A three-item score that screens patients with suspected stroke for a severe stroke or a large vessel occlusion.
Result
Answer the three questions to see the score.
Sources
4 studies
4
studies
249
citations
61
PubMed papers
Evidence
Known limitations
In the derivation cohort (a thrombolysis trial) a score of 2 or more identified a severe stroke (NIHSS 15 or more) with a sensitivity of 89% and specificity of 73%; in a second trial cohort it identified a large vessel occlusion with a sensitivity of 83% and specificity of 40%.
Stroke: Journal Metrics Score 1.9, Q2 · cited 249 times
PubMed · Free full text · DOI
In 664 patients with ischemic stroke and vessel imaging at a New York hospital, scored from recorded NIHSS items, a score of 2 or more was 70% sensitive and 87% specific for a large vessel occlusion, so about 1 in 3 occlusions would be missed; only gaze deviation and arm weakness were independently associated with it.
J Stroke Cerebrovasc Dis: Journal Metrics Score 2.8, Q1 · cited 26 times
PubMed · Free full text · DOI
In a pilot study of 58 patients scored by EMS providers in the field as C-STAT, a positive score identified a large vessel occlusion with a sensitivity of 71% (95% CI 29–96) and specificity of 70%, and a severe stroke with 77% and 84%.
Prehosp Emerg Care: Journal Metrics Score 1.8, Q2 · cited 78 times
In a systematic review for the 2018 American Heart Association guidelines, no prehospital large vessel occlusion scale had both high sensitivity and high specificity; systems that use these scales for triage will miss some patients with an occlusion and milder stroke.
The original paper has been cited 249 times, and 61 PubMed articles mention the Cincinnati Prehospital Stroke Severity Scale in their title or abstract. Citation counts from OpenAlex and article counts from PubMed, retrieved November 11, 2026. Journal Metrics Scores and quartiles are from this site’s current release; follow the journal name for details.
After the result
Score 2 or more · Score 0 or 1 · Any score
Treat as a possible large vessel occlusion. A stroke is still possible. Imaging decides treatment.
Next steps
Avoid common errors
5 common errors to avoid
and 3 more
When the score misleads
1Not a stroke screen
The scale estimates severity once a stroke is suspected. Use a stroke recognition tool such as the Cincinnati Prehospital Stroke Scale or FAST first.
2Posterior circulation strokes
Basilar artery occlusion can present with vertigo, ataxia or a reduced level of consciousness and score low, because the scale was built from anterior circulation signs.
3The consciousness item needs both parts
One wrong answer alone, or one failed command alone, scores 0. Only a patient who misses a question and also fails a command gets the point.
4Arm drift is not enough
The arm point is for an arm that falls to the bed within 10 seconds or cannot be lifted (NIHSS 2 or more). A drift that stops above the bed scores 0.
5Mimics score too
Seizures with postictal weakness, hypoglycemia and migraine can produce gaze deviation or weakness and a positive score.
Formula
Gaze deviation 2, consciousness questions and commands 1, arm weakness 1; total 0 to 4, positive at 2 or more.
Gaze deviation 2, consciousness questions and commands 1, arm weakness 1; total 0 to 4, positive at 2 or more.
Items and score ranges
| Finding | NIHSS item | Points |
|---|---|---|
| Conjugate gaze deviation | NIHSS best gaze 1 or 2 | 2 |
| Level of consciousness questions and commands | NIHSS 1b and 1c both 1 or more | 1 |
| Arm weakness | NIHSS motor arm 2, 3 or 4 on either side | 1 |
| Result | Score | Meaning |
|---|---|---|
| Below the cut-off | 0 to 1 | A score of 0 or 1 makes a severe stroke or large vessel occlusion less likely, but does not rule it out; in the external validation about 1 in 3 patients with a large vessel occlusion scored below 2. |
| Suggests a severe stroke or large vessel occlusion | 2 to 4 | A score of 2 or more predicted a severe stroke (NIHSS 15 or more) and a large vessel occlusion in the original study; regional protocols may use it to choose a thrombectomy-capable stroke center. |
Katz 2015
Renamed C-STAT
Only two items carried the signal
Test cases
3 published cases, each also a test case
3 published cases; the calculator reproduces every score.
Worked examples
A 54-year-old man with infective endocarditis had left-sided weakness (grade III strength), a left facial palsy and dysarthria from a right parietal infarct. The report scores the NIHSS item by item: 2 for the left arm, and nothing for gaze or the consciousness items.
“NIHSS score was 8 points (facial palsy 2 points, left upper limb 2 points, left lower limb 2 points, sensation 1 point, dysarthria 1 point).”
We derived the CPSSS from the authors’ NIHSS items: motor arm 2 gives the arm point; gaze and items 1b and 1c were 0. A clear hemiparesis still scores below the cut-off.
Entered as: Are both eyes deviated to one side (conjugate gaze deviation)?: No: eyes move fully both ways (0); Does the patient answer at least one of two questions wrongly (age, current month) AND fail at least one of two commands (close and open the eyes, grip and release the non-paretic hand)?: No: answers both questions or does both commands (0); Does either arm fall to the bed within 10 seconds, or not lift against gravity at all, when held at 90° (sitting) or 45° (lying)?: Yes: an arm falls to the bed or cannot be lifted (1).
Source: Li R et al., Cureus 2025 (PubMed · Free full text · DOI)
A 44-year-old man with infective endocarditis had a rightward conjugate gaze deviation, left hemiplegia, left hemianopia, anosognosia and dysarthria, but could identify objects and follow simple commands. The NIHSS was 16.
“Despite demonstrating the ability to identify objects and follow simple commands”
Gaze deviation (2) and a plegic left arm (1). The consciousness point needs both a wrong answer and a failed command; this patient followed commands, so it is 0.
Entered as: Are both eyes deviated to one side (conjugate gaze deviation)?: Yes: gaze deviation or palsy (2); Does the patient answer at least one of two questions wrongly (age, current month) AND fail at least one of two commands (close and open the eyes, grip and release the non-paretic hand)?: No: answers both questions or does both commands (0); Does either arm fall to the bed within 10 seconds, or not lift against gravity at all, when held at 90° (sitting) or 45° (lying)?: Yes: an arm falls to the bed or cannot be lifted (1).
Source: Vasconcelos M et al., Cureus 2023 (PubMed · Free full text · DOI)
A 74-year-old woman with a ruptured abdominal aortic aneurysm presented as a stroke alert: minimally responsive, with leftward gaze deviation, right-sided hemiparesis, complete aphasia and inability to follow commands. The left limbs withdrew to pain; drift could not be tested. The NIHSS was 24. CT angiography showed no large vessel occlusion; MRI later showed multiple embolic infarcts.
“She was noted to be minimally responsive, with a leftward gaze deviation, right-sided hemiparesis, complete aphasia, and inability to follow commands.”
Gaze deviation (2); an aphasic patient who cannot answer and does not follow commands (1); the right arm (1). The right arm point is our inference: the admission drift test could not be done, but at discharge, after improvement, the right arm still had no effort against gravity. A positive score here did not mean a large vessel occlusion.
Entered as: Are both eyes deviated to one side (conjugate gaze deviation)?: Yes: gaze deviation or palsy (2); Does the patient answer at least one of two questions wrongly (age, current month) AND fail at least one of two commands (close and open the eyes, grip and release the non-paretic hand)?: Yes: misses a question and a command (1); Does either arm fall to the bed within 10 seconds, or not lift against gravity at all, when held at 90° (sitting) or 45° (lying)?: Yes: an arm falls to the bed or cannot be lifted (1).
Source: Malani E et al., Cureus 2026 (PubMed · Free full text · DOI)
FAQ
6 questions and answers
and 4 more answers
Questions
A three-item scale for patients with suspected stroke, built from parts of the NIH Stroke Scale: conjugate gaze deviation (2 points), wrong answers to the level of consciousness questions together with failed commands (1 point), and an arm that cannot be held up for 10 seconds (1 point). The total runs from 0 to 4, and 2 or more suggests a severe stroke or a large vessel occlusion.
No. The older Cincinnati Prehospital Stroke Scale (facial droop, arm drift, speech) asks whether a stroke is likely. The severity scale (CPSSS) is used once a stroke is suspected, to ask whether it is likely to be severe or caused by a large vessel occlusion. The severity scale was later renamed the Cincinnati Stroke Triage Assessment Tool (C-STAT).
In the original study, built from stroke trial data, a score of 2 or more identified a severe stroke (NIHSS 15 or more) with a sensitivity of 89% and specificity of 73%, and a large vessel occlusion with a sensitivity of 83% and specificity of 40%. In an external validation it was 70% sensitive and 87% specific for a large vessel occlusion. Many emergency medical services use a positive screen to consider taking the patient to a thrombectomy-capable center, following their regional protocol.
No. In the external validation in a New York hospital, about 1 in 3 patients with a large vessel occlusion scored below 2. Posterior circulation strokes in particular can score 0, because the scale does not test gait, vision or coordination.
The point needs two things: at least one wrong answer to the two questions (the patient’s age and the current month) and at least one failed command out of two (close and open the eyes, grip and release the non-paretic hand). A patient who cannot speak counts as answering wrongly. A patient who answers correctly but fails a command scores 0 on this item.
The field evidence is thin. In a small prospective pilot study of EMS providers using it as C-STAT (58 patients, few with an occlusion), a positive score had a sensitivity of 71% (95% CI 29–96) and specificity of 70% for a large vessel occlusion. A 2018 systematic review for the American Heart Association found that no prehospital scale combines high sensitivity with high specificity.
Further reading
7 references with PubMed and DOI links
7
references
5
free full text
From Katz BS et al., Stroke 2015 to the newest case reports.
References
Contributed by Dr. Meng Zhao (MD · Former Neurosurgeon · Medical AI Researcher), from the original publications listed here. Last updated November 11, 2026. LinkedIn
The calculator code is tested against every worked example on this page before each release.
This calculator supports, and does not replace, clinical judgment. It is meant for healthcare professionals and is not medical advice for patients. Report an error through the contact page.
clinical grade of aneurysmal subarachnoid hemorrhage, I to V.
total calcium adjusted for albumin, in mg/dL or mmol/L.
stroke severity from 15 bedside items, 0 to 42.
MAP from systolic and diastolic pressure, against the 65 mm Hg target.
eye, verbal and motor scores for preverbal children, 3 to 15.
oxygenation ratio with the Berlin ARDS severity ranges.
serum sodium corrected for high glucose, Katz or Hillier factor.
sodium − (chloride + bicarbonate), with the albumin-corrected gap.
urea nitrogen to creatinine ratio, in US or SI units.
estimated creatinine clearance with actual, ideal or adjusted weight.
cardiac output and index from oxygen consumption and saturations.
ANC from the white cell count, neutrophils and bands.
insulin resistance from fasting glucose and insulin, in US or SI units.
FENa from plasma and urine sodium and creatinine: prerenal, indeterminate or tubular pattern.
water deficit in hypernatremia from sodium, weight and body water.
expected PaCO2 in metabolic acidosis, 1.5 × HCO3 + 8 ± 2.
The full 15-item stroke severity score the three items come from.
For grading subarachnoid hemorrhage.
Which published the derivation study and the 2018 review, with its current metrics.