Carotid rete mirabile presenting subarachnoid haemorrhage. Report of two cases

Carotid rete mirabile (CRM) consists of arterial channels between the inter nal and external carotid arteries in some lower mammals. It is a very rare pathological condition in humans. We report two patients who presented with clinical signs of subarachnoid haemorrhage (SAH). Their sudden-onset SAH w as thought to have been due to rupture of cerebral aneurysms, however, angi ograms revealed an abnormal vascular network around the cavernous sinus. To our knowledge, 2 of 7 reported patients with CRM presented with SAH, howev er, only one of these patients had a probable cerebral aneurysm. We suggest that in patients with CRM, the rupture of anastomosing vessels be a probab le cause of SAH.