Vikas Pandey, MD
Fusiform intracranial aneurysms are an entity that are not well studied, mainly due to the fact that fusiform aneursysms are rarer compared to saccular ones. The concept that the etiology of fusiform aneurysms is multifold leads to questions whether the approach to treat these types of aneuryms should be different based on specific aneurysmal characteristics as well as parts of the patient’s medical history. The authors headed by the interventional neuroradiology group from Toronto challenged the idea that treating fusiform intradural aneurysms carries a poor prognosis, an idea that has been ingrained due to poor prognosis of previously studied populations of veretebrobasilar fusiform aneurysms, and proposed that the natural histories of the different etiologies of fusiform aneurysms may be different.
The author conducted a retrospective study of patients seen between a 13 year period at Toronto Western Hospital cerebrovascular clinic and looked at 121 patients with unruptured intradural aneurysmal dilatation of >50% of the vessel wall circumference. Patients that were excluded were those with diameter >2.5 cm (these have a known poor natural history) and those with entirely extradural aneurysms. The aneurysms were categorized into those that were related to atherosclerosis and those that weren’t based on imaging criteria such as presence of eccentric, calcified plaques present within the aneurysms, as well as with supporting criteria based on risk factors for atherosclerosis (25 out of 121 put into this group). The groups were followed for 193 and 97 person-years for the non-atherosclerotic and atherosclerotic groups respectively. Results showed that the mortality in the atherosclerotic group was higher (5.2%/year vs 0.51%/year) and they had a higher aneurysm progression risk (12%/year vs 1.6%/year compared to the non-atherosclerotic counterparts.
The results provide an interesting dimension to treatment algorithms for fusiform aneurysms. The common sense risk factors such as a size and symptomatic presentation are not to be overshadowed, but looking into aspects of the pathophysiology of aneurysms which may appear similar on initial radiographic studies is an idea that should be applied to all areas of medicine. The authors bring up the very valid point that atherosclerotic aneurysms and non-atherosclerotic fusiform aneurysms should be thought of as entirely different disease entities. “Cookie cutter” medicine is very hard, especially in the field of stroke neurology and the authors provide us with an excellent example of this.