This document discusses cerebrovascular malformations (CVMs) of the brain. It describes that CVMs are disorders representing morphogenetic errors affecting brain arteries, capillaries or veins. It classifies CVMs into two main groups - vascular malformations and hemangiomas. Pial arteriovenous malformations (AVMs) are specifically discussed. Pial AVMs have direct connections between arteries and veins without an intervening capillary bed. They contain enlarged feeding arteries, a nidus of tangled vascular channels, and dilated draining veins. Imaging findings on CT, MRI and cerebral angiography are provided to identify the key components of pial AVMs. Differential diagnoses and clinical management are also reviewed.
2. Vascular Malformations in Brain
OVERVIEW
Cerebrovascular malformations (CVMs) are a
heterogenous group of disorders that represent
morphogenetic errors affecting arteries, capillaries,
veins or various combinations of vessels.
3. Using accurate terminology
2 major groups:
A. Vascular malformations
Includes AVM & Fistula
B. Hemangiomas
These are benign vascular neoplasms, not malformations
Proliferating, mesenchymal, nonmeningothelial tumors
Can be capillary or cavernous
6. B. Functional classification
Endovascular radiologists have proposed a functional,
highly practical system, and divides all CVMs in 2
categories
CVMs that display shunting
AVM
Fistula
CVMs without AV shunting
Everything else
i.e. venous, capillary, cavernous malformations.
The 1st group are amenable to intervention & latter are either left
alone or treated surgically.
7.
8. Pial AVM
• Also called Cerebral AVM/ Classic AVM
• Definition
• It is a vascular malformation with direct artery to vein (AV)
shunting, no intervening capillary bed
• 3 components
• Enlarged feeding arteries, 1 or more
• Nidus of tightly packed, enlarged tangled vascular channels
• Dilated draining veins, 1 or more
**No normal brain parenchyma in between
9.
10.
11. Demographics
Age
Peak presentation: 20-40 years
Gender
M=F
Epidemiology
Prevalence: 0.040 - 0.52%
12. Location
Supratentorial – 85%
Posterior fossa – 15%
Number
Solitary
Multiple AVMs usually syndromic
(Hereditary hemorrhagic telangiectasia,
Wyburn-Mason syndrome).
Size
Varies from microscopic to giant
Most symptomatic AVMs are 3-6 cm.
13. Pathology
Etiology
Origin of AVMs remain uncertain
However, thought to occur congenitally, due to dysregulated
angiogenesis.
Genetic
Sporadic AVMs have up/down-regulated genes
Homeobox genes, such as HOXD3 AND HOXB3
Pleomorphisms on p21 locus of chromosome 9
Syndromic
Hereditary hemorrhagic telangiectasia
Wyburn-Mason syndrome
14. Clinical presentation
Headache
Seizure
Focal neurological deficit
Hemorrhage
Parenchymal/subarachnoid/intraventricular
Ischaemic events due to vascular steal from normal
brain
Incidental finding
22. MR findings
T1WI
Tightly packed mass, “honeycomb” of flow voids
Signal varies with flow rate, presence/age of hemorrhage
T2WI
Tangle of serpiginous, ‘honeycomb’ of flow voids
Little/no brain inside nidus
Some gliotic high signal may be present
FLAIR
Flow voids with surrounding high signal (gliosis)
T2*GRE
Blooming if hemorrhage
Post Contrast T1
Strong enhancement of nidus, draining veins
Rapid flow may not enhance arteries, and seen as flow voids
MRA
Helpful for gross depiction of flow
Does note depict detailed angioarchitecture
42. Dural AV fistula
AV shunts within wall of patent+- partially
thrombosed dural venous sinus, parallel venous
channel, or adjacent cortical vein.
Most common location = transverse/sigmoid sinus
(35-40%)
Differentiate from pial AVM by
Nidus intimately related to dural venous sinus
Predominant blood supply is from dural(meningeal)
arteries>> pial artery
Flow-related aneurysm are rare.
43. Case of AV fistula
60 yrs. Old female
with complaints of sudden severe
headache
49. Glioblastoma with AV shunting
GBM enhances
Has mass effect
Some brain parenchyma between vessels.
50. Key points
Hemangiomas are benign vascular neoplasms, not vascular
malformations
Pial AVMs have direct artery to vein shunting, no
intervening capillary bed
AVM has 3 components – feeding artery, nidus & draining
veins
Calcification in 25-30% cases
No brain parenchyma
No/minimal mass effect
DSA best delineates angioarchitecture
Flow-related aneurysm in feeding artery & nidus should be
looked carefully
DD’s – Dural AV fistula
Glioblastoma with AV shunting