A long time follow-up study of a single-institution series can provide reliable information on surgical results of cerebral aneurysms. Therefore, of 840 patients with cerebral aneurysms operated at Niigata Rohsai Hospital, 482 cases were studied to determine the incidence of recurrent subarachnoid hemorrhage (SAH). Seven patients (5 from de novo, and 2 from growth of residuum) developed recurrent SAH at a mean interval of 87.0 months, yielding an overall hemorrhage risk of 0.20% and a hemorrhage risk from originally clipped site of 0.0042% per year. To reveal de novo aneurysms formation and the fate of clipped aneurysms, 128 cases underwent late follow-up angiography and/or 3-dimensional computed tomography (3DCT). Eight de novo aneurysms were found at a mean interval of 96.4 month postsurgery for a annual risk of 0.78% per year. Eight residua were noted, of which 5 enlarged.
We conclude 1) long-term efficacy of aneurysm clipping showed a very high permanent obliteration rate, 2) the patients with aneurysms have a high risk of recurrent SAH, even after a “satisfactory” clipping of the aneurysms, at about 10 times that of the general population. Based on these findings and a review of the reported literature, we suggest the following for optimal late review: 1) 3DCT and/or MRA review is probably required to discover de novo as screening for routine, 2) the necessity of late angiographic study should be weighted with a known residua, 3) closer surveillance of females with multiple aneurysms is warranted more than in males.
