Recognizing Stroke Signs
Stroke occurs when blood flow to a portion of the brain is interrupted (ischemic stroke, approximately 87% of cases) or when a blood vessel in the brain ruptures (hemorrhagic stroke, approximately 13% of cases). Rapid recognition is critical because ischemic stroke patients may be candidates for thrombolytic therapy (tPA, alteplase) if treated within 3 to 4.5 hours of symptom onset, or mechanical thrombectomy within up to 24 hours at comprehensive stroke centers. Common stroke presentations include sudden weakness or numbness of the face, arm, or leg (usually unilateral), sudden confusion or difficulty speaking or understanding speech, sudden vision changes in one or both eyes, sudden severe headache with no known cause, and sudden difficulty walking or loss of balance or coordination.
Cincinnati Prehospital Stroke Scale (CPSS)
The Cincinnati Prehospital Stroke Scale is a validated, rapid stroke screening tool consisting of three components. Any single abnormal finding has a sensitivity of approximately 66% for stroke, and the presence of all three findings increases the probability of stroke to over 85%. The assessment takes less than one minute to perform and should be conducted on any patient presenting with signs or symptoms suggestive of stroke. Each component tests a different area of brain function and helps confirm the clinical suspicion of acute cerebrovascular event.
Facial Droop
Ask the patient to show their teeth or smile broadly. Normal: both sides of the face move equally and symmetrically. Abnormal: one side of the face does not move as well as the other side, the smile is uneven, or one side of the face appears to droop or sag. Note which side is affected, as this helps localize the stroke (the facial droop typically occurs on the opposite side of the brain lesion). Subtle droop may be easier to identify when the patient attempts to smile or show teeth rather than at rest. Compare the nasolabial folds for symmetry as well. Document the specific findings and which side is affected.
Arm Drift
Ask the patient to close their eyes and hold both arms straight out in front of them, palms up, for 10 seconds. Normal: both arms remain in the same position, or both arms move equally. Abnormal: one arm drifts downward compared to the other, or one arm does not move at all. The affected arm may also pronate (rotate palm downward) as it drifts. If the patient cannot extend their arms due to injury or other limitation, compare grip strength bilaterally as an alternative assessment. Document which arm is affected and the degree of drift or weakness. Unilateral arm weakness or drift is a strong indicator of contralateral hemispheric stroke.
Speech
Ask the patient to repeat a simple phrase such as "You can't teach an old dog new tricks" or "The sky is blue in Cincinnati." Normal: the patient uses correct words without slurring. Abnormal findings include slurred speech (dysarthria), use of wrong or garbled words (aphasia), or the inability to speak at all. Assess both the ability to produce speech (expressive function) and the ability to understand commands (receptive function). Patients with expressive aphasia may understand you but cannot form words correctly. Patients with receptive aphasia may produce fluent-sounding speech that makes no sense and may not follow commands. Document the specific speech abnormality observed. Also note any difficulty swallowing, as this may indicate dysphagia and increases the risk of aspiration.
Last Known Well Time
Establishing the last known well time is one of the most critical pieces of information for stroke patients. This is defined as the last time the patient was observed to be at their normal neurological baseline, NOT the time when symptoms were first noticed. For example, if a patient goes to sleep at 10:00 PM and wakes with stroke symptoms at 6:00 AM, the last known well time is 10:00 PM (8 hours ago), not 6:00 AM. Interview the patient, family members, bystanders, and caregivers to establish the most accurate timeline. If the patient was last seen normal by phone or video call, that counts. Document this time precisely and communicate it clearly to the receiving facility. The time window for tPA administration is 3 to 4.5 hours from last known well, and the window for mechanical thrombectomy may extend to 24 hours at specialized centers with advanced imaging capabilities.
Transport Decisions
Patients with a positive stroke screen require rapid transport to the nearest appropriate stroke facility. Primary Stroke Centers (PSC) can administer tPA and provide initial stroke management. Comprehensive Stroke Centers (CSC) can also perform mechanical thrombectomy and neurosurgical interventions. If your local protocol includes stroke severity scales such as LAMS (Los Angeles Motor Scale) or RACE (Rapid Arterial oCclusion Evaluation), use these to identify potential large vessel occlusion (LVO) strokes that benefit from direct transport to a CSC even if a PSC is closer. Provide a prehospital stroke alert to the receiving facility to activate the stroke team before arrival, reducing door-to-treatment time. During transport, maintain the patient's head of bed elevated at 30 degrees if possible, protect the airway (stroke patients are at high aspiration risk), monitor blood glucose (hypoglycemia can mimic stroke), and perform serial neurological assessments to document progression or improvement. Do not administer aspirin to a suspected stroke patient in the field, as hemorrhagic stroke must be ruled out by CT scan first.
Additional Stroke Assessment Tools
While the Cincinnati scale is the most commonly tested prehospital stroke screen, be aware of other tools. The BE-FAST mnemonic expands on the traditional FAST by adding Balance (sudden loss of balance or coordination) and Eyes (sudden vision changes) to Face, Arms, Speech, and Time. The Los Angeles Prehospital Stroke Screen (LAPSS) includes additional criteria such as age, history of seizures, symptom duration, blood glucose, and unilateral findings. The NIH Stroke Scale (NIHSS) is used in the hospital setting for more detailed assessment and scoring, but familiarity with its components can improve your overall stroke assessment skills. Regardless of which tool you use, the key principles remain the same: recognize stroke signs rapidly, establish last known well time, provide a stroke alert, and transport without delay to the appropriate stroke facility.