What is the Cincinnati Prehospital Stroke Scale (CPSS)?
The Cincinnati Prehospital Stroke Scale (CPSS) is a rapid, 3-item physical examination tool designed for prehospital stroke identification that assesses facial droop, arm drift, and speech abnormalities—with any single abnormality indicating 72% probability of stroke. 1
Components of the CPSS
The CPSS evaluates three specific physical findings 1:
1. Facial Droop
- Test: Have the patient show their teeth or smile
- Normal: Both sides of face move equally
- Abnormal: One side of face does not move as well as the other side
2. Arm Drift
- Test: Patient closes eyes and holds both arms straight out for 10 seconds
- Normal: Both arms move the same, or both arms do not move at all
- Abnormal: One arm does not move or one arm drifts down compared with the other
3. Abnormal Speech
- Test: Have the patient say "you can't teach an old dog new tricks"
- Normal: Patient uses correct words with no slurring
- Abnormal: Patient slurs words, uses the wrong words, or is unable to speak
Performance Characteristics
The CPSS demonstrates strong diagnostic accuracy when administered by prehospital providers, with sensitivity of 59% and specificity of 89% for all strokes 1. However, performance improves substantially for anterior circulation strokes, reaching 88% sensitivity 2. The scale shows excellent reproducibility among prehospital personnel (intraclass correlation coefficient 0.89) 2.
More recent validation studies confirm its utility: sensitivity of 81% with positive predictive value of 100% in combined assessment 3, and 88.5% sensitivity in urban emergency department settings 4.
Clinical Application
EMS leaders should implement the CPSS as a validated screening tool for rapid stroke identification 5. The American Heart Association recommends that all paramedics and EMT-basics receive training in stroke recognition using validated tools such as the CPSS (Class I, Level of Evidence B) 1.
The scale is based entirely on physical examination—no historical information or laboratory values are required 1. This makes it particularly valuable in time-sensitive prehospital settings where rapid assessment is critical.
Key Advantages
- Simplicity: Can be completed in under 1 minute
- No equipment needed: Pure physical examination
- Layperson-capable: Studies demonstrate that untrained adults can accurately administer the CPSS over the telephone with 94% sensitivity and 83% specificity when directed by dispatchers 6, 7
- Improved outcomes: Paramedic sensitivity for stroke identification increases from 61-66% with standard training to 86-97% after training with stroke assessment tools like CPSS 1
Important Caveats
The CPSS is NOT validated for pediatric populations and should not be used as the sole tool to identify stroke in children 8. Adult stroke scales miss the broad, nonspecific presentations common in pediatric stroke.
While the Los Angeles Prehospital Stroke Screen (LAPSS) demonstrates higher sensitivity (93%) and specificity (97%) 1, it requires ruling out other causes of altered consciousness and is more complex to administer. The CPSS remains the preferred tool when simplicity and speed are paramount, particularly for layperson or basic EMS provider use.
Integration into Stroke Systems of Care
When any one of the three CPSS findings is abnormal, immediate EMS activation and transport to an appropriate stroke center is indicated 5, 8. The 2019 AHA recommendations specify that standardized stroke screening tools like CPSS should be used by all EMS providers to ensure rapid identification and appropriate triage 5.
For severity-based triage, CPSS score of 3 (all three components abnormal) strongly predicts large vessel occlusion (OR 8.5) and warrants consideration of direct transport to comprehensive stroke centers when bypass time is <15 minutes 9.