Craniotomy and Clipping of Cerebral Aneurysm

What is Aneurysm Clipping?

Aneurysm clipping is an operation where a small titanium clip is placed across the base of a brain aneurysm – a weak, bulging area in a blood vessel wall – to permanently seal it off from normal blood flow. This stops the aneurysm from growing or bleeding, while keeping blood flowing normally through the healthy parts of the artery. It is a technically demanding operation and is performed using high-power operative microscopy with intraoperative angiography.

Aneurysm clipping provides a definitive, long-term treatment for brain aneurysms. It has an occlusion rate exceeding 98% at 10 years. Clipping is generally the preferred option for aneurysms in certain locations, aneurysms with complex neck anatomy and large or giant aneurysms. One Brain and Spine's neurosurgeons perform aneurysm treatment in close collaboration with neuro-interventionalists, offering patients both surgical and endovascular modalities.

Ruptured vs Unruptured Aneurysm

A ruptured brain aneurysm, presenting with subarachnoid haemorrhage (SAH), is a medical emergency requiring urgent treatment to prevent further bleeding. Unruptured aneurysm management is more nuanced. The risk of treatment is weighed against the annual rupture risk, guided by aneurysm size, shape, location, and patient factors.

Treatment of a ruptured brain aneurysm prevents further bleeding, but it does not reverse the brain injury already caused by the initial haemorrhage. As a result, recovery following a ruptured aneurysm tends to be considerably more complex, prolonged, and unpredictable than recovery following elective treatment of an unruptured aneurysm. The information that follows relates specifically to the clipping of unruptured brain aneurysms.

Preoperative Planning

Before surgery, detailed scans of the blood vessels are essential to understand the exact shape of the aneurysm and how it connects to the surrounding arteries. A specialised scan called cerebral angiography (DSA) gives the most detailed picture of the aneurysm's shape and its relationship to nearby blood vessels. In some cases, a CT scan of the blood vessels (CT angiography) provides enough detail on its own, meaning the more detailed DSA scan isn't always necessary.

What Happens During Aneurysm Clipping?

The procedure is performed under general anaesthesia with careful blood pressure and cardiovascular management throughout. Your head is carefully positioned and held still during surgery. An incision is usually planned on the affected side, just behind your hairline. A small opening is then made in the skull, most commonly over the side of the head near the temple. The tough membrane covering the brain, called the dura, is opened.

Working carefully underneath the brain, using high-powered magnification, your neurosurgeon gently makes their way to the aneurysm, identifies the artery it's arising from and the surrounding blood vessels, and places one or more small titanium clips precisely across its base. A special dye called indocyanine green (ICG) fluorescence, is then used to light up the blood vessels and confirm the aneurysm is fully occluded and that all the normal blood vessels are patent.

The dura is closed and the piece of skull is put back in place and secured with small plates, screws, and bone cement. The muscle and skin are then closed in layers, with dissolving stitches used for the final layer.

The operation usually takes 2 to 3 hours.

Unruptured Aneurysm

Recovery from elective clipping of an unruptured aneurysm is similar to craniotomy for other conditions. Hospital stay is typically 3 to 5 days. Most patients return to normal activities within 4 to 6 weeks.

Long-Term Follow-Up

All patients who've had a clipped aneurysm will have a follow-up CT scan of the blood vessels straight after surgery, and again at 12 months, to confirm continued aneurysm exclusion. After this, further scans are usually done every 3 to 5 years to check for any new aneurysms developing over time.

Hospital Stay

After surgery, you'll initially be cared for in intensive care, usually for the first 24 hours. Most patients then stay in hospital for a total of 3 to 5 days, depending on the type of surgery and how your recovery is progressing. Some patients – particularly those who've had a more complex procedure, or who had symptoms before surgery – may need a longer hospital stay or a period of rehabilitation.

In experienced hands, complete aneurysm occlusion is achieved in over 98% of cases. For unruptured aneurysms, the large majority of patients return to normal neurological function after surgery.

Anaesthetic Risks

As with any general anaesthetic, there's a small risk of cardiac, pulmonary, and thromboembolic complications. This risk is reduced through careful assessment before your operation.

General Craniotomy Risks

• Wound infection – approximately 1 – 2%
• Intracranial bleeding – postoperative haematoma requiring return to theatre; less than 1%
• CSF leak – from wound; usually managed conservatively
• Seizures – new seizures following craniotomy. This may require long-term anti-epileptic medication and a more prolonged period of driving restrictions
• Neurological deficit – new weakness, speech difficulty, visual change, or cognitive change
• Death – a very rare but acknowledged risk of any cranial procedure

Aneurysm-Specific Risks

• Intraoperative aneurysm rupture – bleeding during dissection. It occurs in around 5–10% of cases, and typically doesn't affect the overall outcome of the surgery
• Stroke – from inadvertent occlusion of a branch vessel. The risk is minimized by using various techniques during surgery