Arteriovenous malformation

Dr Hieu

Nguyen Ngoc Anh, F, 9 years old, A13 Clinical diagnosis: seizure.

Clinical findings

Pre-history: cerebral hemorrhage. No fever, no headache, no vomitting. No paralysis seizure: 1 months before being

hospitalized.

DSA >>>> AVM Treated by embolization.

Definition

Vascular abnormality constituted by a complex, tangled wed of afferent arteries and draining veins linked by an abnormal dysplastic intervening capillary bed

Contrast with a AVF which has direct fistulous connection without intervening nidus

Etiology Initially thought to be congenital May be due to aberrant vasculogenesis and

angiongenesis in embryonic Failure of the embryonic vascular plexus to

fully differentiate and develop a mature capillary bed in affected area.

It is likely that a combination of congenital predisposition and extrinsic factors lead to their generation

Epidemiology In the US general population is 1.4/100,000

per year No sexual preference Mean age of presentation: 20 – 40 Account for 3% stroke and 33% primary

intracranial bleeding in young adults. 1/10 have aneurysms.

Angioarchitecture

Arterial feeder Nidus Draining vein Intervening gliotic parenchyma

Angioarchitecture

Arterial feeder

Single or multiple Pial, perforating or dural Direct feeders supply as terminal

branch Indirect feeder supply.

Nidus

The AVM nidus is a compact plexiform of dysplastic, thin-walled vessels connecting feeding arteries to draining veins.

An AVM nidus can either be globular or conical in shape; may be compact or diffuse.

Within the nidus, arterial blood is shunted directly into draining veins without passage through a normal high – resistance arterial capillary network.

AVM syndromes Sturge – Weber syndrome. Rendu-Osler-Weber syndrome:

autosomal-dominant syndrome of multiple visceral, mucosal and cerebral vascular malformation.

Wyburn-Manson syndrome: unilateral retinal angiomatosis and cutaneous hemangioma in an ipsilateral trigerminal distribution, AVM located in midbrain.

Distribution

Based on autopsy findings: Cerebral hemisphere: 60 – 70% Cerebellum: 11 – 18 % Brainstem: 13 – 16 % Deep seated: 8 – 9 %

Clinical symptoms

Hemorrhage (54%) Seizures (46%) Headache (35%) Neurological deficits Asymptomatic Pediatric: hydrocephalus, heart failure

Factors increasing the Risk of Bleeding

Most common symptom Nidus:

82% in small AVM 29% in medium – sized AVM 12% in large AVM

Location: deep locations Basal ganglia Periventricular Intraventricular

Factors increasing the Risk of Bleeding

Deep venous drainage Venous stenosis Single draining vein Feeding artery pressures Hemorrhage before

Types and size of AVM

Micro AVM: < 1cm Small AVM: 1 – 3 cm Moderate AVM: 3 – 6 cm Large AVM: > 6 cm

CT Scan imaging

CT is usually the first imaging modality used to rule out hemorrhage

Parenchyma calcifications are observed in 20% of cases.

Multi - slice CT Scan angiography

AVM diagnosis

Clinical symptoms CT scanner MRI DSA

CT Scan

CT is usually the first imaging modality used to rule out hemorrhage

Calcification: 20% CT angiography: dynamic contrast

CT Scan

MRI

On T1 and T2W images: plexiform flow void phenomenon.

T1W with gadolinium: vessels are enhanced.

Measure the size and the anatomic location of the nidus.

MR angiography: with and without contrast

MRI

MRI

DSA

Gold standard to evaluate AVM Selective angiongraphy is always

necessary to make a decision to plan the treatment

Different diagnosis

Venous malformation Cavernoma AVF Telangectasia

Classification ( Spetzler Martin) Size of nidus

– Small (<3cm): 1– Medium (3-6cm): 2– Large (>6cm): 3

Eloquence area– Yes: 1– No: 0

Deep venous drainage– Yes: 1– No: 0

Spetzler Martin grading

Grading AVMs according to their degree of surgical difficulty and risk of surgical morbidity and mortality

There are 5 grades Low grade AVM: Grade I, II, Medium grade: Grade III High grade AVM: Grade IV, V

Management

Observation: large AVM, no bleeding before

Surgery Embolization Radiosurgery Combination treatment

Surgery

The most effective treatment: small and superfacial AVM.

Pediatric: > 5 years old. Remove large, life-threatening

hematoma.

Embolization First described in 1960 by Luessenhope and

Spence A rapidly evolving technique Embolic agent: histoacryl with lipiodol,

onyx... Complete obliteration by embolization alone:

40-60% AVM Multiple sessions are required most of cases AVM aneurysm.

Aims of embolization

Curative embolization Palliative embolization Partial embolization Pre-operation embolization Pre-radio surgery embolization

Complication

Incomplete embolization Intracranial hemorrhage Ischemia Gluing of micro catheter Perfusion pressure breakthrough

Radiosurgery

AMVs are inoperable Deep AVMs Diffusion AVMs

Tool for treatment: pros and cons

Embolization Surgery Radiosurg

Low procedural invasivity

2 1 3

Occlusion capacity 1-2 3 2

Speed of efficacy 2-3 3 1

Long-term reliability 2-3 3 3

Independent from size 3 2 1

Independent from brain functionality

3 1 2

Independent from angio-archi

1 2 3

Independent from flow 1 3 2

Thanks for your attention!

General recommendationSM grade Deep perfo

vesselSize 1st choice 2nd choice

1 and 2 Sx Rx

3 Absent Sx Rx

3 Present < 3 cm Rx Px

3 Present >3 cm Px Rx + Ex

4 and 5 Absent Ex + Sx Px

4 and 5 Present Px Rx + Ex