Vascular Malformations
- Arteriovenous
Malformation
– 20-40 years old (25% under 15 years of age), M=F
- Abnormal
collection of arteries and veins separated by gliotic brain parenchyma
- Risk of
hemorrhage is 3-4%/year
- Initial
hemorrhage carries 17% mortality and 30-40% morbidity
- 7.7 year
mean interval between episodes of hemorrhage
- Vasospasm
is a rare complication of hemorrhage
- 8% of
patients also have an associated aneurysm, generally on a feeding vessel
- Most
become symptomatic between 2nd and 4th decades
- Mode of
presentation is age dependent:
- Infants
present with cardiac failure (secondary to vascular shunting,
hydrocephalus
- Teens
present with chronic headaches, spontaneous hemorrhage, seizures
- Young
adults most often present with hemorrhage causing focal neurologic
deficit, although can present with headaches, seizures, focal symptoms
- Sturge-Weber
disease – “Port wine” stain in a cutaneous distribution of the
trigeminal nerve, associated with an underlying cortical AVM resulting
in hemiparesis, seizures and occasional mental retardation
- Account
for 10-15% of subarachnoid hemorrhages
- Location:
- 90%
supratentorial
- 10%
infratentorial
- Diagnosis:
- MRI
shows mixed intensity lesion with serpiginous flow voids
- Angiography
displays lesion
- Treatment:
- Primary
surgical excision
- Stereotactic
radiosurgery
- Requires
2 years for effect of radiation to obliterate the lesion
- 80-85%
display angiographic disappearance at 2 years
- Approximately
3% risk of symptomatic radiation necrosis
- Staged
embolization:
- Used
to decrease size of lesion to make surgery or radiosurgery possible
- Rarely
curative by itself
- Cavernous
Malformation
– endothelial lined sinusoids
- Middle
age, F=M, most supratentorial, 10% multiple
- Contain
hemosiderin due to repeated hemorrhage
- Only
malformation without intervening normal brain
- Abnormal
collection of tightly packed sinusoidal vessels without intervening brain
parenchyma
- Four
typical modes of clinical presentation:
- Seizure
- Headaches
- Hemorrhage
and focal neurological deficit
- Incidental
finding on imaging in asymptomatic patient
- Risk of
hemorrhage is <1%/year except in 3% per year for first two years after
initial rupture, but hemorrhage is rarely catastrophic
- Lesions
tend to enlarge over time by repeated small hemorrhages
- Diagnosis:
- MRI shows
area of rings of alternating intensity (hemosiderin from repeated
microrupture)
- Angiography
is normal
- Appear
mulberry-like and are frequently calcified
- Treatment:
Surgical excision (especially if evidence of previous hemorrhage);
sometimes will cure associated epilepsy
- Capillary
telangiectasia – 2nd most common, found in white matter
- No
smooth muscle or elastic layer
- Associated
with Rendu-Osler-Weber disease
- Do not
hemorrhage (no hemosiderin)
- Venous
malformation
– most common
- 30%
associated with cavernous malformation
- multiple
with blue rubber nevus syndrome
- Anomalous
veins separated by normal brain parenchyma
- Most
common vascular anomaly found in autopsy and MRI studies
- Usually
located in deep white matter
- Diagnosis:
Angiography reveals radially configured structure in the venous phase
with no arterial input (“caput medusa”)
- Rarely
hemorrhage or cause clinical symptoms
- Surgical
resection is not indicated and may cause venous infarction since these
lesions frequently drain viable brain tissue