AVM is a congenital mal development of blood vessels with one or more direct communication between arterial and venous channels

Most common in cerebral hemispheres, frequently in MCA territory

Involves one or combination of Epi cerebal Trans cerebral Sub ependymal circulation

Incidence – 0.14% Presents usually at 40 years, no sex prelidiction Low peripheral resistance in avm high flow

volume progressive arterial enlargement

Haemorrhage: More common in small AVM due to high

pressure in feeding arteries Annual risk of haemorrhage – 2-4% Rebleed in 1st year – 6% Cumulative risk in 25 years – 53% Death from initial AVM rupture – 10% Neurological deficit – 50% with each

haemorrhage

Risk of bleeding [ atleast once]

expected years of remaining life

=1-(annual risk of not bleeding)

Seizures – common in large AVM bcos it involves cortex

Headache – 5-35% Raised ICP due to increased venous sinus

pressure Hydrocephalus due to SAH Intellectual deterioration

CT – For screening, serpentine veins seen , haemorrhage , calcification

MRI – relationship of AVM to surrounding brain, hypo in T1, flow voids, for MR assisted stereotactic navigation, Fmri + neuronavigation

CT angio better than conventional angio Look for – feeding arteries , passing arteries,

draining veins, steal, associated aneurysm in parent vessel/ intranidal

Grade = total points 1-5Grade 6 –inoperable or not amenable to any treatment modalityGood/ excellent surgical outcome with respect to SM grading [heros et al]

SM grade % 0f cases with good results with surgery

1 100

2 94

3 89

4 61

5 29

Resectability depends on SM grading, flow thru AVM [high/low], vascular steal

Surgical risk vs risk of bleeding Needs meticulous disection

Treatment options pros cons

Surgery Is the treatment of choice

1 Eliminates the risk of bleeding immediately2 Seizure control improves

1 Invasive2 Risks of surgery

SRS –For nidus less than 3cm, deep seated AVM

1 Out patient procedure2 Non invasive3 Gradual reduction of

AVM flow 4 No recovery period

1 Takes 1-2 years to work with risk of bleeding during that period2Not useful for large lesion

embolisation 1 Facilitates surgery/SRS

1 Inadequate by itself to obliterate AVM

2 Induces haemodynamic changes

3 May require multiple sitting

4 No effect on progression of neurological symptoms, seizure frequency

Obliteration rate is 80 – 85 % for small AVM RADIATION NECROSIS – 1% Haemorrhage after radiation- 10%

Onyx – used now Timing : 3-30 days before surgery, 30 days

before SRS RISK – death 1%, bleed – 3%, rebleed 7%, mild

deficit- 9%, NPPB

Grade 1& 2 surgery Grade 3-5 individualised planning, combination of 3 treatment

modalities