Persistent primitive hypoglossal artery presenting with perimesencephalic nonaneurysmal subarachnoid hemorrhage: A case report and review of literature

Background Persistent primitive hypoglossal artery (PPHA) is a rare remnant of the congenital carotid-basilar artery anastomosis, sometimes associated with subarachnoid hemorrhage (SAH), and aneurysms are the more common cause. However, the association of PPHA with perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH) is extremely rare. This report is the first to describe the occurrence of PNSAH concerning PPHA. Case description A 53-year-old man suffered from subarachnoid hemorrhage with a sudden severe headache. An emergency brain computed tomography (CT) disclosed a perimesencephalic pattern of SAH. CT angiography (CTA) revealed a right PPHA entering the posterior fossa through the right enlarged hypoglossal canal. No source of the hemorrhage was identified in the imaging examinations, even with the performance of a 4-vessel angiography. Conclusion We present a case of PPHA associated with PNSAH and review the literature. The main cause for the PPHA related to SAH is an aneurysm. The four vessels angiography helped rule out an aneurysm that is associated with a poorer prognosis and requires immediate active management. It is, therefore, essential for physicians to be aware of the increased incidence of aneurysms in PPHA to make the correct diagnosis.