Hunt and Hess Grade Interpreter
Hunt and Hess Grade Interpreter
Grade aneurysmal subarachnoid haemorrhage I to V on the 1968 clinical descriptors, including the rule that serious systemic disease moves the patient a grade. Mortality by grade is from a 1,200-patient cohort, and rater agreement is only moderate.
Hunt and Hess grade
Clinical state to grade I to VSevere headache and neck stiffness, drowsy but rousable, no limb weakness, no significant comorbidity
The grades
Serious systemic disease or severe angiographic vasospasm moves the patient one grade less favourable, to a maximum of V
- the grade II exception and the 1974 additions
- a cranial nerve palsy does not take a patient out of grade II; every other focal deficit moves them to grade III or beyond. Hunt and Kosnik’s 1974 revision added the systemic-disease modifier, plus a grade 0 for an unruptured asymptomatic aneurysm and a grade 1a for a fixed deficit without acute meningeal reaction. Neither of those two is in wide use or appears in the cohort figures here, so this page implements grades I to V
- mortality by grade
- from Lantigua and colleagues’ 1,200-patient consecutive Columbia University cohort, July 1996 to January 2009: 3 per cent for grades 1–2, 9 per cent for grade 3, 24 per cent for grade 4 and 71 per cent for grade 5, against 18 per cent overall. Half the patients who died were do-not-resuscitate at the time of death
- rater agreement
- moderate. Degen and colleagues measured it across 103 paired assessments, and the two independent reproductions of that work we could read give the kappa as 0.42 and 0.48 — both printed here because they disagree. The disagreement concentrates at the II/III and III/IV boundaries
- which scale to use
- the 2023 AHA/ASA guideline recommends either this grade or the WFNS grade at Class 1, Level B-NR, “to determine initial clinical severity and predict outcome”, and names no preference. They are not convertible, so record which scale a grade came from
Worked example
Severe headache and neck stiffness, drowsy but rousable, no limb weakness, no significant comorbidity
Drowsiness takes the patient past grade II, which allows headache and neck stiffness but no alteration of consciousness
No hemiparesis and no stupor, so not grade IV: the clinical state is grade III and the systemic-disease modifier does not apply
In Lantigua’s 1,200-patient Columbia cohort, in-hospital mortality at grade 3 was 9 per cent, against 24 per cent at grade 4
Now add poorly controlled diabetes and severe arteriosclerosis. Hunt and Kosnik’s modifier moves the patient to grade IV — the same neurology, a grade worse, and a cohort mortality figure nearly three times higher. That is the weight carried by a rule applied inconsistently between units
The same patient on the WFNS grade needs a number rather than the word “drowsy”: at GCS 14 without a motor deficit they are WFNS grade II, and at GCS 12 they are WFNS grade IV
The five grades
| Grade | Clinical state | In-hospital mortality, Columbia cohort n = 1,200 |
|---|---|---|
| I | Asymptomatic, or minimal headache and slight nuchal rigidity | 3% (grades 1 and 2 reported together) |
| II | Moderate to severe headache, nuchal rigidity, no deficit other than a cranial nerve palsy | 3% (grades 1 and 2 reported together) |
| III | Drowsy or confused, or a mild focal deficit | 9% |
| IV | Stupor, moderate to severe hemiparesis, early decerebrate rigidity, vegetative disturbance | 24% |
| V | Deep coma, decerebrate rigidity, moribund appearance | 71% |
Hunt and Hess against WFNS, on the same patient
| Finding | Hunt and Hess | WFNS |
|---|---|---|
| Alert, isolated third nerve palsy | Grade II — a cranial nerve palsy is allowed | Grade I — a cranial nerve palsy is not a motor deficit |
| Alert, mild arm weakness | Grade III | Not a grade the published scale defines |
| Drowsy, GCS 14, no weakness | Grade III | Grade II |
| GCS 10, hemiparesis | Grade IV | Grade IV |
| GCS 4, extending | Grade V | Grade V |
| Any of the above with serious systemic disease | One grade less favourable, to a maximum of V | No modifier — the grade does not change |
A 1968 measure of operative timing, still carrying prognostic weight
Hunt and Hess published their five grades in 1968 in a paper titled Surgical risk as related to time of intervention in the repair of intracranial aneurysms. The question it answered was when to operate on a ruptured aneurysm, in an era before early clipping, endovascular coiling and nimodipine. The grades describe a clinical gestalt — headache and neck stiffness, drowsiness, stupor, coma — and the scale has survived six decades because those descriptors are short, need no investigations, and are recorded in every unit in the world.
Two features repay care. The grade II exception: a cranial nerve palsy does not move a patient out of grade II, because a third nerve palsy from a posterior communicating artery aneurysm localises the aneurysm rather than describing injured brain. Any other focal deficit does. And the modifier Hunt and Kosnik added in 1974 — serious systemic disease, or severe vasospasm on arteriography, places the patient in the next less favourable category. That rule is applied inconsistently between units and within them, it is a documented source of rater disagreement, and it cannot push a patient past grade V, so at the top of the scale comorbidity becomes invisible.
The outcome figures worth quoting are modern. In Lantigua and colleagues’ consecutive series of 1,200 patients admitted to Columbia University between July 1996 and January 2009, in-hospital mortality was 18 per cent overall: 3 per cent for grades 1 and 2 together, 9 per cent for grade 3, 24 per cent for grade 4 and 71 per cent for grade 5. The original 1968 and 1974 series reported considerably higher mortality at every grade, so an older textbook number and a current one are not comparable — and that analysis records half the patients who died as do-not-resuscitate at the time of death, which means the grade contributed to the outcome it predicts. Rater agreement is the best-documented weakness: Degen and colleagues measured it across 103 paired assessments, and the two independent summaries we could read give the kappa as 0.42 and 0.48. Both are printed because they disagree, and either way the agreement is moderate, concentrated where “drowsy” and “mild focal deficit” have to be judged. That is the problem the WFNS grade was written to solve. Every threshold here comes from a named cohort, and cohorts differ in case mix, era and treatment; where your unit’s protocol differs, it takes precedence.
Frequently asked questions
What are the Hunt and Hess grades?
Grade I is asymptomatic or minimal headache with slight neck stiffness; II is moderate to severe headache and neck stiffness with no deficit other than a cranial nerve palsy; III is drowsiness, confusion or a mild focal deficit; IV is stupor with moderate to severe hemiparesis; V is deep coma with decerebrate rigidity and a moribund appearance.
Does a third nerve palsy make a patient Hunt and Hess grade III?
No. Grade II explicitly allows a cranial nerve palsy, because a third nerve palsy from a posterior communicating artery aneurysm reflects the aneurysm pressing on the nerve rather than injury to the brain. Every other focal deficit does move the patient to grade III or beyond.
What does the systemic-disease rule do?
Hunt and Kosnik’s 1974 revision placed a patient with serious systemic disease, or severe vasospasm on arteriography, in the next less favourable category. It cannot move a patient past grade V, and it is applied inconsistently between units.
What is the mortality for each Hunt and Hess grade?
In a consecutive Columbia University cohort of 1,200 patients (1996 to 2009), in-hospital mortality was 3 per cent for grades 1 and 2 together, 9 per cent for grade 3, 24 per cent for grade 4 and 71 per cent for grade 5, with 18 per cent overall. Half the patients who died were do-not-resuscitate at the time of death.
Should I use Hunt and Hess or the WFNS grade?
The 2023 AHA/ASA guideline recommends either, at Class 1 and Level B-NR, and expresses no preference. WFNS replaces the subjective descriptors with a Glasgow Coma Scale range and is the more reproducible. What matters is recording which scale a grade came from.
Related calculators
References
- Hoh BL, Ko NU, Amin-Hanjani S, et al. 2023 guideline for the management of patients with aneurysmal subarachnoid hemorrhage. Stroke. 2023;54(7):e314–e370.
- Lantigua H, Ortega-Gutierrez S, Schmidt JM, et al. Subarachnoid hemorrhage: who dies, and why? Crit Care. 2015;19(1):309.
- Hunt-Hess scale. Life in the Fast Lane, litfl.com (accessed 7 October 2026), citing Degen LA, Dorhout Mees SM, Algra A, Rinkel GJE, Stroke 2011;42(6):1546–1549 for interobserver agreement.
- Grading of subarachnoid haemorrhage severity. Deranged Physiology, neurological intensive care chapter 172, derangedphysiology.com (accessed 7 October 2026).
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/