Time is Brain: Why Stroke Assessment Matters
Stroke is the fifth leading cause of death in the United States and a leading cause of long-term disability. During an ischemic stroke, approximately 1.9 million neurons die every minute that treatment is delayed. The phrase "time is brain" captures the urgency of stroke recognition and rapid transport. EMS providers who can quickly identify stroke, determine symptom onset time, and transport to an appropriate stroke center save brain tissue and improve patient outcomes.
Strokes are classified as ischemic (caused by a blood clot blocking cerebral blood flow, accounting for about 87% of strokes) or hemorrhagic (caused by bleeding in the brain). While prehospital providers cannot distinguish between these types with certainty, the initial assessment and transport approach is the same: rapid recognition and transport to a stroke-capable facility.
Prehospital Stroke Screening Tools
Cincinnati Prehospital Stroke Scale (CPSS)
The CPSS is the most widely used prehospital stroke screening tool. It tests three components:
- Facial Droop: Ask the patient to smile or show their teeth. Normal: both sides of the face move equally. Abnormal: one side of the face does not move as well as the other.
- Arm Drift: Ask the patient to close their eyes and hold both arms straight out for 10 seconds. Normal: both arms stay in position. Abnormal: one arm drifts downward compared to the other.
- Speech: Ask the patient to repeat "You can't teach an old dog new tricks." Normal: patient repeats clearly and correctly. Abnormal: slurred speech, wrong words, or inability to speak.
Any one abnormal finding on the CPSS gives a 72% probability of stroke. All three abnormal findings give greater than 85% probability.
BE-FAST
The expanded BE-FAST mnemonic adds Balance and Eyes to the traditional FAST assessment: Balance (sudden loss of balance or coordination), Eyes (sudden vision loss or double vision), Face (facial droop), Arms (arm weakness), Speech (speech difficulty), Time (time to call 911 and note when symptoms started). The addition of balance and vision findings captures posterior circulation strokes that the CPSS may miss.
Establishing Symptom Onset Time
The most critical piece of information for stroke treatment is when symptoms began. The window for IV thrombolytic therapy (tPA) is up to 4.5 hours from symptom onset, and the window for mechanical thrombectomy (clot retrieval) extends to 24 hours for select patients. Ask the patient, family, or bystanders: "When was the patient last seen normal?" If the patient woke up with symptoms, the "last known well" time is when they were last seen without symptoms (often the night before), not when they woke up.
Transport Decisions
Transport stroke patients to the nearest appropriate stroke center, which may not be the closest hospital. Primary Stroke Centers can administer tPA; Comprehensive Stroke Centers can also perform mechanical thrombectomy and manage hemorrhagic strokes. For patients with large vessel occlusion (LVO) findings (severe deficits, LAMS score of 4 or higher), bypassing a Primary Stroke Center for a Comprehensive Stroke Center may be appropriate if the additional transport time is within protocol limits. Prenotify the receiving hospital with a stroke alert, including the last known well time, CPSS findings, blood glucose level, and ETA.