What is the stroke management pathway, including the method to calculate the National Institutes of Health Stroke Scale (NIHSS) score?

Stroke Management Pathway and NIHSS Score Calculation

The National Institutes of Health Stroke Scale (NIHSS) is the recommended standardized assessment tool for stroke evaluation, with scores ranging from 0-42 across 11 items that assess level of consciousness, motor function, sensory function, language, and other neurological domains. 1

NIHSS Assessment Components

The NIHSS includes the following components:

Item	Assessment	Score
1A	Level of consciousness	0-3
1B	Orientation questions	0-2
1C	Response to commands	0-2
2	Gaze	0-2
3	Visual fields	0-3
4	Facial movement	0-3
5	Motor function (arm) - Left & Right	0-4 each
6	Motor function (leg) - Left & Right	0-4 each
7	Limb ataxia	0-2
8	Sensory	0-2
9	Language	0-3
10	Articulation	0-2
11	Extinction/inattention	0-2
	Total NIHSS Score	0-42

Stroke Severity Classification Based on NIHSS

• Small stroke: NIHSS <5
• Moderate stroke: NIHSS 5-15
• Large/Severe stroke: NIHSS >16 1

Prognostic Value of NIHSS Scores

• NIHSS <6: Good recovery
• NIHSS <10: 60-70% favorable outcomes at 1 year
• NIHSS >16: High probability of death or severe disability
• NIHSS >20: Only 4-16% favorable outcomes at 1 year 1

Stroke Management Pathway

1. Initial Assessment (First 60 Minutes)

• Document time of symptom onset - critical for treatment decisions

• Complete patient history:

  • Initial symptoms and progression
  • Vascular risk factors
  • Medications
  • Recent trauma or surgery
  • Family history of stroke or vascular disease
  • Alcohol or illicit drug use
  • History of seizures
  • Previous stroke or TIA 1

• Physical examination:

  • Vital signs
  • General physical exam focusing on head, heart, lungs, abdomen, and extremities
  • Cardiovascular examination (carotid bruits, arrhythmias, heart murmurs) 1

• NIHSS assessment by trained personnel

2. Immediate Management Decisions

• Thrombolytic evaluation:

  • Patients with NIHSS scores between 5-22 may benefit from thrombolytic administration
  • Evaluation for IV rtPA should be completed within 3-hour window (4.5 hours in select patients) 1
  • Note: Patients with posterior circulation strokes often present with lower NIHSS scores but may still have poor outcomes - thrombolytic treatment should not be withheld based solely on low NIHSS 2

• Endovascular therapy consideration:

  • Patients with NIHSS >22 may require additional endovascular therapies 1

3. Additional Assessments

• Functional status assessment (using Barthel Index if appropriate)
• Swallowing assessment
• Cognitive and communication deficits evaluation
• Depression screening 1

4. Ongoing Management

• DVT prophylaxis
• Intermittent pneumatic compression devices
• Early mobilization
• Antithrombotic therapy
• Carotid imaging and cardiac evaluation for stenosis requiring intervention 1

Important Considerations and Pitfalls

1. Posterior vs. Anterior Circulation Strokes:

   • Posterior circulation strokes often present with lower NIHSS scores
   • The optimal NIHSS cutoff for predicting poor outcomes is 4 for posterior circulation vs. 8 for anterior circulation strokes 2
   • Consider that a patient with posterior circulation stroke and NIHSS ≤4 may still have a 15% chance of poor outcome 2

2. 24-Hour NIHSS as Prognostic Tool:

   • The 24-hour post-thrombolysis NIHSS score (≤4) is the strongest predictor of favorable 90-day functional recovery, more so than baseline or change in NIHSS 3

3. Telemedicine Application:

   • NIHSS can be reliably administered via high-quality video teleconferencing (HQ-VTC) when bedside assessment by a stroke specialist is not immediately available 4
   • Items with highest interrater reliability include level of consciousness and motor-related questions
   • Items with lowest interrater reliability include facial palsy, ataxia, and dysarthria 4

4. Limitations of Standard NIHSS:

   • Standard NIHSS may underestimate posterior circulation stroke severity
   • Some researchers have proposed expanded versions (e-NIHSS) that better capture posterior circulation symptoms 5

By following this structured pathway and properly calculating the NIHSS score, clinicians can make timely and appropriate treatment decisions that significantly impact patient outcomes in acute stroke management.