Hunt-Hess Scale

Description

The Hunt-Hess Scale is a graded scale used to predict the rate of mortality based solely on the clinical features seen in a patient presenting with an aneurysmal subarachnoid haemorrhage.

GradeCharacteristicMortality Rate1,2
0Unruptured aneurysm without symptoms0%
1Asymptomatic or minimal headache with slight nuchal rigidity1-3%  
1aNo acute meningeal or brain reaction but with fixed neurological deficit1-3%
2Moderate to severe headache, nuchal rigidity, no neurological deficits other than cranial nerve palsy3-5%
3Drowsy, confused, or mild focal deficit9-19%
4Stupor, moderate to severe hemiparesis, possible early decerebrate rigidity, and vegetative disturbances23-42%  
5Deep coma, decerebrate rigidity, moribund70-77%
1. Mortality rates from Hacein-Bey & Provenzale (2011) and Lantigua et al. (2015).
2. A key feature of the Hunt and Hess Scale is the requirement to increase a patient’s grade by one level in the presence of serious systemic disease or severe vasospasm on angiography. However, this rule is inconsistently applied, thereby affecting the interpretation of study results and possibly undermining prognostic value. Furthermore, only some qualifying diseases were defined in the initial study, and the level of severity necessary for upgrading is unclear.

History of the Hunt-Hess Scale

1956 – Edmund Harry Botterell, alongside William Lougheed, John Scott, and Stuart Vandewater graded the operative risk of 23 patients with cerebral aneurysms in their study on the use of hypothermia to minimize the effects of anoxia.

1968William Hunt, alongside his resident at the time Robert Hess, modified Botterell’s classification to determine the surgical risk in 275 patients presenting with aneurysmal subarachnoid haemorrhages.

It is generally agreed that the surgical risk in intracranial aneurysm is closely related to the patient’s condition at the time of surgery, as well as to other factors such as age, associated disease, and the location of the aneurysm…we have felt that the intensity of the meningeal inflammatory reaction, the severity of neurological deficit, and the presence or absence of significant associated disease should provide the best clinical criteria for the estimate of surgical risk.

Hunt, Hess 1968

1974 – Hunt, alongside Edward J. Kosnik, modified the 1968 classification to include the new grades ‘0’ and ‘1a’. The rule of increasing the grade of severity in the presence of serious systemic disease was also added.


Associated Persons

Alternative names
  • Hunt and Kosnik Scale
  • Modified Botterell Scale

Validity and Variability

The initial 12-year and 18-year study findings revealed substantially higher mortality rates for each grade than those seen in more modern-day studies. The differences in the mortality rates may be attributed to advances in the field of surgery.

Inter-observer variability is high, with the scale having an overall κ value of ~0.48 as according to a 2011 study with 103 paired assessments. The variability is higher than the Glasgow Coma Scale and the World Federation of Neurosurgical Societies Scale.

On the contrary, a 1998 comparison of the scale to the GCS and WFNSS on 185 patients showed that the Hunt and Hess Scale has the strongest predictive power for patient outcome at 6 months, with scores on the day of operation being of more prognostic value than scores observed immediately upon admission. However, sensitivities, specificities, and predictive values of almost all scale grades, in general, were poor.


References

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Lewis is a fourth-year medical student at UWA. He is currently interested in critical care medicine

Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM with a passion for rugby; medical history; medical education; and informatics. Asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | vocortex |

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