Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

INITIAL

associated haematoma if significant mass effect

1st line – surgical evacuation of intracerebral haematoma

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INITIAL
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associated haematoma if significant mass effect
1st line – 

surgical evacuation of intracerebral haematoma

In patients with a ruptured arteriovenous malformation (AVM), emergent surgical evacuation of the intracerebral haematoma and control of acute bleeding may be required.[61]

Resection of deep or complex AVMs should be deferred and undertaken as a semi-elective procedure.[61] During an acute ICH episode, blood pressure lowering and reduction in blood pressure variability can reduce haematoma expansion with improved functional outcomes.[45] See Stroke due to spontaneous intracerebral haemorrhage.

Consider – external ventricular drain

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INITIAL
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associated haematoma if significant mass effect
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with hydrocephalus
Consider – 

external ventricular drain

Additional treatment recommended for SOME patients in selected patient group

Hydrocephalus secondary to intraventricular rupture of the AVM may require treatment with an external ventricular drain.

ACUTE

not surgical candidate

1st line – conservative management

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ACUTE
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not surgical candidate
1st line – 

conservative management

Very large AVMs in eloquent locations (areas of the brain that control speech, motor function, and senses) with deep venous draining veins from the intracranial circulation should be managed conservatively with symptomatic treatment of the effects of the AVM such as seizure control.

2nd line – palliative embolisation

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ACUTE
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not surgical candidate
2nd line – 

palliative embolisation

Occasionally, palliative embolisation can be offered with the aim of reducing shunt volume in the nidus to control seizures or reduce focal hypoxia ('vascular steal').

surgical candidate

1st line – surgical resection

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ACUTE
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surgical candidate
1st line – 

surgical resection

Surgical resection without embolisation may be the only treatment modality required for small, superficially placed AVMs in non-eloquent locations. Larger AVMs are more likely to require multimodality treatment.

A craniotomy is performed to expose the AVM, which is removed using standard microsurgical techniques to circumferentially excise the nidus. Feeding arterial vessels are sacrificed to the nidus itself using bipolar diathermy forceps and microscissors until the nidal draining veins are completely dearterialised. Once this has been achieved the draining vein may be taken and the nidus removed. Intraoperative neuronavigation is often used to localise the AVM nidus; alternatively, where a superficial arterialised draining vein is present on the cortical surface, this can be followed into the nidus.

Consider – staged embolisations

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ACUTE
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surgical candidate
Consider – 

staged embolisations

Additional treatment recommended for SOME patients in selected patient group

Larger AVMs usually require planned, often staged, embolisations followed by surgical excision or stereotactic radiosurgery for any residual AVM. Occasionally embolisation can be done first on deep arterial feeders, which are difficult to reach surgically but easy to reach endovascularly.

A detailed angiographic analysis of the arteries supplying the AVM, supplemented if necessary with superselective angiography, is an essential precursor to treatment planning.

Embolisations are usually performed under general anaesthesia through a femoral artery approach. N-butyl cyanoacrylate is a fast-polymerising liquid adhesive embolic agent. However, its use has been largely supplanted by the Onyx liquid embolic system, which is less adhesive and polymerises slowly, allowing for a more controlled embolisation of the nidus.[67] Other liquid embolics, such as precipitating hydrophobic injectable liquid (PHIL) and squid (a non-adhesive liquid embolic agent composed of ethylene vinyl alcohol copolymer), are also available.[68][69]

Regardless of choice, there is a risk of reflux of the embolisation agent into a feeding artery, which can result in stroke, and early obliteration or thrombosis of the draining veins can lead to periprocedural AVM rupture.[67][69]

1st line – stereotactic radiosurgery

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ACUTE
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surgical candidate
1st line – 

stereotactic radiosurgery

People with AVMs that are not surgically accessible, or in whom the overall risk of surgery outweighs that for other treatment modalities, may require treatment with stereotactic radiosurgery (SRS) with or without embolisation.

SRS using either linear accelerator-based (LINAC) radiosurgery or the 'gamma knife' enables precise delivery of a high dose of radiation to a small intracranial target while sparing the surrounding normal brain. It is usually given as a single dose. Although non-invasive, the procedure does carry risks. In particular, LINAC radiosurgery takes between 2 and 5 years to obliterate the AVM, so the patient is at risk of rebleeding during this period.[62]

Small size, non-eloquent location, low-flow pattern, and absence of perinidal angiogenesis are predictors of obliteration by radiosurgery.[14] Typically, AVMs with a diameter of less than 3 cm (volume <10 cm³) are suitable for SRS.[59]

The use of SRS specifically in Spetzler-Martin grade 1 and 2 AVMs appears to achieve obliteration in 80% of patients, with post-treatment haemorrhage occurring in 6%.[63]

Larger AVMs can be treated in several stages over 3 to 6 months;[64] staging may reduce the permanent adverse effects of radiation.[65]

AVM-associated aneurysms are strong predictors of post SRS haemorrhage. It is recommended to treat AVM associated aneurysms via microsurgery or endovascular therapy before SRS to reduce risk of haemorrhage.[61]

Consider – staged embolisations

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ACUTE
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surgical candidate
Consider – 

staged embolisations

Additional treatment recommended for SOME patients in selected patient group

AVMs associated with intranidal or extranidal aneurysms or arteriovenous fistulas may be resistant to radiosurgery, and have a higher incidence of perioperative haemorrhage.[81] When performed by experienced surgeons, embolisation prior to radiosurgery may be considered for carefully selected patients with large, complex AVM.[82]

The specific goals of pre-stereotactic radiosurgery (SRS) embolisation include making SRS feasible by reducing the nidus volume, and minimising bleeding risk in the latency period by embolising weak elements in the angioarchitecture of the nidus, such as flow-related aneurysms or high-flow fistulas.[79][80]​ The embolisation should aim to produce a compact, stable nidus.

Systematic reviews and meta-analyses report lower AVM obliteration rates in patients who have undergone embolisation followed by SRS than in those who have undergone SRS alone.[71][72][73]​ Increased treatment failure in patients who received pre-SRS embolisation may be attributable to several causes: a failure to account for differences in AVM characteristics between patients who underwent embolisation followed by SRS and those who had SRS alone (most studies are non-randomised and retrospective); patients with complex AVMs being more likely to be candidates for pre-stereotactic radiosurgery embolisation; embolisation agents causing significant imaging artifact, thereby obscuring AVM visualisation; and recanalisation after embolisation.[74][75][76][77][78]

A detailed angiographic analysis of the arteries supplying the AVM, supplemented if necessary with superselective angiography, is an essential precursor to treatment planning.

Embolisations are usually performed under general anaesthesia through a femoral artery approach. N-butyl cyanoacrylate is a fast-polymerising liquid adhesive embolic agent. However, its use has been largely supplanted by the Onyx liquid embolic system, which is less adhesive and polymerises slowly, allowing for a more controlled embolisation of the nidus.[67] Other liquid embolics, such as precipitating hydrophobic injectable liquid (PHIL) and squid (a non-adhesive liquid embolic agent composed of ethylene vinyl alcohol copolymer), are also available.[68][69]

Regardless of choice, there is a risk of reflux of the embolisation agent into a feeding artery, which can result in stroke, and early obliteration or thrombosis of the draining veins can lead to periprocedural AVM rupture.[67][69]

1st line – endovascular embolisation

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ACUTE
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surgical candidate
1st line – 

endovascular embolisation

Small AVMs with easily accessible feeding vessels may be treated by endovascular embolisation alone. However, the cure rate with embolisation alone is moderate, with an average of 20% with n-butyl cyanoacrylate (n-BCA) in older studies, and up to 50% with newer embolic agents.[59]

A detailed angiographic analysis of the arteries supplying the AVM, supplemented where necessary with superselective angiography, is an essential precursor to treatment planning.

Embolisations are usually performed under general anaesthesia through a femoral artery approach. n-BCA is a fast-polymerising liquid adhesive embolic agent. However, its use has been largely supplanted by the Onyx liquid embolic system, which is less adhesive and polymerises slowly, allowing for a more controlled embolisation of the nidus.[67] Other liquid embolics, such as precipitating hydrophobic injectable liquid (PHIL) and squid (a non-adhesive liquid embolic agent composed of ethylene vinyl alcohol copolymer), are also available.[68][69]

Regardless of choice, there is a risk of reflux of the embolisation agent into a feeding artery, which can result in stroke, and early obliteration or thrombosis of the draining veins can lead to periprocedural AVM rupture.[67][69]

pregnant

1st line – multidisciplinary care

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ACUTE
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pregnant
1st line – 

multidisciplinary care

Management of pregnancy and labour in women with AVMs requires a multidisciplinary team. Risk of intrapartum intracranial bleeding is considered low if the AVM is fully treated or intracranial bleed occurred more than 2 years ago.[90] Women at low risk of intracranial bleed can base decisions on mode of delivery based on their usual preference and obstetric indications. Risk of intrapartum intracranial bleed is high if the mother has an untreated or complex AVM or haemorrhagic episode in the past 2 years. Mothers at high risk of intracranial bleed should be offered the option of caesarean section after full discussion of the benefits and risks of each option. Women at high risk who prefer to attempt vaginal birth should be offered regional analgesia and offered the option of assisted second stage of delivery.[90]

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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