Learning objectives
To recognize a rare association of persistent carotid vertebrobasilar anastomoses with aneurysms
To recognize the persistent carotid vertebrobasilar anastomoses and the vascular anatomy
Background
Persistent carotid-vertebrobasilar anastomoses represent variant anatomical arterial communications between the anterior and posterior circulation,
providing major blood supply to the posterior circulation.
Persistent trigeminal artery (PTA) and persistent hypoglossal artery (PHA) are the two most common types of the persistent embryonic anastomoses.
Findings and procedure details
Etiology and demographics
There are four persistent fetal anastomoses between the carotid and vertebrobasilar circulations.
These represent the non-obliterated remnants of the pre-segmental dorsal arteries which comprise the persistent primitive trigeminal artery (PPTA),
persistent hypoglossal artery (PHA),
persistent otic (acoustic) artery (POA) and the proatlantal intersegmental artery (PIA). These primitive carotid vertebrobasilar anastomoses occasionally persist into adulthood and may be incidentally detected on imaging [1].
In the early embryonic stage,
blood supply to the hindbrain is mainly via the 4 carotid-vertebrobasilar anastomoses.
These then regress...
Conclusion
The persistent primitive carotid vertebrobasilar anastomoses represent rare variant anatomical anastomoses between the anterior and posterior circulation.
When present,
these may provide majority of the vascular supply to the posterior circulation via the ICA.
On occasion,
these patients may present with concomitant aneurysms and thus may require operative or endovascular intervention.
Knowledge of the vascular anatomy and appropriate imaging work-up is thus necessary in patients with these persistent anastomoses as compromising the embryonic carotid-vertebrobasilar anastomoses may lead to potentially catastrophic ischemic outcomes.
References
O'uchi E,
O'uchi T.
Persistent primitive trigeminal arteries (PTA) and its variant (PTAV): analysis of 103 cases detected in 16,415 cases of MRA over 3 years.
Neuroradiology 2010;52(12):1111-9.
PMID: 20309534.
Dimmick S,
Faulder K.
Normal Variants of the Cerebral Circulation at Multidetector CT Angiography.
RadioGraphics 2009;29(4):1027-43.
PMID: 19605654.
Luh G,
Dean B,
Tomsick T,
Wallace R.
The persistent fetal carotid-vertebrobasilar anastomoses.
American Journal of Roentgenology 1999;172(5):1427-32.
PMID: 10227532.
Uchino A,
Sawada A,
Takase Y,
Kudo S.
MR Angiography of Anomalous Branches of the Internal Carotid...