<unk><unk> s may be caused by trauma or may occur spontaneously. Spontaneous SAH is most often due to rupture of cerebral aneurysms (85%), which are weaknesses in the wall of the arteries of the brain that enlarge. 
Beside aneurysmal rupture, other common causes of spontaneous<unk><unk> s include vascular events (such as arteriovenous malformation, dural arteriovenous fistula, perimesencephalic, Intracranial arterial dissection, and amyloid angiopathy), cerebral hyperperfusion syndrome after carotid endarterectomy, brain or cervical tumors, and illicit drug use (such as cocaine andamphetamines).
Subarachnoid hemorrhage causes
Intracranial hemorrhage causes
Intracerebral hemorrhage causes
Subdural hematoma causes
Brain abscess causes
Subdural hematoma risk factors
Cerebral venous sinus thrombosis causes
Aortitis causes