Revision 27 for 'Ruptured berry aneurysm'

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Ruptured berry aneurysm

Rupture of a berry aneurysm, also known as a saccular aneurysm, can cause either a subarachnoid hemorrhage (SAH), cerebral hematoma and/or intraventricular hemorrhage.


Berry aneurysms form 97% of aneurysms of the central nervous system. Up to 80% of patients with a spontaneous subarachnoid hemorrhage have ruptured an aneurysm. 90% of these aneurysms are located in the anterior circulation (carotid system) and 10% are found in the posterior circulation (vertebrobasilar system).

Clinical presentation

Rupture of a saccular aneurysm with associated subarachnoid hemorrhage most frequently presents with a sudden, excruciating headache often described as 'the worst I've ever had' or 'thunderclap' resulting from blood being forced into the subarachnoid space under arterial pressure. Other features include:

  • visual changes
  • facial pain
  • seizures
  • autonomic disturbances (nausea/vomiting, chills and palpitations)
  • focal neurology (sensory loss, weakness, memory loss, language difficulties) 

Examination findings include nuchal ridigity, altered consciousness, and focal neurological signs such as ophthalmoplegia and pupillary abnormalities

Mortality from first rupture is between 25-50% with repeat bleeding a common complication in survivors. With each recurrent bleed, prognosis is worsened. In the first few days following a subarachnoid hemorrhage, there is an increased risk of additional ischemic injury from the reactive vasospasm from surrounding vasculature. 5


The pathology of the formation of a berry aneurysm is large unknown but rupture usually manifests as a devastating subarachnoid hemorrhage. 5

  • formation of berry aneurysm:
  • rupture of berry aneurysm
    • two thirds are sporadic
    • one third of cases associated with increased intracranial pressure 6
  • most commonly at arterial branching points along the circle of Willis 5
Macroscopic appearance
  • an unruptured aneurysm appears as a thin-walled, shiny red outpouching usually measuring a few milimeters to 3 cm in diameter 
  • rupture usually occurs at the apex of the sac 5
Microscopic appearance
  • the arterial wall adjacent to the neck of the sac usually shows thickening of the intima and thinning out of the media as the neck is approached
  • the sac itself is usually made up of thickened intima with the adventitia of the parent artery surrounding the sac 5

Radiographic features

Determining the site of rupture

After rupture, the location of the blood or hematoma can help determine the site of the ruptured aneurysm in the majority of cases:

Aneurysmal characteristics suggestive of rupture 4
  • length-to-neck ratio > 1.6
  • increased volume to surface area
  • aneurysm angulation
  • presence of an apical bleb

Treatment and prognosis

The rupture of an intracranial aneurysm is a medical emergency with a high mortality index 3.  

See also

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