Vertebrobasilar Dolichoectasia

Vertebrobasilar dolichoectasia (dilatative arteriopathy) refers to the elongation or widening of the intracranial vertebral and/or basilar arteries. The etiology is unclear, but is thought to be related to atherosclerosis and/or hypertension.

Also known as S-shaped aneurysm, megadolichobasilar anomaly, fusiform aneurysm, basilar artery ectasia, tortuous vertebrobasilar system, vertebrobasilar dolichoectasia is usually diagnosed subjectively. Research criteria have also been proposed and can be used to guide diagnosis. These include:

• Basilar artery diameter > 4.5 mm in any location along its course
• Basilar artery origin the level of the pontomedullary junction
• Basilar artery bifurcation above the suprasellar cistern
• Basilar artery lateral to the margin of the clivus or dorsum sellae
• Basilar artery with lateral deviation > 10 mm perpendicular to a straight line joining its origin to its bifurcation
  
  
• Vertebral artery diameter > 4.0 mm along its intracranial course
• Vertebral artery above the level of the pontomedullary junction
• Vertebral artery > 10 mm perpendicular to a straight line joining its intracranial entry point to the basilar artery origin

Most cases of vertebrobasilar dolichoectasia are asymptomatic, but patients can present with cranial neuropathy (from cranial nerve compression), brainstem compression, hydrocephalus, and infarction.

Although vertebrobasilar dolichoectasia can be demonstrated on routine CT (as was the case presented here), MRI using high-resolution sequences (e.g., FIESTA, CISS) is the most sensitive techniques for determining the cause of cranial nerve symptoms.

The images above are from a cervical spine myelogram in an 80-year-old woman. Incidentally seen is ectasia and tortuosity of the vertebral artery with significant compression of the medulla.

References

• Tay KY, U-King-Im JM, Trivedi RA, Higgins NJ, Cross JJ, Davies JR, Weissberg PL, Antoun NM, Gillard JH. Imaging the vertebral artery. Eur Radiol. 2005 Jul;15(7):1329-43.
• Ubogu EE, Zaidat OO. Vertebrobasilar dolichoectasia diagnosed by magnetic resonance angiography and risk of stroke and death: a cohort study. J Neurol Neurosurg Psychiatry. 2004 Jan;75(1):22-6.