ANEURYSM OF THE POSTERIO INFERIOR CEREBEL LAR ARTERY - ANATOMIC DIAGNOSTIC, THERAPEUTIC AND PROGNOSTIC UPDATE - A MULTICENTER RETROSPECTIVESTUDY OF 29 CASES AND A REVIEW OF THE LITERATURE

A multicenter retrospective study of 29 cases of posterior inferior ce rebellar artery is reported. Over a period of 21 years, the frequency of posterior inferior cerebrellar artery aneurysm among all intracrani al aneurysm was estimated to 1.38 p. 100 of cases of aneurysms followe d by 3 University Hospitals. Frequency of rupture appeared to be very high (93 p. 100) in this series probably because of the type of select ion. Average grade of presentation according to Hunt and Hess classifi cation being < III in 3 fourth of the cases. Neither clinical presenta tion nor suspicious etiological factors were specific of this localiza tion. Only two cases were of pseudotumoral appearance. Positive diagno sis of subarachnoid hemorrhage was mao by CT scan. Angiograms gave dia gnosis of localization of the malformation and its type. Intraventricu lar hemorrhage was found in 62 p. 100 of our cases: all had hemorrhage of the fourth ventricle. Hydrocephaly was more frequent as compared t o supratentorial localizations, Vasospasm was less frequent as in supr atentorial localizations. Nimodipin seems to be efficient. Therapeutic possibilities are primary dominated by surgery with good results when it is possible. Endovascular treatment is under evaluation.