Extracranial Vertebral Artery Dissection

KEY FACTS

TERMINOLOGY

• Vertebral artery (VA) dissection

• Irregularity of VA contour from intimal tear or

subadventitial hematoma

IMAGING

• Stenoocclusive dissection

○ Dissection to subintimal plane with vessel luminal

narrowing or occlusion

• Dissecting aneurysm

○ Dissection into subadventitial plane with dilatation of

outer wall

• Intramural hematoma is pathognomonic

○ Best seen as bright crescent on T1 FS MR

• CTA source images show contour changes of lumen

• Conventional angiography is gold standard

TOP DIFFERENTIAL DIAGNOSES

• Extracranial atherosclerosis

• Fibromuscular dysplasia

• Miscellaneous vasculitis

• Congenital VA hypoplasia

PATHOLOGY

• Traumatic VA dissection

○ Direct or indirect arterial injury

• Spontaneous VA dissection

○ Many associations and predisposing factors

CLINICAL ISSUES

• Age: Adults < 45 years

DIAGNOSTIC CHECKLIST

• Check other vessels carefully for 2nd dissection

• Subadvential/intramural hematoma can sometimes occur

without narrowing vessel lumen

• Cerebellar infarction in young to middle-aged adults; need

to exclude posterior inferior cerebellar artery infarction due

to VA dissection

(Left) Axial CECT in a patient

with idiopathic vertebral

artery dissection

demonstrates normal caliber

of left vertebral artery ſt and

narrowed, eccentric lumen of

right vertebral artery ﬇. Note

normal and symmetric

foramina transversarium.

(Right) Axial T1 FS MR in the

same patient reveals a

hyperintense crescent of

mural hematoma ﬇ with

small hypointense patent

lumen. Contralateral vertebral

artery shows no

methemoglobin hyperintensity

ſt. This is unilateral vertebral

artery dissection.

(Left) Axial CTA shows rim

enhancement of the left

vertebral artery st with lowdensity mural hematoma and

contrast filling the narrowed

lumen ſt. Subtle linear

lucency in the right vertebral

artery proved not to be a

dissection flap ﬈. (Right)

Axial T2 MR in a patient with

neck trauma and cervical

fractures reveals traumatic

vertebral artery dissection as

loss of right vertebral flow

void ſt, compared with the

normal left side st. Note right

cervical hemicord

hyperintensity from cord

ischemia ﬇.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

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