[Incidental aneurysms and perimesencephalic subarachnoid haemorrhages]. / Aneurismas incidentales en el contexto de hemorragias subaracnoideas perimesencefálicas.

A perimesencephalic subarachnoid hemorrhage refers to the presence of bleeding around the midbrain with a normal angiography, meeting the well established clinical criteria and radiological criteria. Unlike the aneurysmal subarachnoid hemorrhage, it has a good prognosis, the recovery in most cases being complete and satisfactory. On the other hand, between 2 and 5% of the population will develop an intracranial aneurysm in the course of their life, most of them asymptomatic, with the likelihood of finding an incidental aneurysm in patients who have suffered a perimesencephalic hemorrhage. The importance of a proper diagnosis governs the course to follow, being a challenge for vascular treatment teams who must analyse the findings in detail and individualize treatment decisions.