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    Cincinnati Prehospital Stroke Severity Scale (CP-SSS)

    Predicts large vessel occlusion (LVO) and severe stroke in patients with stroke symptoms.
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    INSTRUCTIONS

    Use in a hospital setting in patients with signs and symptoms of acute ischemic stroke.

    When to Use
    Pearls/Pitfalls
    Why Use

    Patients in a hospital setting with signs and symptoms of acute ischemic stroke.

    • May be used to determine both severity of stroke, as quantified by NIHSS ≥15, and presence of LVO.
    • Accuracy at detecting LVO or severe stroke has not been evaluated when administered by EMS providers.
    • Acute stroke caused by LVO may be amenable to additional treatment beyond intravenous tissue plasminogen activator (tPA), including mechanical thrombectomy.
    • Benefit from mechanical thrombectomy in acute stroke from LVO is time-dependent, so early recognition may help timely mobilization of neurosurgical or endovascular care teams.
    • Based on three items from the NIH Stroke Scale (NIHSS), which is familiar to and easily administered by many emergency physicians and neurologists, as opposed to the LAMS, which is made up of three clinical items, one of which (grip strength) is not included in the NIHSS, and the RACE Scale, which includes more (six) clinical items.

    Result:

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    Next Steps
    Evidence
    Creator Insights

    Advice

    • Neurological consultation should be obtained immediately in suspected acute ischemic stroke.
    • Acute ischemic stroke is a neurological emergency that is amenable to time-sensitive treatments (e.g. tPA, mechanical thrombectomy) if certain clinical conditions are met.
    • Should not be used as a substitute for clinical judgment, and is intended for use as an adjunct to medical decision-making.

    Management

    • In cases of suspected acute ischemic stroke from LVO, the following is recommended:
      • STAT neurological consultation.
      • STAT CT head without contrast.
      • STAT CTA head and neck with contrast.
      • STAT laboratory testing (complete blood count, coagulation profile, basic metabolic panel, type and screen, troponin-I).

    Critical Actions

    • Intravenous tissue plasminogen activator (IV tPA) is the standard-of-care treatment for adult patients presenting with acute ischemic stroke within 4.5 hours of symptom onset if no exclusion criteria are met, irrespective of whether LVO is the cause or not.
    • Endovascular (mechanical) thrombectomy is the standard-of-care treatment for selected adult patients presenting with acute ischemic stroke due to LVO.
    • A patient’s appropriateness for endovascular intervention depends on multiple factors, such as time since onset of symptoms, neuroimaging, baseline functional status, and others.
    • Appropriateness for intravenous thrombolysis or mechanical thrombectomy should be determined by neurological/neurosurgical consultant whenever available.

    Formula

    Addition of the selected points:

    Conjugate gaze deviation

    2 points

    Incorrectly answers ≥1 of two “level of consciousness” questions on NIHSS (age or current month) AND does not follow ≥1 of the two commands (close eyes, open/close hand)*

    1 point

    Cannot hold arm (either or both) up for 10 seconds before arm(s) falls to bed**

    1 point


    *i.e., ≥1 on the NIHSS item for Level of Consciousness 1b and 1c.

    **i.e., ≥2 on the NIHSS item for Motor Arm.

    Facts & Figures

    Interpretation:

    CP-SSS

    LVO and NIHSS

    0–1

    LVO and NIHSS ≥15 less likely

    2–4

    LVO and NIHSS ≥15 likely

    Evidence Appraisal

    Katz et al derived the CP-SSS in 2015 by incorporating NIHSS components into a classification and regression tree (CART) model to predict severe stroke (defined by NIHSS ≥15; primary outcome) and identify LVO (secondary outcome). The derivation population consisted of patients randomized to treatment with tPA or placebo for acute stroke within 3 hours of onset (n = 624). This study also contained an internal validation of the CP-SSS using a population from the Interventional Management of Stroke (IMS) trial (n = 650, of which 303 had LVO).

    The AUC was 0.89 for detecting severe stroke and a CP-SSS cut-point of ≥2 had a sensitivity of 89% and specificity of 78% for identifying patients with severe stroke. In the internal validation study, the AUC, sensitivity, and specificity were similar to that of the derivation population for detecting severe stroke. The AUC was 0.67 for detecting patients with LVO, and CP-SSS ≥2 had a sensitivity of 83% and specificity of 40% for identifying patients with LVO.

    The CP-SSS was externally validated in a population of stroke patients from a single academic stroke center, using LVO as a primary outcome and severe stroke as a secondary outcome (n = 664). The AUC was 0.85 (95%CI 0.81-0.90) for predicting LVO, and a CP-SSS of ≥2 was 70.0% sensitive and 86.8% specific for predicting LVO. The AUC was 0.95 (95%CI 0.92-0.97) for detecting severe stroke, and a CP-SSS of ≥2 was 87.2% sensitive and 94.3% specific for identifying severe stroke.

    Outcome

    CP-SSS cut-point

    Sensitivity

    Specificity

    LR+

    LR-

    LVO

    ≥1

    82.5%

    82.5%

    4.7

    0.2

    ≥2

    58.8%

    90.2%

    6.0

    0.5

    ≥3

    50.0%

    93.7%

    7.9

    0.5

    4

    25.0%

    96.2%

    6.6

    0.8

    NIHSS ≥15

    ≥1

    90.6%

    88.7%

    8.0

    0.1

    ≥2

    64.1%

    94.7%

    12.1

    0.4

    ≥3

    59.8%

    98.7%

    46.8

    0.4

    4

    35.0%

    99.8%

    191.7

    0.6

    Dr. Brian S. Katz

    About the Creator

    Brian S. Katz, MD, is a vascular neurologist at OhioHealth Riverside Methodist Hospital in Columbus, Ohio. He has authored or co-authored several studies in stroke neurology. Dr. Katz completed residency at Mayo Clinic and fellowship at the University of Cincinnati.

    To view Dr. Brian S. Katz's publications, visit PubMed

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