Craniotomy and Resection of Brain Arteriovenous Malformation (AVM)
AVM resection surgery involves performing a craniotomy to directly access, carefully separate, and completely remove the AVM.
Overview
What is AVM Resection Surgery?
An arteriovenous malformation, or AVM, is an abnormal tangle of blood vessels in the brain. AVM resection surgery involves performing a craniotomy to directly access, carefully separate, and completely remove the AVM. When successful, surgical resection provides an immediate, definitive cure.
AVM surgery is a technically demanding operation. It requires meticulous microsurgical dissection to disconnect arterial feeding vessels and dissect the nidus from the surrounding brain. At One Brain and Spine, our neurosurgeons have expertise in AVM surgery and use advanced intraoperative navigation, neuromonitoring, and intraoperative angiography techniques to maximize safety.
When is Surgery Recommended for AVM?
Treatment decisions are tailored to each individual and depend on factors such as the AVM grade, location, history of bleeding, age, and symptoms. For unruptured AVMs, the balance between bleeding risk and treatment risk must be carefully weighed. Surgery is generally recommended for smaller, more accessible AVMs, and for AVMs that have already bled and caused symptoms requiring removal of the blood clot.
Ruptured vs Unruptured AVMs
A ruptured brain AVM, presenting with intracranial haemorrhage, is a medical emergency. Management of an unruptured AVM is more nuanced. The risk of treatment is weighed against the ongoing annual risk of bleeding, guided by the AVM's size, location, drainage pattern, and individual patient factors.
Treatment of a ruptured AVM prevents further bleeding, but it does not reverse the brain injury already caused by the initial haemorrhage. As a result, recovery following a ruptured AVM tends to be considerably more complex, prolonged, and unpredictable than recovery following elective treatment of an unruptured AVM. The information that follows relates specifically to surgical resection of unruptured brain AVMs.
Procedure
Preoperative Planning
Before surgery, formal cerebral angiography (DSA) is used to map out the AVM in detail, including the vessels feeding into it and draining away from it. This is combined with an MRI to understand how close the AVM is to important areas of the brain. Sometimes, preoperative embolisation may be performed by a neuro-interventionalist to reduce blood flow into the AVM.
What Happens During AVM Resection?
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. Specialised intraoperative navigation is used to accurately plan skin incision and craniotomy placement.
The AVM is approached through a craniotomy positioned over the AVM nidus. Using high-powered magnification, your surgeon carefully identifies the edges of the AVM and systematically seals and divides the blood vessels feeding into it. The tangle of vessels is then gradually separated from the healthy surrounding brain, working carefully around its edges. The vessels draining blood away from the AVM are left until last. Removing these too early, before the AVM is fully disconnected, can cause dangerous bleeding.
Once the AVM is completely separated from the surrounding brain, the draining vessels are sealed and divided, and the entire AVM is removed. Intraoperative ICG fluorescence angiography or DSA is performed to ensure the AVM has been completely removed.
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 between 2 and 6 hours depending on the complexity of the AVM.
Recovery
Recovery after AVM resection is similar to craniotomy for other conditions. Hospital stay is typically 5 to 7 days. Most patients return to normal activities within 4 to 6 weeks.
Long-Term Follow-Up
All patients who had AVM surgery require a DSA straight after surgery, and again at around 6 months, to confirm complete resection of the AVM. No long-term follow-up is typically required beyond this however your neurosurgeon will advise you based on your specific case.
Hospital Stay
After surgery, you'll initially be cared for in intensive care, usually for the first 24 to 48 hours. Most patients then stay in hospital for a total of 5 to 7 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.
Wound Care
Your incision will be closed with dissolving stitches and covered with a bandage. The compressive bandage around your head is removed after 24 to 48 hours, and the wound dressing is taken off after 72 hours. You can wash your hair with plain water after 72 hours and start using a gentle shampoo after 2 weeks. From one week after surgery, gently wiping the wound daily with an alcohol wipe will help the dissolving stitches break down properly.
Activity Guidelines
- Mobilising – you’ll be encouraged to get up and move from the day of surgery
- Heavy lifting – avoid for 6 weeks
- Driving – can usually resume after 3 months
- Desk-based work – usually possible after 4 to 6 weeks
- Physical work – usually possible after 6 to 8 weeks
- Contact sports – avoid for at least 3 months
Seizure Precautions
After brain surgery, you shouldn't drive, operate machinery, or work at heights until your neurosurgeon confirms it's safe. Rules around driving after brain surgery are set by Australian law, and this will be discussed with you at your follow-up appointment.
Warning Signs Requiring Urgent Review
- Severe headache – worse than any headache previously experienced
- New or worsening neurological deficit – weakness, speech difficulty, visual change
- Fever, wound redness, swelling, or discharge
- Seizure – present to emergency immediately
- Drowsiness or confusion
Outcomes & risks
For smaller, more accessible AVMs, complete removal is achieved in over 95%, providing an immediate cure. Clinical outcomes for these smaller AVMs are generally excellent. Larger or more complex AVMs carry a higher risk of complications.
Risks
The risks listed below are general risks that can occur with this type of surgery. If treatment is recommended for you, your neurosurgeon will go through the specific risks that apply to your individual situation.
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%
- 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
AVM-Specific Risks
- Neurological deficit – from removing an AVM near an important part of the brain. The risk depends on the size, location, and complexity of the AVM
- Haemorrhage – from inadvertent vessel injury or premature draining vein sacrifice; managed by rapid haemostasis and temporary clip application
- Normal perfusion pressure breakthrough – brain swelling or haemorrhage after AVM resection from loss of autoregulation in surrounding tissue
- Incomplete resection – residual AVM carries continued haemorrhage risk
Frequently Asked Questions — AVM Surgery Melbourne
Is surgery, radiosurgery, or observation best for my AVM?
This depends mainly on the size, location, and complexity of your AVM. Smaller, more accessible AVMs are usually best treated with surgery, offering an immediate cure. More complex AVMs may be treated with surgery, radiosurgery, or with combined embolisation and radiosurgery depending on location. The most complex AVMs are generally monitored. Your neurosurgeon will provide an individualised recommendation.
Why is the draining vein left until last during AVM surgery?
The AVM draining veins carry high-pressure blood away from the nidus. If a draining vein is sacrificed before the feeding arteries and nidus are fully disconnected, the trapped high-pressure blood has nowhere to go, which can cause dangerous bleeding. That's why surgery always follows the same careful order: first sealing off the feeding vessels, then fully separating the tangle from the surrounding brain, and only then dealing with the draining vessels.
What is intraoperative angiography and why is it used?
Special imaging is performed straight after the AVM has been removed and still under anaesthesia, to confirm that it has been completely taken out and that nothing remains. If any part of the AVM is still present, it can be addressed immediately.