Hunt and Hess Scale Calculator

Aneurysmal subarachnoid hemorrhage - bleeding into the space between the arachnoid and pia mater, usually from rupture of a saccular aneurysm on the circle of Willis - affects roughly 9 people per 100,000 each year. The Hunt and Hess scale compresses the bedside neurological examination into one ordinal grade from I to V, because depth of impaired consciousness after the ictus tracks intracranial pressure, blood volume, and global ischemia better than any single imaging finding. Grade I is an asymptomatic patient or minimal headache with slight nuchal rigidity. Grade II adds severe headache and meningismus but still permits an isolated cranial nerve palsy, classically a third nerve palsy from a posterior communicating artery aneurysm. Grade III introduces drowsiness, confusion, or mild focal deficit; Grade IV means stupor with hemiparesis and early decerebrate posturing; Grade V is deep coma. Grades I and II are treated as good-risk patients for securing the aneurysm within 72 hours, while Grades IV and V carry historical mortality near 80 to 90 percent. Agreement between observers is only moderate because the verbal anchors overlap, and the grade ignores age, aneurysm size and location, and the cisternal blood burden that drives vasospasm. It also cannot be applied cleanly to a sedated or intubated patient. Grade is dynamic and should be reassessed after ventriculostomy for hydrocephalus and blood pressure control, since a patient improving from IV to III may become a surgical candidate.

William E. Hunt and Robert M. Hess, neurosurgeons at Ohio State University, published the scale in the Journal of Neurosurgery in January 1968 in a paper titled Surgical risk as related to time of intervention in the repair of intracranial aneurysms. Their question was practical rather than descriptive: surgeons of that era disagreed about whether to clip a ruptured aneurysm immediately or wait one to two weeks, and they needed a way to stratify patients so operative results could be compared fairly. They built on the earlier grading scheme proposed by E. Harry Botterell in Toronto in 1956, and added a rule that serious systemic disease such as hypertension or diabetes, or severe arterial vasospasm on angiography, moved the patient one grade worse. Hunt later revised the scheme, adding a Grade 0 for an unruptured aneurysm and a Grade Ia for a patient with a fixed deficit but no acute meningeal reaction. Dissatisfaction with the subjectivity of the original wording led the World Federation of Neurosurgical Societies to publish a competing scale in 1988 anchored to the Glasgow Coma Scale plus presence of motor deficit, while the Fisher scale of 1980 added a separate radiological axis for predicting vasospasm. Despite these alternatives the 1968 scale survived, partly because it is memorable and partly because decades of outcome literature are indexed to it; American Heart Association guidelines still reference it.