[Distal aneurysm of posterior inferior cerebellar artery: report of two cases--pitfall in diagnosis].

Two cases treating aneurysms of the distal PICA were reported, and 36 cases with 39 aneurysms in the literatures in Japan were reviewed concerning the distribution of aneurysms and their findings on CT. Case 1; a 68-year-old female suffered from sudden onset of severe headache and nausea. On admission, it was found she was lethargic. However, her consciousness deteriorated down to semicoma with tetraparetic condition soon after. CT revealed subarachnoid hemorrhage in the basal, quadrigeminal and supravermian cisterns and blood clots in the entire ventricle. Cerebral angiography demonstrated an aneurysm located at the distal segment of the left PICA. She was initially treated conservatively because of being in Hunt and Kosnik Grade 5, and then, 3 weeks after onset, suboccipital craniectomy was performed and the aneurysm was clipped successfully. Case 2; a 60-year-old, female, suddenly experienced severe suboccipitalgia and vomiting. CT revealed subarachnoid hemorrhage in the entire subarachnoid space and intraventricular hemorrhages in the 4th, 3rd and lateral ventricles. Subsequently cerebral angiography was performed and left VAG demonstrated an aneurysm at the left A2-A3 junction. She underwent bifrontal craniotomy and the aneurysm was clipped via the interhemispheric approach. Her postoperative course was uneventful. Postoperative left CAG showed successful clipping of the aneurysm. However, left VAG suggested an aneurysm-like shadow in the right PICA. Right BAG carried out one week later demonstrated an aneurysm at the distal segment of the right PICA. This aneurysm was then clipped successfully under suboccipital craniectomy.(ABSTRACT TRUNCATED AT 250 WORDS)