Carotid Rete Mirabile Presenting Subarachnoid Haemorrhage. Report of Two Cases

¶ Carotid rete mirabile (CRM) consists of arterial channels between the internal 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 was thought to have been due to rupture of cerebral aneurysms, however, angiograms revealed an abnormal vascular network around the cavernous sinus. To our knowledge, 2 of 7 reported patients with CRM presented with SAH, however, only one of these patients had a probable cerebral aneurysm. We suggest that in patients with CRM, the rupture of anastomosing vessels be a probable cause of SAH.