Pattern of reticular fibres of the major cerebral arteries in cases of unexplained subarachnoid haemorrhage.

The pattern of reticular fibres was studied in the intracranial arteries of six patients who did of subarachnoid haemorrhage without demonstrable cause. In each patient, the media of all of the major intracranial arteries contained much fewer reticular fibres than those of individuals without vascular disease. These fibres were mainly sparser in the outer part of the media, resembling the pattern seen in patients with ruptured berry aneurysms. It is concluded that the deficiency in reticular fibres may predispose to rupture even at the early stage of aneurysm formation.