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    NIH Stroke Scale/Score (NIHSS)

    Calculates the NIH Stroke Scale for quantifying stroke severity.
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    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

    Advice

    • Consult Neurology immediately (if available) for all patients presenting with ischemic stroke.
    • Evaluate whether the patient is a potential candidate to receive intravenous thrombolysis (tPA).
    • Consider further imaging including CT, CT angiography and MRI/MRA.

    Management

    In patients who present with symptoms concerning for ischemic stroke:

    • Consult Neurology.
    • Determine the onset of stroke symptoms (or time patient last felt or was observed normal).
    • Obtain a stat head CT to evaluate for hemorrhagic stroke.
    • In appropriate circumstances and in consultation with both neurology and the patient, consider IV thrombolysis for ischemic strokes in patients with no contraindications.
    • Always consider stroke mimics in the differential diagnosis, especially in cases with atypical features (age, risk factors, history, physical exam), including:
      • Recrudescence of old stroke from metabolic or infectious stress;
      • Todd’s paralysis after seizure;
      • Complex migraine;
      • Pseudoseizure, conversion disorder

    Critical Actions

    • The NIHSS is broadly predictive of clinical outcomes, but it is important to recognize that individual cases will vary and that management decisions must be made in consultation with the patient whenever possible.
    • Patients with a score of <4 are highly likely to have good clinical outcomes.
    • Whenever possible, patients with acute stroke should be transferred to a stroke center for their initial evaluation and treatment, as the holistic care (medical optimization, early initiation of PT and OT, patient and family education and discharge planning) is associated with improved clinical outcomes; some argue that most of the gains in stroke morbidity and mortality are due to these improvements in stroke care.
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