Unusual case of persistent primitive hypoglossal artery with anterior choroidal artery aneurysm in Chiari type I malformation

Persistent primitive hypoglossal artery (PPHA) is a rare form of persistent embryonic carotid-basilar anastomosis. We present an unusual case of PPHA and an anterior choroidal artery (AChoA) aneurysm associated with Chiari type I malformation. A 45-year-old woman presented with transient dizziness. Magnetic resonance imaging revealed Chiari type I malformation and a left AChoA aneurysm. Digital subtraction angiography incidentally revealed a left PPHA. To the best of our knowledge, this is the first reported case of Chiari malformation in conjunction with PPHA and aneurysms. In this case, the perfusion of the posterior circulation is completely dependent on PPHA. It is very important to identify such variant vessels and complex angioarchitecture before planning neuroendovascular or surgical intervention to prevent possible risks.