Persistent primitive hypoglossal artery associated with proximal posterior inferior cerebellar artery aneurysm.

Background: A persistent primitive hypoglossal artery (PPHA) is a rare anomaly. The association of PPHA with intracranial aneurysms of the artery has also been rarely reported. We surgically treated a case of PPHA associated with a ruptured saccular aneurysm at the proximal posterior inferior cerebellar artery (PICA).

Case Description: The patient was admitted because of subarachnoid hemorrhaging. Angiography and three-dimensional computed tomography (CT) angiography (3D-CTA) demonstrated a left PPHA entering the posterior fossa through the left large hypoglossal canal. The left vertebral artery was absent. A saccular aneurysm was found at the junction of the PPHA and the proximal PICA. 3D-CTA showed not only the aneurysm itself but also the anatomical relationship between the aneurysm and the surrounding structures. Therefore, 3D-CTA was very useful in planning the surgery. The neck of the aneurysm was clipped through a far lateral approach associated with a C1 laminectomy, because this case had a large posterior condylar emissary vein and the aneurysm was located just posteroinferior to the hypoglossal canal.

Conclusions: A case of PPHA associated with an aneurysm at the proximal PICA is reported. This case not only had a large hypoglossal canal but also had a huge posterior condylar emissary vein in the large posterior condylar canal. Anomalous structures associated with PPHA are also discussed. Finally, 3D-CTA proved to be very useful in planning the optimal surgical modality around the lateral portion of the foramen magnum.