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    NIH Stroke Scale/Score (NIHSS)

    Calculates the NIH Stroke Scale for quantifying stroke severity.

    INSTRUCTIONS

    The NIH Stroke Scale has many caveats buried within it. If your patient has prior known neurologic deficits e.g. prior weakness, hemi- or quadriplegia, blindness, etc. or is intubated, has a language barrier, etc., it becomes especially complicated. In those cases, consult the NIH Stroke Scale website. MDCalc's version is an attempt to clarify many of these confusing caveats, but cannot and should not be substituted for the official protocol.

    Rules:

    • Score what you see, not what you think.
    • Score the first response, not the best response (except Item 9 - Best Language).
    • Don’t coach.
    When to Use
    Pearls/Pitfalls
    Why Use

    The NIHSS can help physicians quantify the severity of a stroke in the acute setting.

    The National Institutes of Health Stroke Scale (NIHSS) was developed to help physicians objectively rate severity of ischemic strokes.

    • Increasing scores indicate a more severe stroke and has been shown to correlate with the size of the infarction on both CT and MRI evaluation.
    • NIHSS scores when assessed within the first 48 hours following a stroke have been shown to correlate with clinical outcomes at the 3-month and 1-year mark.
    • Patients with a total score of 4 or less generally have favorable clinical outcomes and have a high likelihood of functional independence regardless of treatment.

    Points to keep in mind:

    • Many guidelines and protocols warn that administering tPA in patients with a high NIHSS score (>22) is associated with increased risk of hemorrhagic conversion.
    • These patients, however, are also the most severely debilitated and dependent from their strokes as well.
    • Some components of the NIHSS have lower interrater reliability (i.e. facial movement, limb ataxia, neglect, level of consciousness, and dysarthria), and some may be quite limited due to altered mental status, for example.
    • A simpler, modified version of the NIHSS has been found to have greater interrater reliability with equivalent clinical performance, although it has not been as widely adopted as the original NIHSS.
    • The patient with even a large territory posterior circulation stroke syndrome may still have a low or normal NIHSS, highlighting one of its important limitations.

    There are nearly 800,000 cases of acute stroke in the United States every year, with 140,000 associated deaths (5th leading cause of death in Americans).

    The NIHSS can help physicians determine the severity of a stroke, predict clinical outcomes.

    Alert; keenly responsive
    0
    Arouses to minor stimulation
    +1
    Requires repeated stimulation to arouse
    +2
    Movements to pain
    +2
    Postures or unresponsive
    +3
    Both questions right
    0
    1 question right
    +1
    0 questions right
    +2
    Dysarthric/intubated/trauma/language barrier
    +1
    Aphasic
    +2
    Normal
    0
    Partial gaze palsy: can be overcome
    +1
    Partial gaze palsy: corrects with oculocephalic reflex
    +1
    Forced gaze palsy: cannot be overcome
    +2
    No visual loss
    0
    Partial hemianopia
    +1
    Complete hemianopia
    +2
    Patient is bilaterally blind
    +3
    Bilateral hemianopia
    +3
    Normal symmetry
    0
    Minor paralysis (flat nasolabial fold, smile asymmetry)
    +1
    Partial paralysis (lower face)
    +2
    Unilateral complete paralysis (upper/lower face)
    +3
    Bilateral complete paralysis (upper/lower face)
    +3
    No drift for 10 seconds
    0
    Drift, but doesn't hit bed
    +1
    Drift, hits bed
    +2
    Some effort against gravity
    +2
    No effort against gravity
    +3
    No movement
    +4
    Amputation/joint fusion
    0
    No drift for 10 seconds
    0
    Drift, but doesn't hit bed
    +1
    Drift, hits bed
    +2
    Some effort against gravity
    +2
    No effort against gravity
    +3
    No movement
    +4
    Amputation/joint fusion
    0
    No drift for 5 seconds
    0
    Drift, but doesn't hit bed
    +1
    Drift, hits bed
    +2
    Some effort against gravity
    +2
    No effort against gravity
    +3
    No movement
    +4
    Amputation/joint fusion
    0
    No drift for 5 seconds
    0
    Drift, but doesn't hit bed
    +1
    Drift, hits bed
    +2
    Some effort against gravity
    +2
    No effort against gravity
    +3
    No movement
    +4
    Amputation/joint fusion
    0
    No ataxia
    0
    Ataxia in 1 Limb
    +1
    Ataxia in 2 Limbs
    +2
    Does not understand
    0
    Paralyzed
    0
    Amputation/joint fusion
    0
    Normal; no sensory loss
    0
    Mild-moderate loss: less sharp/more dull
    +1
    Mild-moderate loss: can sense being touched
    +1
    Complete loss: cannot sense being touched at all
    +2
    No response and quadriplegic
    +2
    Coma/unresponsive
    +2
    Normal; no aphasia
    0
    Mild-moderate aphasia: some obvious changes, without significant limitation
    +1
    Severe aphasia: fragmentary expression, inference needed, cannot identify materials
    +2
    Mute/global aphasia: no usable speech/auditory comprehension
    +3
    Coma/unresponsive
    +3
    Normal
    0
    Mild-moderate dysarthria: slurring but can be understood
    +1
    Severe dysarthria: unintelligible slurring or out of proportion to dysphasia
    +2
    Mute/anarthric
    +2
    Intubated/unable to test
    0
    No abnormality
    0
    Visual/tactile/auditory/spatial/personal inattention
    +1
    Extinction to bilateral simultaneous stimulation
    +1
    Profound hemi-inattention (ex: does not recognize own hand)
    +2
    Extinction to >1 modality
    +2

    Result:

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    Next Steps
    Evidence
    Creator Insights
    Dr. Patrick D. Lyden

    From the Creator

    Why did you develop the NIH stroke scale?
    The NIH stroke scale was developed for use in the NINDS tPA trial [demonstrating improved outcomes in ischemic stroke for patients receiving tPA].

    What pearls, pitfalls and/or tips do you have for users of the NIH stroke scale? Are there cases in which it has been applied, interpreted, or used inappropriately?
    The point of the NIHSS is to rate groups of patients, not individuals. This is fundamental and important for users to keep in mind. A lot of the scoring rules are counterintuitive if you’re a good neurologist. It’s not true that you have to be a neurologist in order to use the NIHSS. You have to use the scoring rules. Neurologists actually do the worst. ED physicians do the best, because they follow the rules. Neurologists think they’re smarter than the scale, so they don’t follow the scoring rules. The scoring rules are there to assure reproducibility, across users of all different backgrounds, whether it’s a neuro nurse, a neurologist, or an ED physician.

    The government is now looking at outcomes based on stroke severity, so all of a sudden, this scale that we invented for research has become essential for hospitals to get reimbursed, because the more severe the stroke is, the more the reimbursement. The stroke scale has grown so far beyond its original purpose, which is fine, but you have to understand where it came from and how to use it correctly.

    What recommendations do you have for health care providers once they have applied the NIH stroke scale?
    Higher stroke scale scores indicate higher severity and poorer prognosis, but the stroke scale is NOT a guide to picking patients for tPA. tPA should be used regardless of severity.

    How does the NIHSS compare to other stroke assessments?
    At the time the NIHSS was developed, there were a dozen other scales, and they’re all roughly the same. There’s only so many ways to put numbers on the neuro exam. But the NIHSS is the most widely used, because of its use in the tPA trial, and there are training videos available. It was adopted because it happened to be the scale that was used in the tPA trial. And since the tPA trial was the first positive stroke [treatment] study, everybody started using the NIHSS. So there are over 800,000 people worldwide who have been certified with those videos. It’s not inherently better than any other scale, but it’s used, and everybody knows it.

    Why did you modify the original NIHSS?
    The modified NIHSS is more reproducible than the original. We collapsed some items, and made some items easier to score, and the data show that it’s clearly more reproducible than the original. But it has not really been adopted.

    Why not?
    I think it’s just inertia. I think if people got familiar with the modified NIHSS, they would use it, but it was never part of a successful clinical trial, so it didn’t have the cachet of the original scale.

    About the Creator

    Patrick D. Lyden, MD is chair of the Department of Neurology, Director of the Stroke Program and holds the Carmen and Louis Warschaw Chair in Neurology at Cedars-Sinai. Previously, he was a professor and vice chairman for clinical neurology at UCSD and served as the Clinical Chief of Neurology and Director of the Stroke Center at UCSD Medical Center. Dr. Lyden has published more than 200 journal articles and abstracts and edited a textbook on stroke intervention.

    To view Dr. Patrick D. Lyden's publications, visit PubMed

    Are you Dr. Patrick D. Lyden? Send us a message to review your photo and bio, and find out how to submit Creator Insights!
    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
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