Arterio-Venous Malformations (AVM) of Brain

Dhaval ShuklaAdditional Professor of Neurosurgery

NIMHANS, Bangalore

Normal Blood Vessels

Abnormal Connection of Blood Vessels

AVM

Cause of AVM

• Not known

• Usually congenital

• Not hereditary

• Most AVMs do not grow or change in size

– Blood vessels may increase in diameter

– AVMs shrink due to clots in parts of an AVM

– AVMs may enlarge due to redirection of blood flow

Epidemiology

• Less than one percent of the general

population

• One in 200–500 people may have an AVM

• More common in males than females

Sites

Symptoms

• Symptoms may vary with location

• More than 50 % present with brain hemorrhage

• 20% - 25% with seizures

• Localized headache

• 15% may have difficulty with movement, speech

and vision

Brain hemorrhage

• Abnormal and “weakened” blood vessels over time eventually burst from the high pressure of blood flow from the arteries

• 1–3 % chance per year of bleeding

• Risk of bleeding = 105 – age (in years)

Brain hemorrhage

• 10–15% risk of death

• Loss of normal function– Temporary – Permanent: 20–30%

• Brain damage depends on – Amount of blood – Site of bleed

Symptoms of hemorrhage

Rebleeding risk

• More during first year after initial bleeding

– 6% to 18%

• Higher in the first year after the second bleed

– 25%

• Higher risk of bleeding in ages 11 – 35 years

Diagnosis

• Computed tomography (CT)– Hemorrhage

• Magnetic resonance imaging (MRI) – Location and size

CT scans showing hemorrhage due to AVM

MRI of AVM

Diagnosis

• Cerebral angiogram (DSA) – Required for treatment– Insertion of a catheter (small tube)

through an artery in leg to each vessels going to brain

– Injection of contrast material (dye)– Taking pictures of all blood vessels

of brain

Treatment

• Bleed

• Easily accessible

• Not too large

Medical Therapy

• Avoid

– Any activities that may excessively elevate blood

pressure

– Blood thinning drugs like warfarin

• Regular checkups with a neurologist

• Antiepileptic drugs

Surgery

Indications

• Bleeding

• Easily accessible

• Small or medium

Stereotactic radiosurgery(Gamma Knife)

Indications• Small• Difficult to reach by surgeryMechanism• Produce direct damage to the vessels

that will cause a scar and allow the AVM to “clot off”

• Takes 2 years to cure AVM

Endovascular treatmentIndications• Usually for a part of AVM

• Rest of AVM requires treatment either with surgery or Gamma Knife

• Occasionally for small AVMMechanism• Blocking off abnormal blood vessels to stop blood

flowing to AVM– Liquid tissue adhesives (glues)– Coils– Particles and other materials used

Endovascular treatment

Outcome – Surgery

• Small AVMs– Cure: 94 to 100%– Morbidity and mortality: <10%

– Bleeding– Infection– Paralysis or loss of function (temporary or permanent)– Convulsions (controllable or uncontrollable) – Coma (reversible or irreversible)– Death

– Seizure-free: 81%

• Large AVMs– Morbidity and mortality: 25%

Outcome – Gamma Knife

• Cure: 61% to 87% (after 2 years)

• Morbidity (during 2years): 1 to 36%

• Mortality (during 2years): 0 to 9%

• Seizure-free: 43%

Outcome – Endovascular treatment

• Cure: 5 to 40%

• Morbidity rates: 8% -10%

– Same as for surgery

• Mortality rate: 1%

• Seizure-free: 50%

Conclusion

• AVMs are difficult to treat and treatment decision should be individualized

• If AVM has not ruptured (never bled) there is no need of specific treatment. • Patient requires only symptomatic treatment

• Whenever possible microsurgery is the best option

• Gamma Knife is an optional treatment for inaccessible AVM

• Endovascular treatment is not effective as stand alone for most cases

• Medium size AVMs require multimodal treatment

• Very large AVMs should not be treated