PERSISTANT PRIMITIVE TRIGEMINAL ARTERY WITH VERTEBRO-BASILAR HYPOPLASIA WITH VERTEBRO-BASILAR INSUFFICIENCY- A CASE REPORT.

Persistent primitive trigeminal artery (PPTA) is one of the persistent carotid – vertebro-basilar anastomosis. It is usually unilateral and seen in 0.1 – 0.6 % of cerebral angiograms. It is associated with other anomalies like ectasia and fenestration of the ACA, absence of CCA, absence of both ICAs, hypoplastic basilar artery and vertebral arteries, bilateral occlusion of vertebral arteries, primitive otic artery, intracranial aneurysms at circle of Willis, carotid cavernous fistula, miscellaneous conditions like NF1, Klippel Feil syndrome, Moya-Moya disease, supratentorial and infratentorial AVMs. It can present as vertebra-basilar insufficiency due to steal phenomenon and due to micro emboli originating from atherosclerotic carotid artery which travel via PPTA to posterior circulation. We present cases of PPTA causing vertebro-basilar insufficiency with cerebellar signs due to steal phenomenon and flattening of ventral surface of pons on left side due to long standing pulsations of PPTA, and pontine infarct. Striking finding in one of our case is agenetic appearance of bilateral vertebral arteries in intracranial portion along with proximal two third of basilar artery.