Authors: Anthony C. Wang
Khol D. Than
These photographs show the hypoglossal nerve traversing a fenestrated right vertebral artery, just proximal to the vertebrobasilar junction. The branching pattern is normal, with no aneurysms or arteriovenous malformations. Incidence of fenestration ranges from 0.23% to 1.95% for all vertebral/basilar arteries. Most fenestrations (>70%) are extracranial and occur at the C1-C2 level. Fenestration—which differs from duplication—is possibly a persistent segment of the embryonic hypoglossal or proatlantal intersegmental arteries. Most basilar fenestrations are in the proximal portion. Fenestrations are usually asymptomatic.
Megan E. B. Foldenauer, PhD, CMI
Holly A. Wagner, ELS