Ruptured aneurysm at the choroidal branch of the posterior inferior cerebellar artery: a case report, review of the literature and proposed pathogenesis.

Aneurysms rarely occur at the choroidal branch of the posterior inferior cerebellar artery (PICA) and their pathogenesis is not well understood. We report such a case and review the literature. A 69-year-old female was admitted for a sudden onset of severe headache with nausea and vomiting. Soon after arrival, she became less responsive. CT of the head revealed an intraventricular haemorrhage (IVH) predominantly in the fourth and third ventricles without subarachnoid hemorrhage and associated with hydrocephalus. Cerebral angiography demonstrated an aneurysm at the choroidal branch of the PICA. The aneurysm was resected through a bilateral suboccipital craniotomy. The patient made a remarkable recovery. The literature describes five other cases of aneurysms arising from a choroidal branch of the PICA. Hypertension was a common finding in this population. In summary, aneurysms arising from a choroidal branch of the PICA are rare. Hypertensive vessel damage might be a major factor in their pathogenesis. We propose that the rupture of a hypertensive aneurysm might account for some isolated spontaneous IVH.