Updated 21 May 2015

Cerebral aneurysm

Cerebral aneurysm is a common congenital cerebro-vascular disorder.



  • Cerebral aneurysm is a common congenital cerebro-vascular disorder caused by a weakness in the wall of a cerebral artery or vein.
  • Cerebral aneurysms occur more commonly in adults than in children.
  • The majority of patients with aneurysms experience no warning before their attacks. Occasionally aneurysms bursting may be preceded by so-called "sentinel bleeds": small bleeds giving rise to many of the symptoms associated with aneurysms and resolving spontaneously.


The disorder arises from congenital defects in the blood vessel. Cerebral aneurysms occur more commonly in adults than in children and are slightly more common in women than in men, however they may occur at any age.


Before an aneurysm ruptures, the individual may experience a variety of symptoms depending on the location of the aneurysm, or the individual may be asymptomatic, experiencing no symptoms at all. Onset is usually sudden and without warning. A sudden headache and vomiting on alteration of consciousness may indicate rupture.

Rupture of a cerebral aneurysm is dangerous and usually results in bleeding in the brain or in the area surrounding the brain, leading to sub-arachnoid space bleeding, which results in intense neck stiffness, headache, double vision, nausea and vomiting. Intra-cranial haematoma (a mass of blood, which may be clotted and is within the skull) may occur.

Re-bleedings, hydrocephalus (blockage of the ventricular system within the brain as a result of clotted blood), vasospasm (spasm of the blood vessels) or multiple aneurysms may also occur.


The prognosis for a patient with a ruptured cerebral aneurysm depends on the extent and location of the aneurysm, the person’s age, general health, and neurological condition. 50% of individuals with a ruptured cerebral aneurysm die from the initial bleeding. Other individuals with cerebral aneurysm recover with little or no neurological deficit. Early diagnosis and treatment of the ruptured vessel are vital. Patients who develop coma after aneurysmal bleed usually have a very poor prognosis, and major surgery with clipping of the aneurysm is unlikely to improve this.


Emergency treatment for individuals with a ruptured cerebral aneurysm generally includes restoring deteriorating respiration and reducing intra-cranial pressure.

Surgery is usually performed as soon as possible to clip the ruptured aneurysm and to reduce the risk of re-bleeding.

In patients for whom surgery is considered too risky, microcoil thrombosis or balloon embolisation may be performed.

The major problems associated with patients who survive immediately after an aneurysmal bleed are vasospasm(generalized constriction of bood vessels due to irritation from the blood products) and rebleeding. Rebleeding is best treated by operating as soon as possible. Vasospasm is best treated by increasing fluid and raising blood pressure, both of which are only possible once the aneurysm has been clipped.

Other treatments may include bed rest, medication therapy, or hypertensive-hypervolemic therapy (hypervolemic haemodilution) to control vasospasm.

Reviewed by Dr J. Carr


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