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There is currently a great deal of confusing advice available about whether patients should be screened for cerebral aneurysms that have not caused symptoms. This reflects a good deal of uncertainty in the medical profession as to whether such screening actualy protects patients from harm. There remains general concern that seeking out asymptomatic aneurysms may unnecessarily expose patients to risks from treatment or to anxiety about a condition which would not be otherwise affecting them.

If you are considering screening we recommend speaking to a specialist with experience of treating cerebral aneurysms before undergoing any imaging tests.



Given the well documented risks of death or disability resulting from aneurysm rupture it is superficially attractive to secure them before they can cause harm. However the following need to be borne in mind:

  • Not every aneurysm will go on to rupture
  • The treatment of an unruptured aneurysm carries risks to life and independence of its own
  • The risk of treating aneurysm may so outweigh the short term benfit that conservative treatment is recommended
  • A negative MR or CT scan today is not a guarantee that an aneurysm could not develop in the future.

There is little good quality scientific data to guide us as to which patients might benefit from screening. In the future we hope that a better understanding of an

  • individual's genetic make-up
  • enviromental risk factors (e.g. smoking) individuals are exposed to
  • specialised tests to determine potential weaknesses in the blood vessel wall

will allow us to offer a better estimate of the individual's future risk. It remains the case that no-one is able to predict the future with certainty.



What is the evidence that screening is effective?

DecisionA great deal of effort has gone into understanding the natural history of a cerebral aneurysm- that is; what occurs if the aneurysm is left without treatment. You may find the information in our section on unruptured aneurysms of interest as well. At present the highest quality evidence comes from the two International Studies on Unruptured Intracranial Aneurysms (ISUIA 1 and 2) and the UCAS study from Japan.

The smallest aneurysms appear to have relatively small risks of bleeding in the short term. The results of ISUIA2 are frequently, but wrongly, cited as indicating small anterior circulation aneurysms below 7mm in diameter have no risk of bleeding in the short term. It is more correct to say the results indicate that these aneurysms risk of bleeding may be less than the risks of treatment in the short term. We also see that the risk of treatment increases as the aneurysms grow larger. A careful balance must therefore be struck between the risk of intervening and what could be gained from treating the aneurysm.

As one gets older the number of life-years one might gain by treating an unruptured aneurysm reduces. Inevitably the risks assosciated wiith treatment tend to rise later in life and the risk to benefit. Furhtermore the above is likely to be rather an oversimplification of what promotes aneurysmal bleeding. The shape and size of the affected blood vessels may have a hydrodynamic affect which increases the stresses on the wall of the aneurysm

For some the discovery of an unruptured aneurysm, even if believed to be of relatively low-risk, may become a psychological burden. The management of each aneurysm must therefore be considered on a case-by-case basis. There is usually not pressure to reach a final decision quickly and it is important to take time to arrive at the right decision for the individual.


Should children be screened?

Cerebral aneurysm rupture before the age of 18 years is rare. Paediatric aneurysms account for approximately between 0.005 and 2% of all aneurysms seen.

They may be assosciated with underlying genetic conditions which are themselves very rare.

Becuase of their rareity we currently do not recommend that children be screened for aneurysms. If parents have concerns it may be useful to discuss with a neurovascular specialist and or genetic counsellor.

Other Conditions Assosciated with Cerebral Aneurysms.

Diseases may predispose to the development of brain aneurysm :

Directly e.g. genes malfunction resulting in fragility of blood vessels

or

Indirectly e.g. Adult polycystic kidney disease may result in kidney faiure which itself causes high blood pressure and which in turn is associated with the developemnt and rupture of brain aneurysms.

If affected by such a condition screening for cerebral aneurysms still poses the questions described above. In fact there is often less scientific data on what happens should the aneurysm be left untreated (the natural history)

Treatment of aneurysm may be indicated if it can be shown to benefit the patient in the longer term. It is worthwhile to discuss the condition with an experienced specialist before carrying out imaging. The research data we have on risk from unruptured aneurysm may not apply to aneurysms assosciated with other conditions and they may have a higher lifetime risk of bleeding.