The Cincinnati Prehospital Stroke Scale (CPSS) is a rapid assessment tool used by emergency medical services (EMS) personnel to quickly identify a potential stroke in the field. Developed in 1997, the CPSS provides a simplified way for paramedics and emergency medical technicians to screen for the most common signs of a stroke. The scale focuses on three specific physical findings indicative of acute neurological impairment. A positive finding in just one of the three tests suggests a high probability that the patient is experiencing a stroke, allowing first responders to communicate time-sensitive information to the receiving hospital.
Why Rapid Prehospital Assessment is Essential
The urgency of stroke care is often summarized by the phrase “Time is Brain,” as approximately 1.9 million brain cells are lost every minute a stroke goes untreated. A stroke, caused by a disruption of blood flow to the brain, results in rapid and irreversible damage to nervous tissue. Patients who receive treatment quickly experience improved outcomes and a reduced risk of long-term disability. This narrow window of time is important for administering thrombolytics, which restore blood flow and minimize brain damage. The prehospital environment is the first opportunity to initiate the stroke chain of survival, making a fast and accurate assessment like the CPSS necessary.
The Three Key Components of the Scale
The CPSS assesses three distinct neurological functions: facial droop, arm drift, and abnormal speech. When abnormal, these components are highly suggestive of a stroke. A single positive finding indicates a 72% probability of an ischemic stroke, and this probability increases to over 85% if all three findings are present.
Facial Droop
Facial droop is assessed by asking the person to smile or show their teeth. The responder observes if one side of the face moves less than the other or appears to droop. An abnormal finding occurs when the movement on one side of the face is clearly unequal.
Arm Drift
Arm drift evaluates for unilateral weakness. The person is asked to hold both arms straight out, palms up, and close their eyes for about 10 seconds. An abnormal result is recorded if one arm fails to raise or drifts downward compared to the other. This finding indicates a motor deficit, a common sign of brain injury on the opposite side of the body.
Abnormal Speech
This component evaluates speech by having the patient repeat a simple, familiar phrase, such as “You can’t teach an old dog new tricks.” The responder listens for slurred speech, the use of incorrect words, or an inability to speak. Any of these findings are considered abnormal, signaling a possible language center impairment.
What Happens After a Positive Score
A positive CPSS result triggers a cascade of time-sensitive protocols within the EMS system and the hospital. First responders immediately notify the receiving facility, providing a “Stroke Alert” to activate the hospital’s specialized stroke team before the patient arrives. This pre-arrival notification allows the hospital to prepare the computed tomography (CT) scanner and have specialists ready, significantly reducing the time to diagnosis and treatment.
Transport decisions are also affected by a positive CPSS score. EMS may bypass the closest hospital if it is not a certified Stroke Center. Patients are preferentially transported to a Comprehensive Stroke Center or a Thrombectomy-capable Stroke Center, which are equipped for advanced treatments like mechanical thrombectomy. The goal is to limit the scene time to a minimum, often less than 15 minutes, ensuring the patient reaches definitive care within the narrow window for life-saving interventions.