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    Hunt & Hess Classification of Subarachnoid Hemorrhage

    Classifies severity of subarachnoid hemorrhage to predict mortality.
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    Patients with aSAH.

    • The Hunt-Hess classification system was originally intended to help determine the risk of surgical mortality in patients admitted with aSAH.
    • Higher grades, which are reflective of progressively higher hemorrhage severity and neurological dysfunction, are associated with higher overall mortality.
    • The scale was originally measured at admission and is typically used this way. Because it is purely clinical, the scale can change (for better or worse) during a patient’s hospital course.
    • Each grade corresponds to a specific set of clinical examination findings from 3 areas (level of arousal, reflexes, and meningeal irritation); a patient may present with a different combination of findings than that dictated by a given Hunt-Hess grade. Clinical judgment should be used to determine the final grade in these cases. (Rosen 2005)

    Points to keep in mind:

    • The scale does not apply to SAH due to trauma, arteriovenous malformations, cavernous angiomas, dural arteriovenous fistulae, cortical or sinus venous thromboses, mycotic aneurysms, or septic emboli with hemorrhagic transformation.
    • The scale is vulnerable to intra- and inter-observer variability due to the fact that it is solely based on the patient’s subjective reports and the physical examination.
    • The Hunt-Hess scale was not originally conceived to predict morbidity or degree of disability from SAH.

    This scale should NOT be used as the only clinical decision making tool in a patient with aSAH.

    This scale assumes you have a grasp of the neurological clinical examination, such as the assessment of level of consciousness, cranial nerves, and motor examination.

    • The mean case-fatality rate of aSAH is 39% (Nieuwkamp 2009) and the Hunt–Hess classification can help predict mortality in such patients.
    • The Hunt-Hess scale is widely known in the neurocritical care community.
    • The only thing needed for determining Hunt-Hess grade is the clinical examination; radiographic imaging is not necessary.
    About the Creator
    Dr. William E. Hunt
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    Advice

    • Immediate neurological and neurosurgical consultation should be obtained on patients with evidence of any SAH on imaging or lumbar puncture, irrespective of whether the SAH is likely to be aneurysmal or non-aneurysmal in nature.
    • Computed tomographic angiography (CTA) of the head is helpful to determine the presence of a lesion suitable for surgical or endovascular intervention.
    • The need for obtaining cerebrovascular imaging, such as CTA of the head or catheter angiography, should be discussed with neurological or neurosurgical consultant first.
    • Similarly, the decision to start medications that have been shown to alter outcomes in aSAH (such as nimodipine and aminocaproic acid) should be deferred to the neurological or neurosurgical consultant.

    Formula

    Selection of group of symptoms, assigned point value.

    Facts & Figures

    Criteria Value Grade Mortality
    Mild Headache, Alert and Oriented, Minimal (if any) Nuchal Rigidity 1 I 30%
    Full Nuchal Rigidity, Moderate-Severe Headache, Alert and Oriented, No Neuro Deficit (Besides CN Palsy) 2 II 40%
    Lethargy or Confusion, Mild Focal Neurological Deficits 3 III 50%
    Stuporous, More Severe Focal Deficit 4 IV 80%
    Comatose, showing signs of severe neurological impairment (ex: posturing) 5 V 90%

    Evidence Appraisal

    • Higher grade at admission was associated with higher overall mortality in Hunt and Hess’ original study of 275 aSAH patients (not all patients proceeded to aneurysm surgery, so overall mortality could be estimated).
      • The predictors of surgical mortality, i.e. the degree of meningeal irritation and the presence of neurological deficits, were based on the authors’ own opinions rather than a statistical method. (Hunt 1968)
      • Patients with severe systemic disease or severe angiographic vasospasm were “downgraded” to the next less favorable Hunt-Hess grade. (Hunt 1968)
        • The proportions of “downgraded” patients and their mortality were not fully disclosed in the primary reference. (Hunt 1968)
        • This rule is inconsistently applied in practice. (Rosen 2005)
    • In a retrospective review of 291 patients comparing 3 different SAH grading systems, the Hunt-Hess classification had the highest degree of association with mortality (OR 3.4, p<0.001). (Oshiro 1997)
      • In this study, the Hunt-Hess classification had the smallest (but still significant) degree of association with outcome (OR 2.3, P<0.001). (Oshiro 1997)
    • In a retrospective review of 185 aSAH patients that underwent aneurysm surgery, the Hunt-Hess scale had the highest correlation with outcome when compared to the World Federation of Neurological Surgeons (WFNS) and Glasgow Coma Scale (GCS) classifications, although the discriminatory performance of all three scales was poor. (Aulmann 1998)
      • This study also showed that many “poor grade” patients ultimately had good outcomes, raising the point that the Hunt-Hess scale may not be useful as the only determinant of clinical decision-making. (Aulmann 1998)
      • This study also showed that scales administered on the day of surgery were more accurate in predicting outcomes than scales administered at admission. (Aulmann 1998)
    • In a retrospective review of 1,532 aSAH patients, the Hunt-Hess scale was significantly associated with mortality (OR 1.96, 95% CI 1.69-2.29), but less strongly associated than a Glasgow Coma Scale (GCS)-based scale (OR 2.16, 95% CI 1.86-2.51). (St Julien 2008)
      • In the same study, the Hunt & Hess scale compared similarly to the GCS scale for any non-mortality outcomes. (St Julien 2008)
    • In a retrospective cohort study of 3 different SAH scales in 50 aSAH patients undergoing 103 pairwise assessments by a 57 independent clinicians per scale, the Hunt-Hess classification had a moderate interobserver agreement (k=0.48). (Degen 2011)
      • This inter-observer agreement was lower than that of the two other SAH scales. (Degen 2011)
    • In a retrospective case series of 15 patients with aSAH evaluated using the Hunt-Hess and Nishioka grading scales (8-12 observers per patient), assessment of headache had the lowest inter-rater agreement (k=0.25), followed by assessment of neurological deficit (k=0.43), then assessment of neck stiffness (k=0.51) and level of consciousness (k=0.52). (Lindsay 1983)

    Literature

    Dr. William E. Hunt

    About the Creator

    William E. Hunt, MD (d. 1999) retired in 1991 as a professor emeritus of surgery after 37 years at Ohio State College of Medicine. He received a Lifetime Achievement Award and Gold Medal from the Neurological Society of America. While best known for the Hunt-Hess classification, he also defined the Tolosa-Hunt syndrome of ophthalmoplegia, a painful paralysis of the eye muscles.

    To view Dr. William E. Hunt's publications, visit PubMed

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