Nih Stroke Calculator - 11-Item Severity Tally
Use this NIH stroke scale calculator to score the 11 NINDS items, sum the sub-scores, and read the published severity band with tPA context.
Nih Stroke Calculator
Results
What Is the NIH Stroke Scale Calculator?
The NIH stroke scale calculator is a structured bedside tally for the 11-item National Institutes of Health Stroke Scale, the standard scoring tool used by stroke teams to measure how much a suspected stroke is affecting a patient. Pick the highest-matching option in each item, sum the points, and the result is a 0 to 42 total that maps to a published severity band and to the tPA decision-support thresholds the team uses during the acute workup.
- • Acute stroke triage: An emergency physician, nurse, or trainee scoring a patient within the 4.5 hour tPA window.
- • Serial reassessment: A neurology or stroke-unit team repeating the assessment at 24 and 72 hours after admission.
- • Research and trial screening: A coordinator applying the published eligibility thresholds for a stroke trial that uses NIHSS cutoffs.
- • Teaching and simulation: An instructor walking learners through the item-by-item scoring on a simulated case.
The calculator follows the 15 sub-items (1a, 1b, 1c, 2, 3, 4, 5a, 5b, 6a, 6b, 7, 8, 9, 10, 11) the NINDS published in 1989 for the original rt-PA trial.
A low score (0 to 4) is a strong basis to look for a stroke mimic, the moderate band (5 to 15) lines up with most tPA-eligible presentations, and a score above 16 is a red flag for severe deficit.
When a stroke patient has been on heparin and the platelet count is falling, the 4TS Score calculator runs in parallel to track the related thrombocytopenia risk.
How the NIH Stroke Scale Calculator Works
The calculator walks through the 15 NINDS sub-items, picks the highest-matching option in each, and sums the numbers into a 0 to 42 total.
- 1a LOC responsiveness (0-3): How the patient responds to voice or pain.
- 1b LOC questions (0-2): Both, one, or neither of the month and age questions correct.
- 1c LOC commands (0-2): Both, one, or neither of the open-eyes and grip-hand tasks correct.
- 2 Best gaze (0-2): Horizontal eye tracking, partial gaze palsy, or forced deviation.
- 3 Visual fields (0-3): No loss, partial hemianopia, complete hemianopia, or bilateral blindness.
- 4 Facial palsy (0-3): Minor, partial, or complete paralysis of one side of the face.
- 5a and 5b Motor arm (0-4 each): Drift-based options scored for each arm.
- 6a and 6b Motor leg (0-4 each): Same drift-based options as the arms, scored for each leg.
- 7 Limb ataxia (0-2): Absent, in one limb, or in two or more limbs.
- 8 Sensory (0-2): No loss, mild-to-moderate loss on one side, or severe-to-total loss on one side.
- 9 Best language (0-3): No aphasia, mild-to-moderate, severe, or mute with no comprehension.
- 10 Dysarthria (0-2): Clear, mild-to-moderate slurring, or speech that cannot be understood.
- 11 Extinction and inattention (0-2): No neglect, inattention in one modality, or hemi-inattention in two or more.
When 1a scores 3 (totally unresponsive), the official NINDS rules tell the scorer to apply default coma scores. The calculator carries those default options in the select menu so the scorer simply picks the right option.
The numbers and the items are tied back to the published severity bands: 0, 1 to 4, 5 to 15, 16 to 20, and 21 to 42.
Worked Example: Right MCA minor stroke, total 4
1a=0, 1b=0, 1c=0, 2=0, 3=0, 4=1, 5a=1, 5b=0, 6a=0, 6b=0, 7=0, 8=1, 9=1, 10=0, 11=0.
0 + 0 + 0 + 0 + 0 + 1 + 1 + 0 + 0 + 0 + 0 + 1 + 1 + 0 + 0 = 4.
4 of 42
Minor stroke band. The arm drift, mild facial droop, mild aphasia, and sensory change point to a small left cortical lesion.
According to National Institute of Neurological Disorders and Stroke (NINDS), the NIHSS is composed of 11 items scored 0 to 4, with a maximum possible total of 42 points.
When a severe NIHSS score triggers a tPA eligibility review, the GFR Calculator supports the kidney-function check that affects contrast imaging and medication clearance.
Key Concepts Behind the NIHSS
Four concepts help the team read the NIHSS the way the stroke scale was designed to be used.
Default coma scores
When 1a responsiveness is 3, the scorer applies the default scores for items that cannot be tested in an unresponsive patient.
Severity bands
The 0, 1 to 4, 5 to 15, 16 to 20, and 21 to 42 bands give the team a one-glance summary of how much deficit the patient has.
Hemispheric weighting
Seven of the 42 points are tied to verbal or comprehension skills, so a left-hemisphere stroke with aphasia can score higher than a right-hemisphere stroke of the same size.
Repeatability
Inter-rater agreement is high when the test is done the same way twice, which is why most stroke protocols score at baseline, 24 hours, and 72 hours.
Reading the items together is what makes the score useful. A high motor score without a matching language or gaze deficit suggests a subcortical pattern, while combined aphasia, gaze preference, and right hemiparesis point to a left MCA stroke.
When the NIHSS workup points to a stroke mimic, the Age-Adjusted D-Dimer Calculator helps interpret the d-dimer that often runs alongside the NIHSS during the same emergency workup.
How to Use This NIH Stroke Scale Calculator
Work through the items in the NINDS order and pick the highest-matching option in each.
- 1 Score the level of consciousness: Start with 1a, 1b, and 1c. Use the default coma scores if 1a is 3.
- 2 Score the right hemisphere items: Best gaze, visual fields, and facial palsy cover the cortical screen.
- 3 Score motor arm and motor leg: Test each arm for 10 seconds and each leg for 5 seconds.
- 4 Score the remaining items: Ataxia, sensory, language, dysarthria, and extinction cover the rest of the assessment.
- 5 Read the severity band and the tPA context: Add the sub-scores, look at the band, and use the tPA context to guide the next conversation.
A 72-year-old arrives 2 hours after onset. 1a=0, 1b=1, 1c=0, 2=1, 3=1, 4=2, 5a=0, 5b=3, 6a=0, 6b=2, 7=0, 8=1, 9=2, 10=1, 11=0. Total 14, in the moderate 5 to 15 band.
Once the acute NIHSS review is in the chart, the Barthel Index gives the post-acute team a quick way to track activities of daily living during recovery.
Benefits of Using an NIH Stroke Scale Calculator
A bedside calculator keeps the tally consistent, traceable, and easy to defend in the chart.
- • Standardised review across providers: Emergency physicians, neurologists, nurses, and pharmacists all use the same 11 items.
- • Transparent record-keeping: Each sub-score and the total can be quoted in the chart note for the next reviewer.
- • Quick link to the severity band: The calculator ties the total to the published bands so the user does not re-look up the cut points.
- • Built-in tPA decision context: The tPA context line summarises where the score sits in the Adams 1999 outcome prediction.
The NIHSS was designed to make the pretest severity of stroke easier to discuss at the bedside. It does not diagnose stroke, does not replace imaging, and does not order treatment on its own.
A patient with a high NIHSS score is often admitted to a neuro-intensive care unit, where the APACHE II Calculator supports the broader ICU severity review on the same admission.
Factors That Affect the NIHSS Result
Several things can move the score up or down that the team should keep in mind.
Stroke location and size
A small cortical stroke can score higher than a larger subcortical stroke because seven of the 42 points are tied to language. The team should always pair the score with imaging.
Time since symptom onset
The score can drift by several points in the first 24 hours, especially after tPA or thrombectomy. The same patient scored at hour 1 and at hour 24 will not have the same total.
Patient cooperation and consciousness
A patient who cannot follow commands because of aphasia, sedation, or intubation will have a higher total. The default coma scores and the intubation note on dysarthria are the official ways to handle this.
Pre-existing deficits
Old stroke, prior weakness, or a baseline visual field cut will all add to the score without representing a new lesion. Document the baseline before assigning a new total to the acute event.
- • The tool is a structured bedside tally, not a diagnostic test. A 0 score does not rule out stroke, especially for posterior circulation events.
- • Inter-rater agreement is high but not perfect. The band is the safer thing to document and quote to the next reviewer.
Bleeding risk, kidney function, blood pressure, glucose, and the time window all matter, but those are not part of the NIHSS itself.
According to Lyden et al., Stroke 1999, an increase of 1 point on the NIHSS decreases the likelihood of an excellent recovery by about 17 percent, and a baseline above 16 strongly predicts mortality.
Atrial fibrillation is one of the most common stroke mechanisms, and an ECG Heart Rate Calculator gives the bedside team a fast heart-rate check while the NIHSS is being scored.
Frequently Asked Questions
Q: What is the NIH stroke scale used for?
A: The NIH stroke scale is a structured 11-item bedside tool used by stroke teams to measure how much a suspected stroke is affecting a patient. Each item scores a specific ability, the sub-scores are added, and the total falls into a published severity band.
Q: How is the NIH stroke scale scored?
A: Pick the highest-matching option in each of the 11 items. The level of consciousness has 3 sub-items (1a, 1b, 1c), the motor arm and motor leg items are scored for each side, and the other items are scored once. Add the sub-scores to a 0 to 42 total.
Q: What does a NIHSS score of 0 mean?
A: A total of 0 means no detectable deficit on the 11 items tested. A 0 score does not rule out a posterior circulation stroke or a small cortical stroke, so clinical exam and imaging still matter when the score is 0.
Q: What is a moderate stroke on the NIHSS?
A: The 5 to 15 band is classified as a moderate stroke. Most tPA-eligible patients present in this range, and the band is the one most clinical trials use to describe a moderate deficit.
Q: What NIHSS score qualifies for tPA?
A: The AHA and ASA guidelines do not set a single NIHSS cut point for tPA. Trials have used minimum and maximum scores for inclusion, and Adams 1999 showed a baseline above 16 strongly predicts death or severe disability. The score supports, but does not replace, the clinical and imaging review.
Q: Can a NIHSS score of 0 still be a stroke?
A: Yes. A 0 means no deficit on the items tested, but posterior circulation strokes and small cortical strokes can score 0 on the NIHSS and still need imaging and clinical follow-up.