- An aneurysm is an abnormal local dilatation in the wall of a blood vessel, usually an artery, due to a defect, disease or injury
- Morphological forms include:
Saccular
(Berry)
(Berry)
- The most common form
- Mainly occurs at the bifurcation of intracranial arteries
- Results from local medial degenerations following haemodynamic-induced stress on the wall between the two exiting branches
- Size varies from a few millimetres to several centimetres - those >2.5 cm are termed ‘giant’ aneurysms
Fusiform
- Most commonly seen in the carotid and basilar artery
- Found in older patients
- Caused by unusual and excessive atherosclerotic breakdown of the intima
- Rarely lead to rupture
Mycotic
- Weakening of the vessel wall due to infection
- Occur secondary to haematogenous spread (e.g. bacterial endocarditis)
Dissecting
- Accumulation of blood within the wall of the vessel between the intima and the elastic lamina
- Can arise spontaneously or following trauma
- Also found in underlying vasculopathy, usually within the vertebral artery