Hunt and Hess Grading Scale for Aneurysmal Subarachnoid Hemorrhage
The Hunt and Hess (HH) grading scale divides patients with aneurysmal subarachnoid hemorrhage into 5 progressively severe grades based on clinical presentation, and is recommended by the American Heart Association/American Stroke Association for determining initial clinical severity and predicting outcomes. 1
The Five Hunt and Hess Grades
The HH scale stratifies patients into the following categories of increasing severity 2:
- Grade I: Asymptomatic or minimal headache with slight nuchal rigidity
- Grade II: Moderate to severe headache, nuchal rigidity, but no neurological deficit other than cranial nerve palsy
- Grade III: Drowsiness, confusion, or mild focal neurological deficit
- Grade IV: Stupor, moderate to severe hemiparesis, possible early decerebrate rigidity and vegetative disturbances
- Grade V: Deep coma, decerebrate rigidity, moribund appearance
Clinical Significance and Prognostic Value
The HH grade directly correlates with patient outcomes and guides treatment decisions. 1 The scale effectively separates patients into low-grade (I-II) and high-grade (III-V) categories, with dramatically different prognoses 2, 3.
Outcome Expectations by Grade
- Low-grade patients (HH I-II): Approximately 60-70% achieve good physical outcomes without severe cognitive dysfunction when treated appropriately 4
- High-grade patients (HH IV-V): Only 39-40% achieve favorable outcomes at 12 months even with treatment 1, though outcomes improve significantly if patients show neurological improvement by 48 hours 5
Treatment Implications
The HH grade influences surgical timing and approach 2, 6:
- HH I-II patients: Benefit from early surgery (within 72 hours) 6
- HH III-V patients: Historically achieved better results with delayed surgery, though modern management in specialized neurological ICUs has improved outcomes with early aneurysm securing 1
Important Clinical Caveats
Delayed reassessment at 48 hours post-admission significantly improves prognostication, particularly for HH grade V patients. 5 Initial moribund examination does not always predict final outcome—patients who improve from HH V to HH IV or lower by 48 hours have substantially better survival rates 5.
The presence of intracerebral hemorrhage on imaging dramatically worsens prognosis regardless of initial HH grade. 7 All patients with middle cerebral artery aneurysms and intracerebral hematoma in one series either died or remained vegetative despite surgical intervention 7.
Age significantly modifies outcomes within each HH grade. 1 While 82% of younger patients achieved functional independence at 6 years, only 42% of patients >65 years reached this milestone, though treatment remains reasonable in elderly patients after appropriate discussion 1.