What is the risk of mortality and morbidity with a brain aneurysm bleed?

Mortality and Morbidity Associated with Brain Aneurysm Bleeding

Brain aneurysm bleeding carries a high mortality rate of approximately 45% at 30 days, with the majority of deaths occurring in the first days after subarachnoid hemorrhage (SAH). 1

Mortality Risk Factors

Initial Hemorrhage Severity

• The severity of the initial bleed is the most important determinant of outcome after aneurysmal SAH 1, 2
• Case fatality rate for aneurysmal SAH remains high despite advances in treatment 1
• In-hospital death rates among SAH patients admitted through emergency departments are approximately 33% 1

Rebleeding Risk

• Rebleeding carries an extremely high mortality rate of 70% 1
• Rebleeding risk is highest in the first 24 hours (15% "ultraearly rebleeding") 1
  • 70% of ultraearly rebleeds occur within 2 hours of initial SAH
  • All preoperative rebleeding occurred within 12 hours of initial SAH in one study
• After the first day, rebleeding risk is approximately 1-2% per day for the first month 1
• Overall rebleeding risk is 20-30% in the first month without treatment 1

Timing Pattern of Rebleeds

• 35% of rebleeds occur in the first 24 hours
• 5% between days 1-3
• 19% between days 4-7
• 41% after the first week 3

Morbidity Risk Factors

Treatment-Related Morbidity

• Surgical clipping: Combined morbidity and mortality at 1 year is 10.1% for patients without prior SAH and 12.6% for patients with prior SAH 1
• Endovascular coiling: Combined morbidity and mortality at 1 year is 7.1% for patients without prior SAH and 9.8% for patients with prior SAH 1
• For unruptured aneurysms <10mm, surgical morbidity is approximately 0.6% and mortality is near 0% 4
• For unruptured aneurysms >10mm, surgical morbidity increases to 6.1% and mortality to 1.2% 4

Patient Factors Affecting Outcomes

• Age: Patients >50 years have higher surgical risk but not higher rupture risk 1
• Young patients (<50 years) with asymptomatic aneurysms have the lowest surgical morbidity (5-6% at 1 year) 1
• Patients >70 years experience more temporary deficits after surgery 4

Aneurysm Characteristics

• Size: Larger aneurysms (>7mm) have higher rupture risk 1
• Location: Posterior circulation aneurysms have higher rupture risk (2.5-50% depending on size) compared to anterior circulation (0-40%) 1
• Aneurysms in anterior cerebral artery or middle cerebral artery locations have lower surgical morbidity (0.3%) 4

Long-Term Outcomes

Neurological Deficits

• Patients with no gross neurological deficits after SAH frequently have subtle cognitive or neurobehavioral difficulties 1
• These deficits impair social adjustment and ability to return to previous occupations 1
• Cognitive deficits may not correlate with visible tissue loss on MRI 1

Functional Outcomes by Treatment

• In patients with poor neurological status post-SAH (Hunt and Hess Grades IV-V):
  • Good recovery: 25.3% with nimodipine treatment vs. 10.9% with placebo 5
  • Severe disability: 6.9% with nimodipine vs. 14.9% with placebo 5
  • Vegetative survival: 4.6% with nimodipine vs. 8.9% with placebo 5
  • Death: 54.0% with nimodipine vs. 53.5% with placebo 5

Clinical Presentation and Diagnosis

Common Symptoms

• Severe headache (74-80% of patients) - often described as "the worst headache of my life" 2
• Nausea and vomiting (77% of patients) 2
• Loss of consciousness (53% of patients) 2
• Nuchal rigidity/stiff neck (35% of patients) 2
• Photophobia (common) 2
• Seizures (up to 20% of patients, most commonly in first 24 hours) 2

Diagnostic Pitfalls

• Misdiagnosis occurs in approximately 12% of cases 2
• Misdiagnosis is associated with a nearly 4-fold higher likelihood of death or disability at 1 year 2
• "Sentinel headaches" occur in 10-43% of patients, typically 2-8 weeks before major rupture 2

Management Considerations

Immediate Treatment

• Nimodipine is indicated for all patients with SAH to improve neurological outcomes 5
• Blood pressure control is essential (target systolic <160 mmHg) to balance rebleeding risk and cerebral perfusion 2
• Early transfer to high-volume centers (>35 SAH cases/year) improves outcomes 2

Complications to Monitor

• Vasospasm occurs in 30-70% of patients with aneurysmal SAH 2
• Approximately 15-20% of patients suffer stroke or die from vasospasm despite maximal therapy 2
• Acute hydrocephalus requires prompt CSF diversion 2

Prevention of Poor Outcomes

• Early admission and treatment within the first 72 hours post-bleed could potentially prevent up to 65% of late rebleeds 3
• Approximately 35% of rebleeds could be avoided with timely admission and recognition of initial symptoms 3

In conclusion, brain aneurysm bleeding represents a serious medical emergency with high mortality and morbidity rates. The outcome is primarily determined by the severity of the initial hemorrhage, with rebleeding carrying a particularly poor prognosis. Early recognition, prompt transfer to specialized centers, and appropriate treatment can significantly improve outcomes.