Posterior inferior cerebellar artery origin thrombosis with aneurysm of collateralized posterior meningeal artery presenting as subarachnoid hemorrhage: case report.

OBJECTIVE

This is the first report of a ruptured aneurysm involving a collateral branch to the posterior inferior cerebellar artery (PICA) in a patient who had a subarachnoid hemorrhage.

CLINICAL PRESENTATION: A 56-year-old man initially presented with a subarachnoid hemorrhage and underwent 2 catheter-based 4-vessel angiograms with negative results. A delayed angiogram 4 weeks later revealed a dissecting aneurysm of the posterior meningeal artery, a branch of the vertebral artery.

INTERVENTION: A 3-dimensional reconstruction of the vertebral angiogram showed proximal occlusion of the proximal left PICA and distal filling via a collateral branch from the posterior meningeal artery. A far-lateral approach was used for this patient. The aneurysm was found along the course of the collateral posterior meningeal artery and was clipped successfully.

CONCLUSION

Aneurysms involving collateral branches of the PICA are rare. It is important to recognize such collateral flow preoperatively because inadvertent sacrifice of these vessels during a surgical approach could lead to stroke and neurological deficits of the PICA territory.