Vascular Lesions of the Brain

22 APRIL 2014

Contents

AVMs Dural AVF CCF Cavernoma Capillary telengiectasia Venous angioma Aneurysm Moya-moya Sturge–Weber Syndrome Vein of Galen malformation Dissection of Carotid and Vertebral Arteries Cerebral Venous Thrombosis

AVMs

True arteriovenous malformations (AVM’s) are characterised by the absence of a capillary bed and thus the presence of a high-flow arteriovenous shunt

It accounts for approximately 2% of all haemorrhagic strokes; These entity tends to occur in younger patients

Hospital based autopsy studies have reflected prevalence rates of up to 600 per 100,000 persons.

It was generally agreed that the incidence rates for AVMs are about 1 per 100,000 person years.

AVMs

Brain parenchyma may be found between the vessels depending on the size of the AVM nidus, A diffuse nidus is more likely to have cerebral

parenchyma within it compared to a tight nidus. The most common modes of presentation:

Haemorrhage The most common presentation and occurs in 50-65% of

patients The risk of AVM haemorrhage has been calculated to be

between to 2 to 4% per year The location of haemorrhage can be either primarily

intraparenchymal (lobar), subarachnoid, intraventricular or any combination of the above.

AVMs Seizures

occur in 30% of patients Generalised seizures or partial seizures with secondary

generalisation. Higher risk of seizure if the size of the nidus >6cm

Headache 11 to 14% Benign headache (same side of the lesion and is usually

non-pulsating) The evidence of a sentinel intracerebral haemorrhage.

Focal Neurological Deficit less than 10% deficits may be transient, persistent or sometimes

progressive. The incidence of aneurysms in relationship to AVM’s is 10-25%

AVMs: Imaging Modalities

Computed Tomography (CT) Atypical pattern of the haemorrhage Calcification of AVM vessels Intravenous contrast may show a serpiginous area of

enhancement CT Angiography (CTA)

Evaluation of the cerebral vasculature 3 dimensional imaging

AVMs: Imaging Modalities

Magnetic Resonance Imaging (MRI) Evaluation of the nidus size and its anatomical relationship, with MR

angiography (MRA) MRI’s are best used to identify high flow AVM’s as they show up as

signal voids due to the rapidly flowing blood. Functional MR imaging (fMRI) has resulted in the merger of anatomic

and functional detail allowing for significantly improved pre-operative planning.

AVMs: Imaging Modalities Digital Subtraction Angiography (DSA)

Gold standard modality in the imaging of AVM’s. It has a high spatial (0.2mm) and temporal resolution

(up to 24 frames/s) when compared to other modalities

It is the best modality in assessing the dynamic flow of AVM’s as the speed of contrast passing through the AVM allows us to assess it as a high or low flow shunt.

Accurate detection of intranidal aneurysms Invasive technique

Neurological complications (0.3%) Groin haematomas (6.9 to 8.1%)

AVMs: Treatment 3 main methods include:

Microsurgical resection, Stereotactic radiosurgery and Cerebral embolisation.

Treatment method based on the classification of AVM’s. Widely used grading methods for AVM’s

is the Spetzler-Martin classification

Spetzler-Martin classificationSpetzler-Martin classification

Dural Arterio-Venous Fistula (d AVF) DAVFs account for 10–15% of all intracranial

vascular malformations. The fistulas are more frequent among middle-

aged and older patients, though younger patients and children can be affected.

DAVFs consist of a shunt between dural arteries and sinuses, either directly or mediated by cortical or other sinusal veins.

DAVF is considered to be an acquired pathology.

DAVFs are preceded by thrombosis of a sinus. When the lumen recanalizes, microscopic AV

shunts, normally present within the wall of the sinus, may enlarge and open into the sinus.

Dural Arterio-Venous Fistula (d AVF) Many DAVFs remain asymptomatic or

have a benign course. In other cases, DAVFs can have a more

aggressive course, characterized by cranial nerve palsy, ischemia, hemorrhage, and cognitive disorders.

Symptoms are related to the location of fistula with its connecting veins and venous hypertension.

Venous connections could be either or both at cortical and epidural space. Cortical venous drainage might be the

cause of intracranial bleeding which is one of the most dangerous clinical manifestations.

If it goes into spinal veins, myelopathy will be observed.

Dural Arterio-Venous Fistula (d AVF) Imaging:

CT: Often normal without CE, engorged veins with CE

MRI & MRA: Numerous flow voids related to fistula or engorged veins

Cerebral Angiography: Gold standard for the diagnosis of dAVF. Sinus thrombosis with abnormal arteriovenous fistula

draining into dura or cortical veins, Corkscrew -like veins with venous hypertensions, enlarged feeding arteries from external carotid artery

Dural Arterio-Venous Fistula (d AVF) Treatment

Endovascular intervention: Feeding artery embolization, abnormal sinus

packing, Surgery:

Fistula resection, dura mater coagulation or resection

Radiosurgery: Focal irradiation

Carotid–Cavernous Fistulas

These are the most frequent type of arteriovenous fistulas and are characterized by a direct shunt between the intracavernous segment of the internal carotid artery (ICA) and the surrounding venous plexus of the cavernous sinus.

The pathogenesis is commonly a rupture of the artery and vein, after a penetrating or blunt trauma.

Spontaneous fistulas can occur: these are commonly due to a rupture of an intracavernous aneurysm, frequently linked to an associated angiodysplasia: fibromuscular dysplasia (FMD), neurofibromatosis, and Ehlers-Danlos syndrome.

Carotid–Cavernous Fistulas

Carotid-cavernous fistulas are characterized by a typical cavernous sinus syndrome with ophthalmoplegia, visus involvement, pulsating exophthalmos, chemosis, and bruit.

The symptoms can appear acutely or slowly, progressively days or weeks after the trauma.

Ischemia or intracerebral hemorrhage may occur.

Carotid–Cavernous Fistulas

Carotid–Cavernous Fistulas: Diagnosis and Treatment The dilated cavernous sinus and superior ophthalmic

vein can be easily recognized on CT or MRI. Angiography, however, is essential for a precise

diagnosis and in planning treatment. Carotid-cavernous fistulas are high-flow fistulas with a

rapid injection on the angiogram of the cavernous sinus. Depending on the location of the fistula and anatomical

variant, further drainage can be prevalently directed as follows: Anteriorly, in the superior inferior ophthalmic veins, in which the

flow is reversed; extracranially, draining into the facial vein system; or

Posteriorly, into the superior inferior petrosal sinuses.

Carotid–Cavernous Fistulas: Diagnosis and Treatment Through intercavernous anastomoses, the contralateral

cavernous sinus may be involved. Endovascular treatment with a detachable balloon to

occlude the shunt, which was proposed and developed by Serbinenko (1974) and Debrun et al. (1975), has progressively become the therapy of choice.

The treatment is performed today with a balloon or coils, which has led to good clinical and anatomical results, with limited morbidity and mortality

Cavernoma Cavernous malformations (CMs) are the second most

common vascular lesion encountered in the central nervous system (CNS) after venous developmental malformations (VDMs).

Cavernous malformations represent 5% to 16% of all CNS vascular

Based on large MR imaging and autopsy series, the overall incidence of CMs is approximately 0.4%-0.9%

CMs present in a sporadic and familial form. The annual bleeding rate in sporadic CMs is estimated at

0.25% to 6.5% per patient-year In familial form of CMs, the annual risk of hemorrhage

has been estimated at 13-17%

Cavernoma

Symptoms usually manifest between the 2nd and 5th decade, with the mean in the later 4th decade

A cavernous malformation has no intervening brain tissue and this characteristic separates it from the previously described vascular malformations.

Macroscopically they are well circumscribed and sometimes have a mulberry appearance.

Microscopically they are thin walled vascular channels with no intervening cerebral parenchyma.

Magnetic resonance with its special sequences, has allowed a more frequent detection of these lesions in both symptomatic patients, as well as in asymptomatic ones.

Cavernoma

CMs tend to grow through repetitive lesional hemorrhages, recanalization after intraluminal thrombosis and cavern proliferation

Hemosiderin deposits and gliotic reaction are found in the adjacent brain parenchyma.

Although a dilated vein may be found in proximity to the CMs, no abnormal feeding artery is seen.

Cavernoma: Imaging MRI is the diagnostic tool of choice for

accurate diagnosis of CMs. On MRI, CMs appear as a well defined,

lobulated lesion with a reticulated core of heterogenous signal intensity on T1 and T2 imaging sequences. The high intensity signal within the lesion is due to

the presence of hemoglobin degradation products such as methemoglobin and thrombosis.

Calcifications, fibrosis, acute and subacute blood may account for the low intensity signal within the lesion.

The mixed intensities have given CMs their typical popcorn appearance.

On T2WI and on gradient echo images, a peripheral ring of hypointensity can be seen, corresponding to the deposition of hemosiderin and ferritin on the outer limits of the lesion.

on contrast CT study of brain shows right frontal Cavernoma with punctate calcifications. An adjacent Gliosis noted. MRI study of brain shows right frontal Cavernoma appears to be complicated with bleed which has resolved and is evident by Gliosis with low signal intensity hemosiderin staining on GRE. 

Cavernoma: Imaging

Cavernoma: Imaging

Cavernoma: Management

Conservative management Asymptomatic cerebral CMs in the sporadic or familial form

are generally observed with follow-up MRIs performed at yearly or 2-year intervals.

Conservative management may also be recommended for patients with minimal symptoms

Stereotactic radiosurgery Alternative to surgery, especially in deep lesions. Its goal is to obliterate the caverns and thereby prevent

rebleeding. Studies have documented that the hemorrhage rate of CMs

decreases after a latency of about two to four years following radiosurgery

Cavernoma: Management

Surgical treatment Control of medically intractable epilepsy, recurrent

overt hemorrhage, and severe focal or progressive neurological deficits.

Not for asymptomatic patients, even for CMs located in an easily accessible region.

Capillary telangiectasia The Telangiectasias are similar to cavernous angiomas. Unlike the latter, there is brain parenchyma between the

vascular channels. The incidence on autopsy is reported to be 0.1–0.15% They are frequently associated with cavernous

angiomas, Telangiectasias can be found everywhere in the brain

parenchyma and spinal cord, with a predominance in the pons and basal ganglia.

The neuroradiological diagnosis is similar to that with cavernous angiomas.

Capillary telangiectasias are composed of vessels similar to normal capillaries with diameters usually less than 30 micrometres in diameter.

Capillary telangiectasia The vessel walls do not contain elastica and muscularis

and they are separated by normal brain tissue Hypointense on T1 MRI, hyperintense on T2 MRI,

somewhat contrast-enhancing ("blush") on a contrast MRI or a cerebral angiogram.

They do NOT have a hemosiderin ring (compare cavernomas and AVMs);

NOT associated with cerebral gliosis (compare AVMs) and do not exert any "mass effect" or pressure on the local brain.

They should be left alone unless they are convincingly growing (unlikely)

Stereotactic radiosurgery and open surgery should, in general, NOT be offered following the detection of these lesions.

Axial contrast-enhanced T1-weighted MRI demonstrates a subtle area of enhancement in the right parietal subcortical white matter in a patient with capillary telangiectasia (arrow).

Axial contrast-enhanced T1-weighted MRI obtained through the pons demonstrates an area of mild enhancement without mass effect in a patient with a capillary telangiectasia.

Venous angioma Developmental Venus anomaly (DVA)

also called venous angioma. DVA is prevalently located in the white

matter of the cerebral hemisphere, whereby several medullary veins converge on a unique collector draining further superficially in one of the sinuses or in one of the subependymal or basal veins.

Venous anomalies may represent a single dilated vein (varix) or multiple dilated venous channels.

They are also usually separated by normal brain tissue and there is no direct arterial input.

Venous angioma

Histologically they are endothelium surrounded by a single layer of fibromuscular tissue

DVA has been reported as being the most common vascular malformation detected on autopsy with an incidence of 2.6%.

Most DVAs are asymptomatic. Hemorrhages can occur, and these are considered to be

due to the associated cavernous angiomas (Cavernoma).

On an angiogram, typical DVAs are recognizable in the capillary–venous phases, where several medullary veins converge on a large collector

The arterial phase is normal.

Aneurysm Intracranial aneurysms are common

lesions in neurosurgical practice Prevalence in the general population

ranging from 0.2 to 9%. Descriptions of subarachnoid

hemorrhage (SAH) have been registered by a "sudden headache and stage of unconsciousness”.

The true incidence of aneurysmal SAH is not known but is estimated to be around 10/100.000/year.

This pathology is an important cause of mortality (50 to 60%) and morbidity (20% to 30%) in major series.

Risk factors for aneurysmal SAH

Aneurysmal rerupture has been associated with even poorer prognosis, with a mortality rate of 70 to 90%

The main risk factors for aneurysmal SAH are hypertension, smoking and alcoholism, however other factors can be also involved as shown below: 1. Cigarette smoking. 2. Hypertension. 3. Alcohol. 4. Slight increased risk with advancing age. 5. Cocaine abuse. 6. Oral contraceptives. 7. Pregnancy.

Signs and symptoms of SAH

Headache is the most common symptom (80%), classically described as “the worst headache of my life”, coming on suddenly and frequently accompanied by nausea and vomiting

Meningeal signs such as neck rigidity, Kernig and Brudzinski signs

Ocular fundus may reveal retinal and subhyaloid bleeding (20-40%), also recognized as Terson’s sign

Aneurysm Other signs and symptoms such as cranial nerves

dysfunction, motor and / or sensitive deficits can help in the determination of the site of the aneurysm, such as in those located at the posterior communicating artery which are often associated with third nerve palsy

Aneurysm: Diagnosis

The diagnosis of aneurysmal SAH is determined by a combination of clinical findings and alterations in the computerized tomography (CT), characterized by The presence of blood in the subarachnoid space and

sometimes located intracerebral or intraventricular However, in cases where blood is not shown on the CT

scan, it is mandatory to carry out a lumbar puncture (LP) for collection of cerebrospinal fluid (CSF) and to look for bloodstained CSF or xanthocromia.

Once SAH is identified, four vessel cerebral angiogram is mandatory to be performed

Aneurysm: Management

Aneurysms less than 3mm are micro-aneurysms and cannot be either coiled or clipped.

Treatment include: Clipping +/- clip reconstruction Endovascular Coiling +/- stent

assisted Coagulation and wrapping Bypass and trapping

Moya-moya

This is a chronic, progressive cerebrovascular disease, first described in Japanese patients by Takeuchi and Shimizu in 1957.

The term moyamoya, proposed by Suzuki and Takaku (1969), means “vague puff of smoke”, unique radiological findings shown in conventional angiography

Despite the fact that the disease is more frequent in Japanese patients, later studies showed that it can occur also in non-Asians.

Moya-moya Children and young patients are prevalently involved, but

the disease may also be seen in older patients. The two findings are indispensable

1) steno-occlusive change of the anterior part of the circle of Willis ring,

2) the development of the moyamoya vessels that are supposed to be the abnormally dilated collateral circulation to compensate the disturbance of main route of cerebral blood flow.

It is typically seen in both sides Intimal thickening due to proliferation and migration of

smooth muscle cells leads to progressive occlusion of the intracranial distal ICA, with extension also to the M1 and A1.

Moya-moya The etiology of the disease is not known. Moyamoya disease can occur in different pathological

conditions: Vasculitis with or without an autoimmune mechanism, Postirradiation state, Neurofibromatosis, Hemoglobinopathies, Atherosclerosis.

Genetic factors probably also play some role. Angiography is the essential method for identifying the

disease. Moyamoya disease has a progressive character, and it

leads to ischemic stroke and hemorrhage. The latter is frequently due to small aneurysms present

in the basal network.

Moya-moya: Treatment

2 ways of surgical revascularization: 1) direct bypass surgery 2) indirect bypass surgery

Direct bypass surgery means anastomosis between the superficial temporal artery (STA) and the cortical branch of the middle cerebral artery (MCA) or the anterior cerebral artery.

Moya-moya: Treatment

Indirect bypass surgery The temporal muscle and other vascularized tissue such

as the galea aponeurotica and periosteal membrane should be preserved without injury to the feeding arteries such as the STA, deep temporal artery and middle meningeal artery, covers the brain surface with these vascularized tissues.

It takes several months to develop the angiogenesis from these tissue to the brain surface.

These angiogenesis is not always constantly expected in all cases.

This indirect bypass surgery is more efficient in pediatric moyamoya cases

Sturge–Weber Syndrome(EncephalotrigeminalAngiomatosis) Sturge-Weber syndrome is a familial neurocutaneous

disease, characterized by a facial vascular nevus in the trigeminal distribution (facial port-wine stain), mainly in the first branch, a retinal angioma, and leptomeningeal angiomatosis.

The pathology consists of a network of thin-walled capillaries and venules lying between the pial and subarachnoid membrane.

There is also typically a paucity of cortical veins; this is responsible for the stasis and progressive hypoxia of the cortex, which becomes atrophic and partially calcified.

Sturge–Weber Syndrome(EncephalotrigeminalAngiomatosis) Children and teenagers with SWS often develop

neurologic problems including seizures, migraines, stroke-like episodes, learning difficulties or mental retardation, visual field cuts, and hemiparesis.

Any child with a facial port-wine stain in the V1 distribution, we recommend should have a head CT to image the calcification and an MRI of the brain with and without contrast to detect the angioma

The combination of the facial angioma and seizures are diagnostic.

The typical CT findings are cortical calcifications often in a gyral pattern and atrophy, although these findings may not be present in neonates or infants.

Sturge–Weber Syndrome(EncephalotrigeminalAngiomatosis) MRI with gadolinium contrast demonstrates the abnormal

intracranial vessels. The leptomeningeal angioma is typically ipsilateral to the

facial nevus. Bilateral brain lesions occur in at least 15% of patients. Hemispherectomy is the recommended treatment for

newborns with intractable seizures. The procedure improves seizure control and promotes better

intellectual development

Vein of Galen malformation

The pathogenesis of this malformation, which can be termed a true vascular malformation, is a malfunction in embryogenesis, involving the median prosencephalic vein (PV).

In accordance with the radioanatomical studies, the PV receives drainage from the deep cerebral structures and choroid plexus, and it drains further into the falcine sinus.

The vein disappears in a period between the sixth and eleventh weeks, and it is replaced by the vein of Galen, arising from unification of the caudal remnant of the PV with the developing internal cerebral vein.

The vein of Galen drains further into the straight sinus (SS).

Vein of Galen malformation

Failure of regression of the PV results in hypoplasia of the SS, with the venous drainage frequently diverted into a persistent falcine sinus

The cause of the abnormal arteriovenous shunts remains unknown.

The malformation may be linked to an embryogenetic error involving the choroidal arteries, which, in the same embryonic period when the PV is prominent, are the most active arterial structures present; thus, they are the most vulnerable to maldevelopment.

Vein of Galen malformation: Diagnosis and treatment CT and MR allow easy identification of this kind of

malformation. Selective and super-selective angiography is essential

for precise study. Angiographic study and endovascular treatment should

be performed earlier if rapid clinical deterioration, particularly as a result of heart failure, occurs.

Dissection of Carotidand Vertebral Arteries Spontaneous dissection is today a well-

recognized pathology that is responsible for stroke in many cases.

Its incidence is reported to be three to four cases per 100,000 persons yearly

Young and middle-aged patients are predominantly affected.

The lesion is characterized by a subintimal hemorrhage, leading to stenosis or occlusion of the artery.

The hemorrhage can involve the outer media or the subadventitial layer, resulting in the formation of pseudoaneurysms.

Dissection of Carotidand Vertebral Arteries Dissection occurs because of a primary intimal tear,

allowing the blood to pass into the arterial wall. Primary intramural hemorrhage can also occur through

rupture of the vasa vasorum. The pathogenesis of dissection can be traumatic, but in the

spontaneous form, the pathogenesis is not completely clear.

Structural changes of the arterial wall, associated with mechanical factors, are probably involved.

It is well known that dissection occurs frequently in patients with fibromuscular dysplasia (FMD), Ehlers-Danlos syndrome, Marfan syndrome, and lupus erythematosus

Dissection of Carotidand Vertebral Arteries Extracranial ICA: 2–3 cm distal to the bifurcation is the most

frequent site of dissection. The second-most frequent location is the extracranial

vertebral artery. Intracranial dissection is less frequent. Advanced age can be a factor, but there is a predominance of

young patients. The vertebrobasilar sector is more frequently affected. Dissection usually involves the first intracranial segment of the

VA, sometimes as an extension of extracranial dissection. Dissection of the basilar artery is less common: it can be

primary or a secondary extension of dissection of the VA.

Dissection of Carotidand Vertebral Arteries The treatment of extracranial lesions is controversial

since an important aspect is normalization of the vessel lumen in many cases.

This is particularly true when stenosis is present. Recanalization can also occur more rarely in cases of

occlusion. When a pseudoaneurysm is present, it commonly

remains unchanged or can enlarge later. In the acute phase, conservative medical therapy that

avoids intracranial embolism is preferred in many centers.

Dissection of Carotidand Vertebral Arteries Endovascular therapy may be performed later if the

stenosis or pseudoaneurysm remain. In selected cases, when stenosis is present but the

lumen is maintained and an embolic intracranial occlusion is recognizable, selective endovascular thrombolysis can be performed.

Cerebral Venous Thrombosis The true incidence of central venous thrombosis (CVT)

remains unknown. Causes

infection, Intracranial extension of infectious diseases

involving the skin-bone cavities of the craniofacial area

General bacterial septicemia or viral infection, especially due to HIV and cytomegalovirus.

During pregnancy, In puerperium, Usage of oral contraceptives.

Cerebral Venous Thrombosis Causes

Pathologies of the red blood cells, such as thrombophilia, polycythemia, sickle cell disease, leukemia, and lymphoma, and in many coagulation disorders, such as protein C and S deficiency and disseminated intravascular coagulation.

Behçet’s disease, Systemic lupus erythematosus, Severe dehydration and cardiac failure. Cranial trauma and neurosurgical intervention. Intracranial tumors, especially meningiomas, can

involve the adjacent sinus and cause thrombosis

Cerebral Venous Thrombosis The superior sagittal sinus (SSS) is the venous channel

most commonly involved, followed by the transverse sinus.

The thrombosis can be limited to the sinus, and the clinical presentation may frequently be characterized by clinical symptoms owing to intracranial hypertension, such as headache and visual disturbances.

Cortical vein tributaries of the thrombosed sinus can be secondarily involved as a result of retrograde propagation of the thrombus, which commonly leads to ischemia.

Cerebral Venous Thrombosis CT and MRI allow the detection of changes to the brain

parenchyma in the form of hemorrhagic and/or nonhemorrhagic infarcts, uni- or bilateral, single or multiple, with various locations depending on the site and extension of the CVT.

White matter hypodensity on CT and hyperintensity on T2 images on MRI, which indicate edema of a preceding venous infarct, is also a sign suggesting venous thrombosis.

On CT, an abnormal hyperdensity can be recognized at the level of the torcular herophili, SSS, and lateral sinus.

In doubtful cases, or whenever a more specific diagnosis is required, angiography remains a practical diagnostic method.

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