What is an aneurysm?
An aneurysm is a weakness of the blood vessel. In the brain it looks like a grape and is seen most commonly where normal blood vessels divide.
The main cause for concern with an aneurysm is that it can give way suddenly and cause a brain haemorrhage.
Healthy normal people can have an aneurysm and not know about it. Indeed in many people an aneurysm never causes problems. Predicting which aneurysms cause problems and which don't is difficult and this is best discussed with an expert.
It is important to know however that not all aneurysms will rupture. It is estimated that between 2-4 out of every 100 people have an aneurysm of which only 1/3 will ever be troubled by a brain haemorrhage. This means that about 66% of people with an aneurysm that has not ruptured will not have any problems with their aneurysm.
What does a brain aneurysm look like?
Brain aneurysms come in various shapes and sizes. Most commonly they take the form of a grape and 90% of brain aneurysms are called saccular or ‘berry’ aneurysms. Rarely aneurysms can occur as a result of disease and bulging of the entire blood vessel and these are called fusiform aneurysms. Equally rarely an aneurysm can form as a result of a tear in the lining of the blood vessel and this is called a dissecting aneurysm.
What causes a brain aneurysm?
The reason why people develop brain aneurysms is not clear. Women are more affected then men. Patients that have problems with high blood pressure and those that smoke are also more likely to develop aneurysms. Patients with a family history of aneurysm may be more at risk, as are patients with polycystic kidney disease and those with connective tissue disorders such as Ehlers–Danlos syndrome.
What are the symptoms of a brain aneurysm?
Most aneurysms do not cause any problems. Predicting which aneurysm is going to cause a problem is difficult and requires balancing a number of factors which can only be done by an expert. In general however larger aneurysms are more likely to cause problems compared to smaller aneurysms.
Most aneurysms are found because a scan was done to look for other reasons. When an aneurysm causes problems it does so most commonly because it has ruptured.
An aneurysm rupture classically presents with a sudden, severe headache, “the worst headache”.
It can be accompanied by:
- neck stiffness
- blurred or double vision
- sensitivity to light
- drooping eyelid
- trouble speaking or a change in awareness and mental state
- trouble walking or dizziness
- nausea or vomiting
- seizure (convulsion)
- loss of consciousnes
This needs emergency medical treatment and should be managed in hospital
Whilst most unruptured aneurysms do not cause problems they can present with:
- headache or pain behind or above the eye, which can be mild or severe
- blurred or double vision
- visual deficits
How is a brain aneurysm diagnosed?
Most aneurysms get diagnosed on a brain scan (MRI or CT scan) that a doctor has organised because of problems (usually unrelated) that you may be experiencing. Rarely does an aneurysm cause specific symptoms that mean an investigation needs to be done for it.
Once an aneurysm is diagnosed then additional tests such as an MR or CT angiogram (non-invasive tests designed specifically to study the blood vessels of the brain) may be performed. If treatment of an aneurysm is being proposed, most patients will need a formal dye test of the blood vessels of the brain (digital subtraction angiogram) which is an invasive procedure requiring a short stay in hospital.
Treating brain aneurysms
Treatment for an aneurysm is made on an individual basis. Decisions are taken in conjunction with the patient and after discussion at a multidisciplinary team meeting (MDT) of specialists that treat aneurysms.
Life style changes are an important part of treatment and include refraining from smoking, eating and maintaining a healthy diet, exercising regularly and ensuring good weight control, managing high blood pressure and making sure that blood pressure medication is taken regularly if prescribed.
In some cases as specialists we will recommend treatment of the aneurysm.
This can be done by :
- open microneurosurgery and closing of the weakness by applying a titanium clip across the neck of the aneurysm.
- endovascular coiling, in which the aneurysm is packed off with small platinum coils which are placed under X-ray guidance using small catheters which are passed from the groin to the blood vessel abnormality