Which stroke assessment tool should be used to evaluate a patient with suspected acute stroke?

Stroke Assessment Tool Recommendation

Use the National Institutes of Health Stroke Scale (NIHSS) or Canadian Neurological Scale (CNS) as your standardized stroke assessment tool in the emergency department and acute inpatient settings. 1

Setting-Specific Recommendations

Prehospital/EMS Setting

• EMS personnel should use validated screening tools such as:

  • Face, Arm, Speech, Time (FAST) scale
  • Cincinnati Prehospital Stroke Scale (CPSS)
  • Los Angeles Prehospital Stroke Screen (LAPSS) 2, 3

• These tools prioritize high sensitivity to avoid missing strokes, accepting lower specificity as a trade-off 4

• CPSS demonstrates the highest sensitivity (approximately 90.7%) for stroke detection in prehospital settings 5

Emergency Department and Hospital Setting

The NIHSS is the gold standard for in-hospital stroke assessment 1, 6. Here's why:

• Quantifies stroke severity objectively - allows determination of treatment eligibility for thrombolysis and endovascular therapy
• Tracks clinical changes - identifies deterioration or improvement over time
• Predicts outcomes - lower scores indicate better prognosis
• Identifies high-risk patients - helps stratify risk for complications like intracerebral hemorrhage 6

Critical implementation points:

• Use the full NIHSS, not shortened versions, to avoid false-negatives 6
• Nurses can reliably administer NIHSS with proper training, achieving high validity and reliability 6
• The Canadian Neurological Scale (CNS) is an acceptable alternative 1

In-Hospital Stroke Recognition

For patients who develop stroke while hospitalized, educate staff on rapid screening tools like FAST or Cincinnati Prehospital Stroke Score, though there is insufficient evidence to recommend one specific tool over another 7. The key is having a standardized protocol that all staff can use quickly.

Timing Considerations

Do not delay acute stroke treatment decisions while completing assessment tools 1. The neurological examination and stroke scale assessment should be rapid and should not postpone:

• Brain imaging
• Thrombolysis decision-making
• Endovascular therapy consideration

Common Pitfalls to Avoid

1. Don't use NIHSS as a screening tool in prehospital settings - it's too complex for frontline staff and dispatch personnel 7

2. Don't rely on brief cognitive screening tools alone in acute stroke - they have poor diagnostic accuracy with high specificity but low sensitivity (opposite of what's needed for triage) 8

3. Don't use shortened NIHSS versions - they increase false-negative rates, particularly in patients with lower baseline scores 6

4. Don't wait for assessment completion before activating stroke protocols - assessment should occur simultaneously with mobilizing treatment resources 3

Assessment Algorithm

Step 1: Rapid ABC assessment (airway, breathing, circulation) 1

Step 2: Apply standardized stroke scale:

• Prehospital: FAST or CPSS
• ED/Hospital: Full NIHSS or CNS

Step 3: Document specific deficits:

• Facial weakness
• Arm/leg weakness
• Speech disturbance
• Visual field defects
• Level of consciousness
• Sensory loss
• Ataxia 1

Step 4: Assess vital signs and stroke severity concurrently:

• Heart rate and rhythm
• Blood pressure
• Temperature
• Oxygen saturation
• Glucose level 1

Step 5: Proceed immediately to neuroimaging - do not delay for assessment completion 1

The evidence strongly supports NIHSS as the most validated, widely recognized, and clinically useful tool for hospital-based stroke assessment, while simpler screening tools like CPSS/FAST are appropriate for rapid prehospital identification.