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Atherosclerotic Vascular Disease (ASVD) Fusiform Aneurysm

KEY FACTS

TERMINOLOGY

• Atherosclerotic vascular disease fusiform aneurysm (ASVD

FA)

• ASVD → abnormal dilation, tortuosity of intracranial arteries

• Aneurysms with separate inflow, outflow ostia

IMAGING

• Exaggerated arterial ectasia(s) + focal fusiform/saccular

enlargement

○ Long segment irregular fusiform or ovoid arterial

dilatation

○ Usually large (> 2.5 cm), may be giant

○ Vertebrobasilar > carotid circulation

• CT: Hyperdense, Ca++ common

• MR: Signal varies flow, presence/age of hematoma

○ Lumen, intramural clot often heterogeneous

○ Residual lumen enhances; intramural clot does not

○ Prominent phase artifact common

• Noncontrast 3D TOF inadequate due to flow saturation,

phase dispersion

• Dynamic contrast-enhanced MRA for aneurysm delineation,

T2 for brainstem delineation

CLINICAL ISSUES

• Peak age: 7th to 8th decades

• Presentation: Ischemic stroke > compressive symptoms

(cranial neuropathy)

• Unlike saccular aneurysms, rupture with subarachnoid

hemorrhage and headache rare

DIAGNOSTIC CHECKLIST

• DSA or contrast-enhanced CTA/MRA necessary to delineate

patent lumen

• Slow/complex flow in residual lumen → heterogeneous

signal

• Consider dissecting aneurysm, non-ASVD etiology if

younger patient

(Left) Autopsy shows a

tortuous vertebrobasilar

artery with an atherosclerotic

vascular disease (AVD)

fusiform aneurysm that

extends from the vertebral

artery junction ﬈ to the distal

basilar bifurcation ﬇.

(Courtesy R. Hewlett, MD.)

(Right) Oblique DSA in same

patient 2 yr later shows

dolichoectasia of the proximal

distal vertebral arteries ﬈. A

fusiform ASVD aneurysm lies

between the arterial ectasias;

residual lumen is indicated ﬉,

and aneurysm had enlarged

but partially thrombosed,

leading to mild TIAs.

(Left) NECT scan shows typical

hyperdense atherosclerotic

fusiform aneurysm ﬊ with

mural calcifications ﬈. Note

extensive calcification of the

internal carotid, right middle

cerebral arteries ﬉. (Right)

Series of MRs shows the

bizarre appearance of classic

atherosclerotic fusiform

vertebrobasilar aneurysm ſt.

(Courtesy M. Hartel, MD.)

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

115