Brain aneurysms and subarachnoid haemorrhage

An aneurysm is an expansion or ballooning of a blood vessel wall within the brain. It usually develops slowly over many years and doesn't cause any problem until it bleeds without warning. The bleeding is called subarachnoid haemorrhage (SAH) because the blood fills the space under the arachnoid layer, which is the thin clear membrane around the brain. The bleeding can be very small or very large and devastating. If the bleed is a small one, patients usually experience a sudden severe headache. They may complain of neck stiffness, or sensitivity to bright light. If the bleed is a very large one, this can even result in sudden unconsciousness, coma or death.

The major risk in the first few days after a SAH is that the aneurysm may rupure and bleed further. Therefore the main aim of neurosurgery treatment early on is to identify the location of the aneurysm and block it off. The aneurysm can be identified on scans such as a CT scan (with contrast) or a cerebral angiogram. In this test, a needle is placed into the femoral artery in the groin, contrast dye injected and Xrays taken of the brain from various angles. This highlights the blood vessels and the aneurysm.

Sometimes, aneurysms are found before they have ruptured and bled because of a scan done for some other reason. In this case there is less urgency to treat the aneurysm and it can often be planned as an elective procedure. Your neurosurgeon will discuss with you the various factors regarding the decision whether to treat the aneurysm, how it could be done and the timing.

Once the aneurysm is identified, it can be treated in two ways:

1. Craniotomy and clipping
In this operation, a part of the skull is removed to gain access to the aneurysm, and then a small clip is placed across the neck of the aneurysm to completely block it off from the circulation so it can't bleed again.

2. Endovascular coiling
This procedure is similar to the cerebral angiogram and is performed by a specialist radiologist, trained in neurovascular treatment. A thin catheter is threaded up to the aneurysm through the blood vessels and then the aneurysm is filled with 'coils' - thin, soft metal wires that coil around inside the aneurysm walls, causing a blood clot to form and block the blood flow into it.

Both methods of treating the aneurysm require a general anaesthetic.

If the aneurysm has been treated electively (before any haemorrhage has occurred), the patient can usually expect to be home after 5-6 days. However, in the case of a ruptured aneurysm, the recovery is much prolonged and depends on the recovery from the haemorrhage. The blood around the brain does eventually wash away, but usually the patient is kept in hospital for around 2 weeks to make sure that no other complications occur such as a stroke, vasospasm or hydrocephalus.