π§ NIH Stroke Scale Calculator
The 15-item standardized stroke exam.
For informational purposes only, not medical advice. Consult a healthcare professional.
The NIH Stroke Scale is the standardized neurological exam for acute stroke: 15 items covering consciousness, gaze, vision, facial movement, limb strength, coordination, sensation, language, speech clarity, and attention. Each item scores deficit severity for a total of 0 to 42. It quantifies the stroke for treatment decisions, especially thrombolysis and thrombectomy, and for tracking change over hours.
Score each item per the standard NIHSS instructions and enter the values. The calculator totals the scale and names the severity band. It is a clinical tool for trained examiners: proper NIHSS certification exists because scoring technique changes results.
How to Use This Calculator
Perform the NIHSS exam in order, scoring what the patient actually does, not what you think they could do. Score untestable items per NIHSS rules (e.g., amputation, intubation have specific conventions). Enter all 15 items. Read the total and band, and document it with the exam time for serial comparison.
Perform the 15-item NIHSS exam in standard order.
Score each item 0 to its maximum per NIHSS rules.
Enter all 15 values.
Read the total, band, and document with time.
The 15 Items and Their Weights
Motor items carry the most points (0-4 each)
The scale weights motor function heaviest: each limb scores 0 to 4, so hemiplegia alone contributes 16 points. Language scores up to 3 because aphasia is disabling; neglect up to 2. Consciousness items anchor the top: a comatose patient scores across LOC items plus untestable items per convention. The scale was designed for anterior circulation strokes and underweights posterior circulation (ataxia, dysarthria get few points) and right-hemisphere deficits, a known limitation. Serial NIHSS is the standard trial outcome: improvement of 4+ points or a drop to 0-1 defines early neurological response.
Worked Example
Facial droop 1, left arm drift 1, left leg drift 1, mild aphasia 1: NIHSS is 4 / 42, in the Minor stroke band. Even small numbers matter here: a 4 with disabling aphasia can qualify for thrombolysis while a 6 of pure sensory loss might not, which is why Deficits are weighed with time window and imaging, not score alone is printed on every result.
Severity Bands and What They Drive
Zero means no measurable deficit. One to 4 is minor, though "minor" with disabling aphasia or hemianopia is not minor to the patient. Five to 15 is moderate, the classic thrombolysis consideration range. Sixteen to 20 is moderate-severe and 21+ severe, where large vessel occlusion and thrombectomy enter the picture. Higher scores predict worse outcomes and higher hemorrhage risk with thrombolysis, but the score never decides alone: time from onset, imaging, and deficit type decide with it.
Stroke Is an Emergency: Act, Do Not Score
If someone shows face droop, arm weakness, or speech trouble, call emergency services immediately: note the time symptoms started. Do not attempt a full NIHSS as a bystander; the BE-FAST screen (balance, eyes, face, arm, speech, time) is the public tool. Every minute of large vessel stroke kills about 1.9 million neurons. For informational purposes only, not medical advice. Consult a healthcare professional.
Related tools: ICH Score, ICH volume (ABC/2) and mean arterial pressure.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the NIH Stroke Scale?
A 15-item standardized neuro exam scoring stroke severity 0-42, used for treatment decisions and tracking. Higher means worse deficits.
What NIHSS is a severe stroke?
Generally 21-42 severe, 16-20 moderate-severe, 5-15 moderate, 1-4 minor. Bands guide but do not dictate treatment.
What NIHSS qualifies for tPA?
There is no strict cutoff: disabling deficits of any score can qualify within the time window, while non-disabling minor strokes often do not get tPA.
Can NIHSS be 0 with a real stroke?
Yes. Posterior circulation strokes, small subcortical strokes, and isolated deficits can score 0-1 while being genuine strokes.
How is NIHSS different from mRS?
NIHSS measures acute neurological deficit; the modified Rankin Scale measures functional outcome and disability months later.
Do I need certification to score NIHSS?
For clinical trial and hospital use, yes: NIHSS certification exists because technique affects scores. This calculator is for learning the arithmetic.
What is a good NIHSS improvement?
A drop of 4+ points or to 0-1 at 24 hours defines early neurological improvement in most trials.
Why does NIHSS underweight posterior strokes?
It was designed around anterior circulation deficits. Ataxia and cranial nerve findings get few points, so basilar strokes can look deceptively mild.
Can nurses perform the NIHSS, or only doctors?
Trained nurses do it routinely; certification courses exist specifically for nursing staff. The scale was designed to be reproducible across examiners, and studies show good agreement between trained nurses and neurologists. In stroke centers, the bedside nurse often scores it before the doctor arrives.
Does a low NIHSS mean no treatment is needed?
No. Mild strokes (NIHSS under 5) can still disable through the specific deficit involved: a score of 2 from aphasia can end a career. Treatment decisions weigh the deficit's impact on the person, not just the number. Thrombolysis and thrombectomy decisions also depend on imaging and time, not the score alone.