Advances in diagnosis and treatment of intracranial aneurysms

The term aneurysm usually refers to a persistent pathologic dilatation of an arterial wall. Arterial aneurysms can be classified according to shape, size, site and etiology. The shape can be described as fusiform, when the whole vessel circumference is involved, or saccular when the lesion is eccentric. They can also be described according to etiology, it is accepted that genetic and environmental risk factors play a role in the pathogenesis of intracranial aneurysms. Fusiform aneurysms and dolichoectasia (elongation, widening and tortuosity of a blood vessel) most commonly involve the basilar artery and are typically related to advanced atherosclerosis. Other rare types of aneurysms are: mycotic (infective) aneurysms (they account for approximately 2.5-4.5% of intracranial aneurysms); traumatic; and dissecting aneurysms. Unruptured intracranial aneurysms (UIAs) are prevalent in 3% of the adult population. The overall incidence of subarachnoid haemorrhage is approximately 9 per 100000 person-years. Rates are higher in Japan and Finland and increase with age. Once developed, intracranial aneurysms may remain stable for long time, may grow slowly, or may rupture leading to subarachnoid haemorrhage, a medical emergency. The aim of this thesis was to increase our insight into diagnosis and treatment of intracranial aneurysms.