[Mechanism of growth of giant intracranial vascular aneurysms. Its demonstration using computer tomography and...

The authors demonstrate three patients with gigantic intracranial aneurysms diagnosed by computed tomography (CT) and angiography (AG). The aneurysm was visualized on the CT as an expansive isodense to slightly hyperdense focus with a sharp hypodense borderline. After administration of the contrast substance the small focus was stained centrally or the slightly excentrically located focus (non-thrombotized portion of the aneurysm); the thrombotized portion of the aneurysm does not change, borders of the aneurysm are more marked (pseudomembrane, highly vascularized fibrous tissue). A number of authors describe findings confirmed on surgery or necropsy where haemorrhage into aneurysmal wall is apparent. Those findings suggest a similar mechanism of growth of the gigantic arterial aneurysm, as assumed in chronic subdural haematomas and encapsulated growing intracranial haematomas. It is assumed that haemorrhage into the aneurysmal wall is covered by a fibrous membrane into which further haemorrhage may occur, the entire cycle is repeated and thus the aneurysm grows. The clinical symptoms are due to the expansive character manifested only when the aneurysm has reached a certain size.