Persistent Primitive Hypoglossal Artery (PPHA) - A Rare Anomaly with Literature Review

Abstract

Persistent primitive hypoglossal artery (PPHA) is a rare embryonic carotid vertebrobasilar artery anastomosis. Hypoglossal artery arises from the internal carotid artery (ICA) between the C1 and C2 vertebral levels and traverses through the hypoglossal canal to join the vertebro-basilar system. We present a rare case of an anomalous right sided PPHA as a sole supply to posterior circulation of brain with absent/hypoplastic bilateral vertebral arteries in a two year child who had presented with acute left sided haemiplegia. Three dimensional time of flight magnetic resonance angiography identified an anomalous vessel arising from the right internal carotid artery at the level of axis vertebra and joining the vertebra-basilar arterial system after coursing through the right hypoglossal canal. This anomaly when present may predispose the person to aneurysm formation, ischaemia in the posterior circulation and atherosclerotic disease of the intracranial vessels.

Keywords: MR Angiography; Proatlantal intersegmental artery; Vertebro-basilar artery.

[Table/Fig-1]:

NECT SCAN – Fairly defined hypodense area in Right Capsulo-ganglionic region (White arrow)

[Table/Fig-2]:

Right capsulo-ganglionic chronic infarct – T1 hypointense and T2 hyperintense area inverting on FLAIR and showing no diffusion restriction on DWI sequence

[Table/Fig-3]:

3D TOF - MIP images in coronal :(A) and sagittal; (B) planes demonstrating an anomalous vessel(PPHA) arising from the cervical part of right internal carotid artery (ICA, red arrow in A) and forming basilar trunk with termination of posterior cerebral arteries (PCA). Bilateral vertebral arteries are absent. Source images in axial planes showing origin(C), course through the hypoglossal canal (arrow in D) and bifurcation into the PCA (arrow in E)

[Table/Fig-4]:

3D Surface shaded display (SSD) showing PPHA with absent bilateral vertebral arteries

[Table/Fig-5]:

Persistent carotid vertebro-basilar anastomoses from superior to inferior, trigeminal artery (black arrow), Otic artery (white arrow), Hypoglossal artery (curved white arrow) and Proatlantal artery (white arrow head) (“Used with permission from Amirsys, Inc")