Update on subarachnoid haemorrhage.

Subarachnoid haemorrhage (SAH) is less frequent than ischaemic stroke or intracerebral haemorrhage, but has a high public health relevance because it can affect young and middle-age adults, has considerable mortality and morbidity, it is treatable and preventable. SAH is traditionally a topic for neurosurgeons. However as endovascular interventions are becoming effective alternatives to surgical treatment, SAH should turn out to be of interest to neurologists, in particular to those devoted to stroke, emergency and neurointensive care. Despite stable incidence, the mortality of SAH has decreased in the last two decades due to better neurosurgical techniques and neurocritical care and to advances in interventional neuroradiological procedures. We review the recent advances in the clinical and diagnostic aspects of SAH and in the genetics of intracranial aneurysms. A systematic review of the treatment of SAH and grading of the available evidence is included.