Vascular Malformations (Stopped at cavernous malformations of Greenberg)

Question 1

What are the five major categories of vascular malformations?

Answer 1

(i) AVMs
(ii) Venous angiomas
(iii) Cavernous malformation
(iv) Capillary telangiectasia
(V) Direct fistula

Question 2

Characterize the flow and pressure through AVMs, is it high or low?

Answer 2

AVMs generally medium to high flow and high pressure

Question 3

What is the risk for bleeding per year in those with AVMs?

Answer 3

2-4%

Question 4

Anatomically describe AVMs

Answer 4

Dilated arteries and veins with dysplastic vessels and intervening capillary bed or neural parenchyma

Question 5

What are the two main treatment options used for AVMs?

Answer 5

Stereotactic radiosurgery (if > 3cm deep)
Surgical resection

Question 6

How do AVMs generally present? How does this compare to aneurysms?

Answer 6

Hemorrhage in about 50% (aneurysms present with hemorrhage in 92%)
Other presentations: seizure, ischemia (from steal), headache, mass effect, elevated ICP

Question 7

Where is the location in the majority of AVM ruptures?

Answer 7

Intraparenchymal (82%)

Question 8

What are anatomic/location-based risk factors for AVM rupture?

Answer 8

Deep nidus
Deep venous drainage
Size

Question 9

How often are aneurysms also identified in patients with AVMs?

Answer 9

7%

Question 10

What are the five categories of aneurysms associated with AVMs?

Answer 10

I: Aneurysm proximal and ipsilateral to AVM on feeding artery
IA: Aneurysm proximal and contralateral to AVM on feeding artery`
II: Aneurysm distal on superficial feeding artery
III: Aneurysm proximal or distal on deep feeding artery
IV: Aneurysm in unrelated location to AVM

Question 11

How will AVMs appear on T1 and T2 MRI?

Answer 11

Flow void (dark)

Question 12

What are the three components of the Spetzler-Martin grading scale of AVMs?

Answer 12

Size (< 3, 3-6, > 6)
Venous drainage
Eloquent regions

Question 13

What is the recommended management of SM grade 4 and 5 AVMs?

Answer 13

Angiograms every 5 years to look for outflow stenosis or feeding vessel aneurysms. Recommended not treating grade 5 AVMs and not surgery for grade 4 (maybe SRS for grade 4)

Question 14

SRS is best suited for AVMs with what characteristics?

What are pros and cons to use of SRS for AVMs?

Answer 14

Small nidus (< 2.5 - 3cm) and deep
Pros: Less invasive
Cons: Takes 1-3 yrs for gradual reduction of AVM to occur over which time there is continued risk of bleeding

Question 15

What is the third option for treatment of AVMs which is sometimes combined with surgery or SRS?

Answer 15

Endovascular embolization

Question 16

What is the primary agent used in embolization of AVMs?

Answer 16

Onyx (mix of ethylene-vinyl alcohol - EVOH - in dimethyl sulfoxide (DMSO). Has different types which are more or less viscous; e.g. Onyx-18, Onyx-34

Question 17

What is recommended preop medical mgmt for AVMs?

Answer 17

Propranolol or labetalol to minimize postop normal perfusion breakthrough which fmay facilitate hemorrhage or edema

Question 18

During AVM surgery should you occlude the feeding vein or artery first, why?

Answer 18

Artery. Occluding the veins first can lead to high pressure build-up and increased risk for hemorrhage

Question 19

If preop angiography demonstrates a high-flow AVM what may you want to do before booking the craniotomy?

Answer 19

Consider embolization because such high-flow AVMs are at increased risk of rupture

Question 20

Describe how occlusive hyperemia may occur as a delayed complication after AVM resection?

Answer 20

Occlusion of AVM feeding veins which may be outflow for adjacent normal brain leads to blood “backing up” causing hyperemia. This relative stasis of blood at normal adjacent regions may cause thrombosis at the draining vein or dural sinus.

Question 21

What are venous angiomas and characterize their level of flow and pressure?

Answer 21

Venous anomalies occurring isolated from arteries and having intervening brain present.
Low flow, low pressure

Question 22

Are venous angiomas often symptomatic?

Answer 22

Rarely. If they do present they may have seizures and less commonly hemorrhage

Question 23

In what locations are venous angiomas most common?

Answer 23

Areas supplied by MCA and by Great vein of Galen

Question 24

Venous angiomas may have associated _________ which is more likely to be the contributing symptomatic factor.

Answer 24

Cavernous malformations

Question 25

How do venous angiomas appear on angiograms?

Answer 25

Caput medusa (or starburst pattern, spokes on a wheel, umbrella, mushroom appearance, etc.)

Question 26

Should venous angiomas be treated?

Answer 26

No. The only reasons to treat are if their is bleeding or intractable seizures caused by them

Question 27

What are some reasons for vascular malformations to be “angiographically occult”?

Answer 27

(i) Sluggish flow
(ii) Small size
(iii) Hemorrhaged and bleeding has obliterated lesion or clot has compressed lesion
(iv) Angiogram films need to be later in phase due to late filling

Question 28

How do angiographically occult vascular malformations (AOVMs) typically present?

Answer 28

Seizures or headaches

Question 29

Osler-Weber-Rendu syndrome is also known as what?

What is inheritance?

Answer 29

Hereditary Hemorrhagic Telangiectasia (HHT)

Autosomal Dominant

Question 30

How does HHT present?

Answer 30

With AVMs, cavernous malformations, capillary telangiectasis, and/or pulmonary AV fisutals (increase risk for paradoxical emboli and cerebral abscess formation)