A subarachnoid haemorrhage (SAH) is a type of stroke that causes bleeding around the brain. Subarachnoid haemorrhage, the bleeding happens in a part of your head called the “subarachnoid space.” Most spontaneous SAHs are caused by ruptured saccular aneurysms. Other causes of SAH include occult trauma, arteriovenous malformations/fistulae, vasculitides, intracranial arterial dissections, amyloid angiopathy, bleeding diatheses, and illicit drug use (especially cocaine and amphetamines).