Unruptured Intracranial Aneurysms

Over the past 20 years, Wiebers created or helped create numerous guidelines for the medical, surgical and endovascular treatment of patients with unruptured intracranial aneurysms in the United States and internationally (refs # 27, 73, 94, 114, 176, 235, 304, 313, 315, and 320).  He has been involved with a wide range of U.S. and international research projects involving unruptured intracranial aneurysms (UIAs), a disorder that affects approximately 5% of the population at some point in life.  Wiebers, Whisnant and O’Fallon’s study published in the New England Journal of Medicine in 1981 (ref #9) provided the first natural history data regarding UIAs involving long term follow-up of 65 patients. Wiebers, Whisnant, Sundt and O’Fallon published a subsequent report in the Journal of Neurosurgery in 1987 (ref #42) that further developed many of the previous concepts and together the papers rewrote much of the available knowledge about the development, growth, rupture and natural history of UIAs.  Contrary to existing knowledge about unrutured aneurysms, the studies showed that:  1. Larger UIAs have a much greater probability of rupture than small UIAs; 2.  The greater probability of rupture of multi-lobed UIAs relates solely to their increased size; 3.  The size of UIAs is a much greater determinate of future rupture than numerous other variables including patient age, gender, hypertension, number of UIAs, and aneurysmal symptoms other than rupture; and 4.  Intracranial saccular aneurysms are not congenital in nature, but rather develop with increasing age.  Prior to these studies, it had been widely believed within the medical community that large UIAs were less likely to rupture because they had thick walls and that small UIAs were very likely to rupture and therefore essentially all of them needed to be repaired surgically.  

Wiebers and colleagues also provided the first comprehensive assessment of the considerable public health and financial impact of UIAs in the United States population in the journal Stroke in 1992 (ref #110).

From 1991-2007, Wiebers served as Principal Investigator of the International Study of Unruptured Intracranial Aneurysms (ISUIA), a study funded by the U.S. National Institutes of Health involving 61 academic medical centers in 15 countries. Over this period, ISUIA yielded dozens of publications and further changed medical practice regarding UIAs, including aspects related to screening of the population, diagnostic imaging, clinical diagnosis, and indications for treatment by surgical and/or endovascular methods. The study remains the largest of its kind involving unruptured intracranial aneurysms and provides the only prospective comprehensive risk information about treatment and non-treatment options to help patients with UIAs and their doctors decide how best to proceed.  The study led to the medical understanding that patient age, size, location of aneurysm, and history of bleeding from another aneurysm are important decision-making factors in the treatment of UIAs.  This research also led to the realization that unruptured aneurysms are not necessarily “ticking time bombs", as previously believed, some of them have such a low risk of rupture and are better off left untreated (refs # 203, 285, 294, 304, 164, 181, 182, 183, 195, 196, 206, 213, 216, 217, 224, 237, 270, 271, 272, 273, 276, 277, 283, 304, 305, 313, 314, 315, 318, 320, 324, 325, 335, and 344).