[Three cases of giant aneurysm of the distal posterior inferior cerebellar artery].

Posterior inferior cerebellar artery (PICA) aneurysms constitute approximately 3-6% of all intracranial aneurysms. Especially, aneurysms which originate from distal portion of PICA are very rare. We experienced 4 cases of distal PICA aneurysm, 3 cases of which were giant sized. The clinical and radiological features of cases of a giant aneurysm of distal PICA are analyzed in this study. They consisted of 2 male and 1 female, ranging in age from 37 to 66. They had suffered from headache, disturbances of cranial nerves, cerebellar disorders and dementia, caused by subarachnoid hemorrhage and mass effects of aneurysms. Aneurysmal cavity without organization was shown as a large hyperdensity area in enhanced CT scans, but organized cavity was not enhanced. Angiograms showed that two giant aneurysms in our cases originated from the cranial loop of PICA. Vascular abnormalities such as the vertebral artery terminating as PICA in one case and multiple aneurysms in another case were also seen. As for the treatment, in two cases proximal ligation resulting no neurological deficit was performed. In another case, because of complete organization of the aneurysmal cavity and adhesion between the aneurysm and the brain stem, extirpation of the aneurysm could not be done. In one patient who had symptomes of cerebellar disturbance, removal of the thrombus resulted in good recovery.