Background: Persistent fetal carotid-vertebrobasilar anastomoses are rare, with an incidence of <1%. The most common anomaly seen in this group is a persistent primitive trigeminal artery; others such as a persistent hypoglossal artery account for less than 15% of all persistent fetal anastomoses, making this finding exceedingly rare. Methods: We present the case of a 32-year-old-female with Poland syndrome (right-sided), who presented with thunderclap headache and reduced level of consciousness secondary to diffuse subarachnoid hemorrhage and hydrocephalus. CT and catheter angiography demonstrated an aneurysm of the V4 segment of the right vertebral artery arising from a persistent right hypoglossal artery, with an absent ipsilateral vertebral artery proximal to the anomaly. Results: Hydrocephalus was treated with an EVD, followed by a successful embolization of the V4 aneurysm with Axium coils. Subsequent MR studies demonstrated minimal recanalization of the aneurysm, and small foci of possible infarcts in the hippocampi. Four months later, the patient has some persistent short term memory difficulties but is otherwise neurologically intact. Conclusions: We present a rare finding of a persistent fetal hypoglossal artery with an associated vertebral aneurysm. The aneurysm was successfully treated endovascularly through coil embolization with minimal residual -neurological deficit. This vascular anomaly was ipsilateral to her Poland Syndrome defects.