Chapter 7: Vascular Malformations

Question 1

What are the two major groups of vascular anomalies?

Answer 1

Vascular malformations

and

vascular hemangiomas

Question 2

Most of cerebral vascular malformations are _____ and represent morphogenetic errors affecting arteries, capillaries, veins, or a compination of theses elements.

Answer 2

Congenital lesions

Question 3

Development of the human fetal vascular system occurs via two related processes. Which are?

Answer 3

Vasculogenesis and angiogenesis

Question 4

In this process, capillary-like tubes develop first and constitute the primary vascular plexus.

Answer 4

Vasculogenesis.

This primary capillary network is subsequently remodeled into large-caliber vessels (arteries, veins) and small capillaries.

Question 5

This process is regulated by a number of intercell signaling and growth factors.

Answer 5

Angiogenesis.

Mutations in various components of the angiogenetic system have been implicated in the development of various CVMs.

Question 6

Cerebral vascular malformations have been traditionally classified by histopathology into four major types. Which are?

Answer 6

1. AVM
2. Venous angiomas (developmental venous anomalies)
3. Capillary telangiectasis (sometimes simply termed “telangiectasis” or “telangiectasis”
4. Cavernous malformation

Question 7

Many interventional neuroradiologists and neurosurgeons group CVMs by function, not histopathology.

In this functional classification, CVMS are divided into two basic categories. Which are?

Answer 7

1. CVMs that display arteriovenous shunting

2. CVMs without arteriovenous shunting.

Question 8

Functional classification of CVM that are potentially amenable to endovascular intervention.

Answer 8

CVMs that display arteriovenous shunting

Question 9

Functional classification of CVM that are treated surgically or left alone.

Answer 9

CVMs without arteriovenous shunting.

Question 10

This malformation is a tightly packed “snarl” or “tagle” of serpinous, thin-walled vessels without an intervening capillary bed.

Answer 10

Arteriovenous malformation.

Question 11

Etiology of arteriovenous malformation

Answer 11

AVMs are congenital defects of vascular development characterized by dysregularted angiogenesis.

*Endothelial cells in cerebral AVMs express (GLUT1 (a protein in the embryonic microvasculature), matrix metalloproteinases, proangiogeneic growth factors, such as vascular endothelial growth factor (VEGF). This results in “downstream” derangements in vascular function and integrity.

Question 12

Most AVMs are _____.

a. solitary
b. multiple

Answer 12

A. Solitary

Question 13

Multiple AVMs are almost always _____.

a. Confined intracranially
b. Syndromic

Answer 13

B. Syndromic

Question 14

What are examples of syndromic types of AVMs?

Answer 14

Hereditary hemorrhagic telangiectasia (AKA as Rendu-Osler-Weber disease)

and

Capillary malformation-arterveionous malformation

Question 15

85% of AVMs are located where?

Answer 15

Supratentorial, located in the cerebral hemispheres.

15% are found in the posterior fossa.

Question 16

Most sizes of AVMS.

Answer 16

Most are intermediate in size with a nidus ranging from 2 - 6 cm in diameter.

AVMs vary from tiny lesions to giant malfromations athat can occupy an entery cerebral lobe or hemisphere.

Both feeding arteries and draining veins are usually enlarged.

Question 17

“Micro” - AVM hhave a nidus of how many cm?

Answer 17

Equal or less than 1 cm.

Feeding arteries and draining veins are usually normal in size.

Micro-AVMs are typically associated with HHT.

Question 18

Almost all multiple AVMs are associate with ______.

Answer 18

Vascular neurocutaneous sundromes

Less thatn 2% of all brain AVMs are multiple.

Question 19

What are the 3 components of AVM?

Answer 19

1. Feeding arteries
2. Nidus (center)
3. Draining veins

Question 20

What are the microscopic features of AVM?

Answer 20

1. Dysplastic thin-walled vessels
2. Ectatic “arterialized” veins
3. Only nonfunctional gliotic brain in nidus

Mural calcification and perivascular inflammatory changes may be present.

Question 21

True or False.

There are no capillaries and no normal brain parenchyma within an AVM nidus.

Answer 21

True.

Instead, varying amounts of laminated thrombus. dystrophic calcification, and hemorrhagic residua are often present.

Samll amounts of brain parenchyma within the nidus are occasionally identified but are typically gliotic and nonfunctional.

Question 22

What is the most common presentation of AVM?

Answer 22

Headache with parenchymal hemorrhage (ICH) = 50%.

Seizure and focal neurologic deficits are the initial symptoms in 25% each.

Question 23

Several grading sustems have been devised to characterize AVMs and estimate the risk of surgery.
What is the most widely used scale?

Answer 23

Spetzler-Martin scale

Question 24

What are other imaging findings associated with hemorrhage risk?

Answer 24

1. Evidence of previous hemorrhage.
2. Presence of an intranidal aneurysm
3. Stenosis or thrombosis of one or more “outlet” draining veins

Question 25

What are the treatment options for AVMs?

Answer 25

Embolization, surgery, stereotactic radiosurgery, or a combination of treatments are all current options in treating ruptured (hemorrhage) BAVMs.

Question 26

imaging diagnosis of an uncomplicated AVM is relatively straightforward. Except in what cases?

Answer 26

Presence of hemorrhage or thrombosis can complicate its appearance.

Acute hemorrhage may obliterate any typical findings of an AVM.

Residua of previous hemorrahgic episodese such as dystrophic calcification, gliosis, and blood in different stages of degredation may also complicate its appearance.

Question 27

CT findings of AVMs

Answer 27

Resemble a “bag of worms” formed by tightly packed tangle of vessels with little or no mass effect on adjacent brain.

NECT - show numerous well-delineated, slightly hyperdense serpentine vessels.
Calcification is common.

Enhancement of all three AVM components is typically intense and unifrom on CECT scans.

Question 28

MR findings of AVMs

Answer 28

Findings vary with vascular hemodynamics, the