Causes of spontaneous subarachnoid haemorrhage
| Intracranial aneurysms: degenerative | 60–70% |
| Peri-mesencephalic haemorrhages | 15–20% |
| Arteriovenous malformations and associated aneurysms | 5–10% |
| Other causes: | ∼ 5% |
| Dural fistula | |
| Venous vascular abnormalities | |
| Spinal arteriovenous malformations | |
| Cerebral artery dissections | |
| Moyamoya syndrome | |
| Vasculopathies | |
| Mycotic aneurysms | |
| Coagulopathies | |
| Neoplasia | |
| Pituitary apoplexy | |
| Drug abuse: amphetamine and cocaine |