Stroke Scale) calculator quantifies stroke severity across 11 domains — consciousness, gaze, visual fields, facial palsy, motor arm/leg, limb ataxia, sensory, language, dysarthria, and extinction. Scores range 0–42; higher scores indicate greater deficits. It guides tPA and EVT eligibility and predicts outcomes.
What NIHSS score qualifies for IV thrombolysis?
Most guidelines do not set a minimum NIHSS for tPA eligibility; even minor deficits may be disabling. However, a score of 0–1 with non-disabling symptoms is often treated medically. NIHSS ≥4–6 is typically required for EVT eligibility in the early window.
How often should NIHSS be performed?
NIHSS should be performed at baseline (prior to treatment), at 24 hours post-treatment, at discharge, and at 90-day follow-up per AHA/ASA guidelines. During active intervention, hourly assessments may be warranted.
Record Stroke Time Stamps