brain aneurysms & av malformations

Brain Aneurysms

and

AV Malformations

Brain Circulation

Brain Circulation

Arterial Circulation in the Brain

Circle of Willis

Cerebral Arteries

Cerebral Angiography

Venous Drainage

Cerebral Spinal Fluid Drainage

Cerebral Spinal Fluid

Cerebral Spinal Fluid

The Human Brain

Aneurysm

• The word aneurysm comes from the Latin word aneurysma, which means dilatation.

Types of Aneurysms

• Saccular aneurysm– Occurs at bifurcations

• Fusiform aneurysm– Commonly in basilar

artery

• Dissecting aneurysm

• Ruptured aneurysm

Aneurysm Types

Saccular

Fusiform

Large Aneurysm

Cerebral Aneurysms• Cerebral aneurysms usually occur at the

bifurcations and branches of the large arteries located at the Circle of Willis.

• The most common sites include the:– Anterior Communicating artery (30 - 35%)

– Bifurcation of the Internal Carotid and Posterior Communicating artery

(30 - 35%)– Bifurcation of Middle cerebral (20%)– Basilar artery bifurcation (5%)– Remaining posterior circulation arteries (5%)

Risk Factors for Aneurysms

• Smoking• Hypertension• Polycystic kidney disease 15% have aneury• Coarctation of the aorta• Anomalous vessels• FMD• Connective tissue disorders (eg, Marfan,

Ehlers-Danlos)• High-flow states (eg, vascular malformations,

fistulae)• Spontaneous dissections/Trauma

Signs & Symptoms of Brain Aneurysms

• Usually asymptomatic until rupture

– Cranial Nerve Palsy

– Dilated Pupils

– Double Vision

– Pain Above and Behind Eye

– Localized Headache

“Warning Signs” of Brain Aneurysms

• Warning signs prior rupture

– Localized Headache

– Nausea & Vomiting

– Stiff Neck

– Blurred or Double Vision

– Sensitivity to Light (photophobia)

– Loss of Sensation

Treatment of Brain Aneurysms

• Surgery– craniotomy and clipping of aneurysm

• Endovascular coiling

Aneurysm Post-Op Risks• Rebleeding

– Most frequently within the first 24 hours– Up to 20% of patients rebleed within 14 days– Main preventative measure is control of blood pressure

(preferably beta blockers)

• Vasospasm– Usually occurs before 3 days or after 10 days (post bleed)– May require hyper-volemic therapy

• Hydrocephalus• Hyponatremia• Fluids / Electrolytes

Arterio-Venous Malformation

(AVM)• Arteriovenous malformation (AVM) of the brain is a

"short circuit“ between the arteries and veins.

• Normally the connection between arteries and veins is through a network of smaller vessels (capillaries) which slow the blood down and permit the exchange of food, oxygen and nutrients into the tissues.

• In arteriovenous malformations, the arteries and veins have a direct connection, bypassing the capillary network.

Arterio-Venous Malformation (AVM)

AVM

• Arteriovenous malformation of the brain presents later in childhood or, more frequently, in adults in the second to third decade of life.

• AVMs present with seizures, hemorrhage, progressive neurological dysfunction or headaches

Complications of AVM’s

• Hemorrhage (into surrounding tissue)

• Ischemia

• Seizures

• Brain Cell Death

Signs & Symptoms of AVM’s

• Seizures

• Headaches

• “Whooshing" Sound (bruit)

• Other Signs – Subtle behavioral changes – Communication or thinking disturbances – Loss of coordination and balance

– Paralysis or weakness in one part of the body – Visual disturbances – Abnormal sensations

Diagnosing AVM’s

• MRI (including MR Angiography) as well as CT Angiography are among the initial neuro-imaging tests that help identify these problems.

• Cerebral Angiography is a prerequisite to accurately and definitively identify the precise anatomy and configuration of both the lesion as well as the feeding and draining vessels

Treatment of AVM’s

• Surgery

– usually delayed

– open ligation and/or resection of the AVM

• Radiosurgery

• Embolization

– usually as adjunct to surgery

• Observation

Radiosurgery

• Believed to "work" by initiating an "inflammatory" response in the pathological blood vessels ultimately resulting in their progressive narrowing and ultimate closure

• The risk for hemorrhage is not reduced during this lag time

• There is the added risk of radiation necrosis of adjacent healthy brain tissue or brain cyst formation

Radiosurgery• Advantages:

– Noninvasive

– Can access all anatomic locations of the Brain

• Disadvantages:

– Can only treat smaller lesions (<3 cm in diameter)

– Requires 2 or more years to complete

AVM Post-Op Risks

• Perfusion-breakthrough bleeding

• Endovascular occlusion

Brain Aneurysms & AVM’s

• Patients with AVMs have an increased risk of developing an intracranial aneurysms

• Aneurysms are often found on arteries feeding the AVM.

Intracranial Hemorrhage (ICH)

• Epidural

• Subdural

• Subarachnoid

• Intraparencymal

• Intraventricular

• Cerebellar

Treatment of ICH

Two key concepts:1) Intracranial Pressure

– Elevated when ICP >20 mm Hg

2) Cerebral Perfusion Pressure– CPP = MAP - ICP– Must maintain CPP > 70 mm Hg– Example: MAP = 100, ICP = 20 CPP = 80 mmHg

Treatment of ICH• ICH is a dynamic, not a static process

• Hemorrhage volume can increase over time

• CT scan is the most important tool in your diagnostic toolbox

• Managing blood pressure is very important

• Must aggressively manage fever and seizures

• Consider hyperventilation and paralytics in setting of increased ICP and deterioration

Subarachnoid Hemorrhage (SAH)

• SAH may be spontaneous or traumatic

• Spontaneous SAH are caused by– Cerebral aneurysms

– AV malformations

• Uncommon causes – neoplasms, AVM’s, venous angiomas, infectious aneurysms

SAH• Warning bleeds” are relatively common

• Sentinel headache 30-50%

• Early diagnosis prior to rupture will improve outcomes

• Unusual headache

• 50% of patients die within 48 hours irrespective of therapy

SAH• Often accompanied by a

period of unconsciousness (50% never wake up)

• Common signs include neck stiffness, photophobia, headache

• 20% have ECG evidence of myocardial ischemia

Complications of SAH

• Hydrocephalus may develop within the first 24 hours because of obstruction of CSF outflow in the ventricular system by clotted blood.

• Rebleeding of SAH occurs in 20% of patients in the first 2 weeks. Peak incidence of rebleeding occurs the day after SAH. This may be from lysis of the aneurysmal clot.

• Vasospasm from arterial smooth muscle contraction (symptomatic in 36% of patients).

Hydrocephalus After SAH

• Caused by obstruction of CSF flow by clotted blood

• Must be careful with drainage – a reduction in ICP can increase the risk of rebleeding

Rebleeding After SAH

• Rebleeding occurs most frequently within the first 24 hours

• Up to 20% of patients rebleed within 14 days

• The main preventative measure is to control the blood pressure – preferably beta blockers

• Alternatively early clipping of the aneurysm allows hypertensive and hypervolemic therapy to prevent vasospasm

Vasospasm After SAH• Worst time is day 7 to day 10 (most

frequent time for vasospasms)

• Diagnosed by neurologic exam, transcranial doppler and angiography

• May use calcium channel blockers

– Reduce vasospasm, neurological deficit, cerebral infarction and mortality

• May use some antispasmodics

Vasospasm HHH Therapy

• Hemodilution– Hct 30-35%

• Hypertension– Phenylephrine /

Norepinephrine

– BP titration to CPP/exam

• Hypervolemia– Colloids/crystalloids

Other Vasospasm Therapy• Angioplasty

– BP management during procedure

– Reperfusion issues

– Timing

• Papaverine Infusion

– Side effects

– Repeated trips

Other Complications of SAH

• Neurologic deficits from cerebral ischemia, peaks at days 4-12.

• Hypothalamic dysfunction causes excessive sympathetic stimulation, which may lead to myocardial ischemia or labile detrimental BP.

• Hyponatremia may result from cerebral salt wasting / SIADH

• Nosocomial pneumonia and other complications of critical care may occur.

• Pulmonary edema – neurogenic & nonneurogenic

Treatment of SAH’s

1) Identifying and treating the causative lesion, thus preventing re-bleeding

2) Treating hydrocephalus

3) Treating and preventing vasospasm

Treatment of SAH’s

• Maintain systolic BP >130mmHg

– Use vasopressors if necessary to maintain CPP and reduce ischemic complications from vasospasm

• Generally avoid vasodilators (except calcium channel blockers)

Brain Hemorrhage

Sudden onset of “the worst headache of my life”

The End

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