Ruptured Brain Aneurysm

What Is a Ruptured Brain Aneurysm?

When a brain aneurysm tears open, blood spills into the thin fluid-filled space surrounding the brain — the subarachnoid space. This is called an aneurysmal subarachnoid hemorrhage (aSAH). It affects roughly 6–9 people per 100,000 each year, strikes younger than most strokes (average age ~55), and carries a mortality of ~30–35% even with modern care. About 10–15% of patients die before ever reaching a hospital.

At a Glance

A ruptured brain aneurysm causes a sudden, severe headache — often described as the worst of a person's life — and is a 911 emergency
Diagnosis starts with a non-contrast CT scan of the head, sometimes followed by a spinal tap and a CT angiogram
The aneurysm should be secured within 24 hours by either endovascular coiling or open surgical clipping
Even after the aneurysm is fixed, the next two weeks are a marathon: watching for vasospasm, delayed stroke, and hydrocephalus in the ICU
Outcomes depend heavily on how severe the bleed was at arrival and how experienced the team managing it is

Symptoms

Emergency warning signs

Sudden, severe headache that reaches full intensity within a minute ('worst headache of my life' / 'like being hit in the head with a bat')
Nausea and vomiting
A stiff neck, often developing a few hours after the headache starts
Brief loss of consciousness or a seizure at the moment of rupture
Blurred or double vision, or a drooping eyelid
Weakness, numbness, or trouble speaking

The 'sentinel headache'

In roughly 10-40% of patients, a smaller warning leak occurs days to weeks before the main rupture. Any sudden severe headache that is different from a person's usual pattern deserves urgent evaluation — catching a sentinel bleed before a massive rupture can be lifesaving.

Diagnosis

Step 1: Non-contrast CT scan

When performed within 6 hours of headache onset and read by an experienced radiologist, CT is essentially 100% sensitive for subarachnoid blood.

Step 2: Lumbar puncture (if CT is negative)

Looks for red blood cells and xanthochromia (yellowish discoloration of CSF), confirming blood has been in the CSF for several hours.

Step 3: CT angiography (CTA)

Maps the blood vessels of the brain and finds the culprit aneurysm. A catheter angiogram (DSA) remains the gold standard — often performed simultaneously with endovascular coiling.

Severity grading

Hunt-Hess grade (I–V) — clinical scale based on headache, stiff neck, level of consciousness, and weakness
Fisher grade (1–4) — radiographic scale based on blood distribution on CT; predicts vasospasm risk

Types

Hunt-Hess Grades at Presentation

Grade I

Mild headache, slight neck stiffness, fully awake and oriented. Excellent candidate for early treatment; good prognosis.

Grade II

Moderate to severe headache, stiff neck, possibly a cranial nerve palsy, no weakness or confusion. Still a 'good-grade' bleed. Most patients do well with prompt treatment.

Grade III

Drowsy or confused, may have mild weakness. Intermediate grade. Outcomes still often favorable with rapid treatment and smooth ICU course.

Grade IV

Stupor, moderate to severe weakness on one side, early posturing. 'Poor-grade' bleed. High risk of hydrocephalus, vasospasm, and delayed stroke.

Grade V

Deep coma, posturing, appearing moribund. Most severe grade. Some Grade V patients recover meaningfully after emergency EVD and early aneurysm securing.

Treatment

Emergency stabilization

Admission to neurological ICU. Blood pressure carefully lowered. External ventricular drain (EVD) placed if drowsy or with large blood volume. Oral nimodipine started within 96 hours and continued for 21 days — reduces risk of delayed stroke (NEJM, 1983).

Securing the aneurysm — within 24 hours

Until the aneurysm is secured, it can re-rupture at any moment. AHA guidelines recommend treatment as early as possible and ideally within 24 hours.

Endovascular coiling

Catheter-based; soft platinum coils packed into the aneurysm sac. Lower rate of disability than surgery for many aneurysms. ISAT trial (2,143 patients) found coiling produced better chance of independence at 1 year — benefit persisted at 18 years.

Microsurgical clipping

Craniotomy; titanium clip placed across aneurysm neck. Preferred for wide-necked MCA aneurysms, aneurysms with large associated hematoma, and complex shapes not amenable to coiling. Barrow Ruptured Aneurysm Trial (BRAT) showed clipping achieved higher rates of complete obliteration and lower re-treatment rates, with comparable functional outcomes at 6 years for anterior circulation.

The next two weeks: delayed cerebral ischemia and vasospasm

Starting around day 3, peaking at days 7-10, arteries at the base of the brain can constrict (vasospasm) causing a new stroke. About 20-30% of patients develop delayed cerebral ischemia (DCI) — the single biggest driver of long-term disability in SAH. ICU management includes: daily neurological exams and transcranial Doppler, aggressive blood pressure augmentation, endovascular rescue (intra-arterial verapamil or balloon angioplasty) for severe vasospasm, and management of hydrocephalus.

Outcomes

(At High-Volume Comprehensive Stroke Centers)

Hunt-Hess Grade at Arrival	30-Day Mortality	Good Outcome at 6 mo (mRS 0-2)	What to Know
Grade I	~2-5%	~85-90%	Excellent; most return to normal life
Grade II	~5-10%	~75-85%	Good outlook with prompt treatment
Grade III	~15-20%	~55-65%	Intermediate; ICU course matters
Grade IV	~30-40%	~30-40%	Poor grade; aggressive care required
Grade V	~50-70%	~10-20%	Highest risk; recovery is possible but slow

References

Hoh BL, et al. 2023 Guideline for the Management of Patients With Aneurysmal SAH (AHA/ASA). Stroke. 2023;54(7):e314-e370. PMID: 37212182
Molyneux A, et al. ISAT — neurosurgical clipping versus endovascular coiling in 2143 patients. Lancet. 2002;360(9342):1267-1274. PMID: 12414200
Molyneux AJ, et al. Durability of coiling versus clipping: 18 year follow-up of UK ISAT cohort. Lancet. 2015;385(9969):691-697. PMID: 25465111
Spetzler RF, et al. The Barrow Ruptured Aneurysm Trial (BRAT): 6-year results. J Neurosurg. 2015;123(3):609-617. PMID: 26115467
Allen GS, et al. Nimodipine in patients with subarachnoid hemorrhage (controlled trial). NEJM. 1983;308(11):619-624. PMID: 6338383
Hunt WE, Hess RM. Surgical risk as related to time of intervention in repair of intracranial aneurysms. J Neurosurg. 1968;28(1):14-20. PMID: 5635959
Vergouwen MDI, et al. Definition of delayed cerebral ischemia after aneurysmal SAH. Stroke. 2010;41(10):2391-2395. PMID: 20798370

Our Specialists

Issam A. Awad, MD

Neurosurgery

Sean P. Polster, MD

Neurosurgery

Omer Doron, MD, PhD

Neurosurgery

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