Family Brain Aneurysm FAQs

Common questions and answers about hereditary brain aneurysms. If there's a question you have not listed here, please get in touch by emailing david@hbasupport.org.

Please note that HBA Support is a not-for-profit organisation, and we are not medical professionals or qualified healthcare experts. These FAQs have been compiled based on our own experiences looking for information related to hereditary brain aneurysms. For any concerns or worries, please always speak to your GP or a clinical professional.

It's difficult to estimate exactly how many people are affected by brain aneurysms because they usually cause no symptoms and remain undetected all through life. Our recently published Targeted Literature Review showed that according to a 2005 study*, there are 7,221 cases of ruptured brain aneurysms in the UK each year. 

However, as the review highlights, the UK population has grown by 8 million people since 2005 and so there is a need for more data regarding the number of brain aneurysms in the UK. It is also impossible to tell how many of these have a hereditary pattern or are sporadic, meaning they happen suddenly and without a family history. 

*Rivero-Arias O, Gray A, Wolstenholme J. Burden of disease and costs of aneurysmal subarachnoid haemorrhage (aSAH) in the United Kingdom. Cost Eff Resour Alloc 2010;8:6. More information can be found here: Familial Intracranial Aneurysm Research and within our Targeted Literature Review

If you have a strong family history of familial intracranial aneurysms, there is 2.3% to 29.4% chance of having an unruptured brain aneurysm compared with 0.2% - 8.8% of the general population*. There are many statistics out there and you will find different numbers in different places. At the moment there is no one number that defines increased risk. More research and a better connection with the patients and their families and learning from the patient experience is needed.

Current advice from the NHS says that aneurysm screening with an imaging study of the brain vascular system (i.e. MRI scan) is recommended for people who have two or more first-degree relatives (father, mother, sister or brother) who have experienced a subarachnoid haemorrhage (where an aneurysm has burst and there is bleeding in the space between your brain and the surrounding membrane).

It is important to note that screening for brain aneurysms is a personal choice. Some people who are offered screening choose not to know due to the increased worry and anxiety it may bring. Often talking about your risks with specialists and genetic counsellors can help you understand the risks and make an informed choice for yourself.

These two guides provide useful information about screening for familial aneurysms:

Brain Aneurysms and screening from The Walton Centre

Information for adults considering screening for brain aneurysm, NHS Lothian

If an aneurysm in the brain is found, the specialist - usually a neurosurgeon or a neurovascular specialist - will work with you to determine if the aneurysm should be treated and, if so, what type of treatment to have. Sometimes the specialist may suggest a watch and wait approach, depending on the size and location of the aneurysm. That means you’ll undergo regular screening to monitor its size. If no aneurysm is detected, a repeat screening may be recommended in the future.

This is all dependent on your family history, your desire to be screened and willingness to know, and on the advice of your clinician. Not everyone wants to undergo screening and that is a personal and valid choice. It is always up to the individual to decide what’s best for them. 

For more information on brain aneurysm treatment options, please visit the NHS website: Brain aneurysm - Treatment - NHS

Are there any risk factors which increase the likelihood of a brain aneurysm?

A history of aneurysms in a family increases the risk of brain aneurysm, with unruptured brain aneurysms occurring more frequently in individuals with a strong family history of brain aneurysms. Environmental factors, such as smoking and high alcohol consumption can also increase the likelihood of a brain aneurysm. 

For more information, please see the NHS website: Brain aneurysm - Prevention - NHS

What’s the latest NHS advice if I think that I may be at risk from a hereditary brain aneurysm? There is limited information and guidance on the NHS website about familial disease.  Please follow the link for the information including details about how brain aneurysms are diagnosed and treated.

According to the National Institute for Health and Care Excellence (NICE), an executive non-departmental public body of the Department of Health and Social Care in England, screening is recommended for people thought to have a significant risk of having a brain aneurysm that could rupture at some point in the future. This relates to those who have two or more first-degree relatives (father, mother, sister or brother) who experienced a subarachnoid haemorrhage. Of course, not everyone wants to undergo screening and that is a personal choice. It is always up to the individual to decide. 

If you have a strong family history, including two or more first-degree relatives, members of your close family (parents, brothers, and sisters) may also be advised to have an MRA - Magnetic Resonance Angiography or MRI - Magnetic Resonance Imaging scan to check for possible aneurysms too.

If you have any questions or concerns, talk to your GP about your family history and your worries. They can then advise on the next steps and how to access NHS screening. You may also be referred to a genetic counsellor to talk through your family history and decide whether screening is right for you.

More information can be found on Genetic and genomic testing on NHS

NHS Lothian has produced a useful guide for people who are considering screening for brain aneurysms. See: Information for adults considering screening for brain aneurysm

If you have been diagnosed with a hereditary brain aneurysm we offer useful information to help you. Although everyone's journey will be different, there are a number of options open to you. You can discuss the best options for you with your specialist or neurosurgeon.

For more information on treatment options, please visit the NHS website: Brain aneurysm - Treatment - NHS

Who can I talk to if I've been diagnosed with a brain aneurysm? If you are worried and would like to talk through your concerns with a trained specialist, the Brain & Spine Foundation Helpline nurses can help you by talking through your questions and providing explanations on anything you don’t fully understand. They are there to help and can be contacted on 0808 808 1000

The Brain & Spine Foundation is a great place to get support and information, helping you to tackle concerns and help inform your choices and plans. The information and support available includes:

If you are worried about brain aneurysm subarachnoid haemorrhage, you could contact your GP who can talk you through options and may refer you to a genetic counsellor (a specialist in hereditary conditions such as HBA).

For more immediate support, you can talk to a trained specialist at the Brain & Spine Foundation. Their Helpline nurses can help you by talking through your questions and providing explanations on anything you don’t fully understand. They are there to help and can be contacted on 0808 808 1000

Within the ‘Targeted Literature Review’ (a look at the research available on this condition) published by HBA Support in 2022 a review and summary of current genetic research shows there are multiple genetic candidates that cause hereditary brain aneurysms. However, there is currently no consensus and insufficient understanding of these in the clinical community. More research is needed to help build the list of genetic candidates and understand their significance. It is hoped that, eventually, genetic screening (a simple blood test) would allow early diagnosis of those at risk of brain aneurysm subarachnoid haemorrhage so that preventative measures can be taken.

In February 2021, NICE also concluded, through its review of treatment, that more research is needed in this important area. The NICE report on Subarachnoid haemorrhage caused by a ruptured aneurysm: diagnosis and management explored routes to diagnosing and treating an aneurysmal (caused by a ruptured aneurysm) subarachnoid haemorrhage and its complications, and provides recommendations to improve the speed and accuracy of diagnosis and ensure that the most effective treatments are offered.

Our Targeted Literature Review highlights some of the many studies that investigate the genetic causes of hereditary brain aneurysms. Our report highlights the most common variants that have bene identified in global research. More needs to be done to improve our understanding of the genetic causes. We hope that by working with the research community we can increase our knowledge into what the genetic factors may be and improve the diagnosis and treatment journey for families.

Just like heart attacks, ruptures or aneurysm haemorrhages (where an aneurysm bursts) are usually one-off events in someone's life and usually don’t carry a hereditary risk. Sometimes though, patterns occur in families. When this happens, further investigation is needed.

Current NHS guidance on brain aneurysms states that brain aneurysms can develop in anyone at any age but are more common in people over the age of 40 and women tend to be affected more commonly than men. 

Most aneurysms happen without any family history. This is often down to bad luck although sometimes environmental factors, such as smoking, high blood pressure and excess alcohol can play a part.

A history of intracranial aneurysms in a family also increases the risk, with the prevalence of unruptured brain aneurysms higher in individuals with a strong family history of brain aneurysm. View the Targeted Literature Review for more information. If aneurysms are proven to run in families, the condition is known as familial intracranial aneurysms (FIA) or familial aneurysms syndrome (FAS).

I'm feeling worried, who can help?

The Brain & Spine Foundation is a great place to get support and information, helping you to tackle concerns and help inform your choices and plans. The information and support available includes:



If you are worried, you could contact your GP who can talk you through options and may refer you to a genetic counsellor (a specialist in hereditary conditions).


For more immediate support, you can talk to a trained specialist at the Brain & Spine Foundation. Their Helpline nurses can help you by talking through your questions and providing explanations on anything you don’t fully understand. They are there to help and can be contacted on 0808 808 1000.

Speak to Brain & Spine Foundation

Latest guidelines from NICE for familial brain aneurysms

The latest advice from NICE covers diagnosing and treating an aneurysmal (caused by a ruptured aneurysm) subarachnoid haemorrhage (where an aneurysm has burst and there is bleeding in the space between your brain and the surrounding membrane) and its complications. It provides recommendations to improve the speed and accuracy of diagnosis and ensure that the most effective treatments are offered, together with guidance on follow-up care and information for people (aged 16 and over) who have had an aneurysmal subarachnoid haemorrhage, their families and carers.

Within this latest draft guide, the authors also recommended that additional research was needed to look into familial risk and advice for families.

Extract taken from draft-guideline (nice.org.uk)

“The committee recognised that first-degree relatives of people who have had an aneurysmal subarachnoid haemorrhage are at higher risk of intracranial arterial aneurysm than the general population. The committee agreed that investigating for aneurysms in first-degree relatives may produce health benefits but could also lead to harm, including unnecessary anxiety and a consequent increase in visits to GPs and emergency departments. Moreover, the optimal timing and frequency of investigations to detect and monitor intracranial aneurysms in first-degree relatives is unknown. The committee were aware that the NHS does not currently support routine screening for intracranial arterial aneurysms in relatives and any change in NHS policy could have a significant resource impact.

The committee acknowledged that in current practice investigation is typically only recommended for people thought to have a significant risk of having a brain aneurysm that could rupture at some point in the future, and this would usually only apply to people with 2 or more first-degree relatives who have had an aneurysmal subarachnoid haemorrhage. This reflects the advice given on the NHS website on screening for brain aneurysms.

The committee agreed that the lack of evidence for routine testing of relatives and current practice on testing should be explained to people who have had a subarachnoid haemorrhage, and their families as appropriate. Given the importance of this issue and the lack of evidence, the committee made a recommendation for research on investigations for relatives”.

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