Around 4-8 in 100 people with ADPKD have a small aneurysm: a ‘ballooning out’ of a blood vessel due to weakness in the vessel wall. Aneurysms may occur in the blood vessels of the brain (when they are called intracranial aneurysms, ICA or ‘berry aneurysms’).
Aneurysms affect a minority of people with ADPKD, but they are one of the most important complications because they may cause the blood vessel to burst. In the brain, this leads to a type of stroke called a subarachnoid haemorrhage. (The bleeding or haemorrhage occurs in the arteries underneath a membrane in the brain called the arachnoid, which lies just below the surface of the skull.)
Brain aneurysms rarely burst. But people with ADPKD with a brain aneurysm have a higher risk of subarachnoid haemorrhage than people without ADPKD who also have a brain aneurysm, especially if other family members have been affected. Subarachnoid haemorrhage also tends to occur at a younger age in people with ADPKD.
A subarachnoid haemorrhage can be life threatening, so screening is recommended for people with ADPKD and a family history of brain aneurysms. It is possible to treat brain aneurysms with surgery to prevent them from bursting, but this can itself be risky. So surgery is usually recommended only if its risks are less than the risks of a burst aneurysm.
The ADPKD genes PKD1 and PKD2 are now known to play a role in maintaining the structure of blood vessels. So this may explain why brain aneurysms affect several members of ADPKD families with certain genetic mutations.
However, non-inherited factors can also increase the risk of brain aneurysms in anyone:
Less than half of people with a brain aneurysm have any symptoms. Symptoms occur when the aneurysm increases in size or presses against other structures inside the brain.
Seek the immediate advice of a doctor if you or a relative has:
If a brain aneurysm bursts, the bleeding will cause sudden symptoms. Telephone for an ambulance immediately if you or a relative has:
A brain aneurysm can be diagnosed using:
Treatment depends on your own health, the size and position of the aneurysm, and the likelihood that it will burst:
A healthy lifestyle is the best way to reduce the likelihood that you will develop a brain aneurysm, or that a brain aneurysm will burst:
If you have an aneurysm, your doctor will also advise how you can reduce the risk that it will burst. But generally, you should avoid:
At present screening for brain aneurysms is not routinely recommended for everyone with ADPKD. Screening is only recommended for people with ADPKD: