An acute stroke occurs when blood flow to a part of the brain is interrupted, causing brain cells to die. Strokes are broadly categorized as ischemic (a blood clot blocks an artery) or hemorrhagic (a blood vessel ruptures and bleeds into the brain). Ischemic strokes account for the majority of cases, and both types require immediate intervention. The swiftness of the response is the most important factor determining the patient’s outcome and long-term recovery.
The Core Standard: Defining Time Goals for Initial Assessment
Time goals for patients presenting with suspected stroke are standardized. The objective is to rapidly move the patient through triage, assessment, and imaging to confirm the diagnosis and determine treatment eligibility. The primary benchmark is the Door-to-Stroke Team goal of 15 minutes, requiring the specialized team to be at the bedside within this timeframe.
This rapid mobilization ensures the focused neurologic assessment begins immediately. The next major benchmark is the Door-to-CT initiation goal, which must be completed within 25 minutes of arrival. Since a non-contrast CT scan quickly rules out a hemorrhagic stroke, this imaging step dictates the subsequent treatment pathway.
These time intervals are linked to the Door-to-Needle (DTN) goal: the time from arrival to the start of intravenous thrombolytic medication. The target DTN is 60 minutes for most hospitals, though some centers strive for a 30-minute goal. The entire initial assessment must be completed quickly to allow for final decision-making before this deadline expires.
The Urgency of Time: Why Every Minute Counts
The strictness of these time goals is rooted in the physiological reality that “Time is Brain.” In a typical large vessel occlusion, a severe form of ischemic stroke, the brain loses a staggering number of cells every minute the artery remains blocked.
For the average patient with a large vessel occlusion, roughly 1.9 million neurons are destroyed every minute without treatment. This cellular destruction includes the loss of approximately 14 billion synapses and 12 kilometers of myelinated nerve fibers. This rate of neural circuitry loss means the ischemic brain ages about 3.6 years every hour the stroke is untreated.
The rate of tissue loss is not uniform across all patients, but the potential for rapid decline is always present. While some individuals, called “slow progressors,” may lose fewer than 35,000 neurons per minute, others, “fast progressors,” can lose more than 27 million neurons every minute. This wide variation reinforces the need to treat every stroke as a hyperacute emergency to maximize the chance of preserving brain function.
Components of the Rapid Neurologic Assessment
The rapid neurologic assessment is a focused process designed to gather critical information quickly. A primary component is obtaining the patient’s Last Known Well (LKW) time, the last moment the patient was observed acting completely normal. This time stamp is the single most important piece of information for determining eligibility for time-sensitive treatments.
The team also performs the National Institutes of Health Stroke Scale (NIHSS), a standardized 15-item scoring tool used to quantify the severity of the neurological deficit. The NIHSS assesses various functions, including:
- The patient’s level of consciousness.
- Motor strength in all four limbs.
- Visual fields.
- Language abilities.
This score provides an objective measure of stroke severity that guides treatment decisions and helps predict outcomes.
Following the initial clinical exam, the patient is moved immediately to a CT scanner. The non-contrast CT scan quickly rules out a brain hemorrhage, which excludes the patient from receiving clot-busting medication. If the non-contrast CT is negative, the team may proceed with a CT angiogram or perfusion scan to look for a large vessel occlusion and assess salvageable brain tissue.
Post-Assessment Decisions: Navigating the Treatment Window
Once the rapid assessment confirms an ischemic stroke and rules out hemorrhage, the medical team navigates the deadlines for initiating reperfusion therapies. The decision to administer intravenous thrombolytic medication is based on a narrow time window. The standard window extends up to 4.5 hours from the Last Known Well time for most eligible patients.
For patients with a large vessel occlusion, the assessment also determines eligibility for an endovascular thrombectomy, which is the mechanical removal of the clot using a catheter. This procedure has a primary treatment window of up to 6 hours from symptom onset. However, advanced imaging can identify select patients who may still benefit from thrombectomy up to 16 or even 24 hours after their symptoms began.
The speed of the initial neurologic assessment is directly linked to the patient’s ability to receive these life-saving interventions within the defined time limits. A delay in the initial Door-to-CT time reduces the remaining time available for the final treatment decision and administration of thrombolysis. Because the benefit of all stroke treatments is highly time-dependent, the system is designed to minimize every minute of delay to achieve the best possible long-term result.