[The prognostic value of computerized tomography in acute aneurysmal subarachnoid haemorrhages]

The radiological diagnosis of subarachnoid haemorrhages (SAH) is based fundamentally on studies using computerised tomography, although magnetic resonance imaging has also been proved to be highly sensitive. Spontaneous SAH is essentially due to the rupture of a cerebral aneurysm. The distribution of the SAH and the presence of associated haemorrhagic lesions are useful for developing a suspicion as to the exact whereabouts of the aneurysm causing the SAH.

SAH is still linked to a poor prognosis despite the progress made in its diagnosis and treatment. Several radiological factors have been reported as being associated to a poorer prognosis: 1. The risk of complications is related to the extension of the SAH. The most widely accepted classification for determining the extension is the one put forward by Fisher. The higher grades III and IV are linked to a higher rate of morbidity and mortality. 2. SAH that is situated in the perimesencephalic cisterns is linked to a low risk of being of aneurysmal origin and to a good progression. 3. A size above 10 mm is linked to a poorer progression. 4. Finally, the appearance of any of the possible complications (vasospasm, rebleeding, haemorrhage, edema) is also linked to a poorer prognosis.