Quantifying Stroke Severity with the NIH Score - AHA Guidelines Informed

The NIH Stroke Scale quantitatively measures neurological deficits caused by stroke. This article outlines the scale's purpose, components, scoring, interpretation, and benefits according to AHA guidelines for informing treatment decisions and predicting outcomes. Read on to understand use of this ubiquitous tool in acute stroke care.

Overview of the NIH Stroke Scale

The NIH Stroke Scale (NIHSS) is a tool used by healthcare providers to objectively quantify the impairment caused by a stroke. It was developed in the 1980s by neurologists at the National Institutes of Health (NIH). The NIHSS allows providers to systematically document neurological deficits in stroke patients. Scores correlate with stroke severity and can help guide acute stroke treatment and predict patient outcomes.

Purpose of the Scale

The main goals of the NIHSS are to:

- Provide a quantitative measure of stroke-related neurological deficit

- Track recovery of neurological function

- Predict patient outcomes and determine appropriate treatments

Components of the Scale

The NIHSS evaluates the effect of acute stroke on a patient’s neurological function. The scale assesses 11 categories including:

- Level of consciousness - Gaze - Visual fields - Facial movement - Motor function and coordination

Scoring the Scale

Each item on the scale is scored with a specific grading system. The individual scores are then summed to calculate a patient's total NIHSS score. Scores range from 0 to 42, with higher values reflecting more severe neurological deficits.

Interpretation of Scores

NIHSS scores indicate the severity of stroke impairment:

- 0: No stroke symptoms

- 1-4: Minor stroke

- 5-15: Moderate stroke

- 16-20: Moderate to severe stroke

- 21+: Severe stroke

Advantages of the NIHSS

Benefits of using the NIHSS include:

- Rapid assessment early in stroke care

- Quantitative measure of deficits

- Facilitates communication across treatment team

- Helps predict prognosis and guide treatment decisions

The NIHSS and AHA Guidelines

The American Heart Association/American Stroke Association guidelines strongly recommend using the NIHSS in acute stroke patient evaluation. The scale provides critical data that informs appropriate use of intravenous thrombolysis and endovascular therapies for ischemic stroke per AHA/ASA evidence-based treatment guidelines.

Several facts about nih stroke scale aha

Acute Stroke

The NIH Stroke Scale is frequently used to evaluate patients who have suffered an acute ischemic or hemorrhagic stroke. It helps quantify the initial severity of stroke symptoms in those first 24 hours after onset. The scale can help guide acute treatment decisions.

Neurological Deficits

The NIH Stroke Scale is an impairment measurement tool that systematically assesses degrees of neurological deficits across different domains like motor function, sensation, coordination, vision, etc. Deficits reflect areas of brain damaged by stroke.

Ischemic Stroke

Most strokes are ischemic, caused by an arterial clot cutting off blood flow to brain tissue. The NIHSS measures deficits resulting from the area of brain ischemia. Scores help determine eligibility and response to IV thrombolysis or endovascular treatment per AHA guidelines.

Infarct Volume

Higher NIH Stroke Scale scores correlate with larger brain infarct volumes measured on neuroimaging. Serial scores can reflect evolution or change in infarct size over time.

Intracerebral Hemorrhage

While less common than ischemic stroke, the scale can also be used for initial assessment of hemorrhagic strokes caused by ruptured blood vessels in the brain resulting in localized bleeding and tissue damage.

Modified Rankin Scale

The Modified Rankin Scale measures disability and dependence in daily activities. Baseline NIHSS correlates with 90-day scores on this scale in describing lasting morbidity and outcomes post-stroke.

Glasgow Coma Scale

While the NIHSS focuses on stroke-specific deficits, the GCS provides a basic assessment of consciousness and arousal that complements information from the stroke scale.

Barthel Index

This validated scale evaluates a patient's performance ability in activities of daily living. Like the Rankin Scale, baseline NIHSS correlates with follow-up Barthel Index as a functional outcome measure.

Thrombolysis

For qualifying ischemic stroke patients, intravenous thrombolysis using tPA can dissolve artery-occluding clots. Initial NIHSS scores help determine tPA eligibility and subsequent score drops indicate treatment response.

Endovascular Therapy

In certain major ischemic strokes, endovascular procedures can extract clots mechanically. As with IV tPA, baseline NIHSS and post-treatment shifts inform urgent treatment decisions around this therapy.

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