Peripheral aneurysms of the posterior inferior cerebellar artery.

Nonmycotic peripheral posterior inferior cerebellar artery (PICA) aneurysms are rare. The authors report six cases of peripheral PICA aneurysm. Two of these are unusual; one was fusiform and another was a double aneurysm arising from the peripheral PICA. The previously reported 40 cases of peripheral PICA aneurysm are reviewed.