Subarachnoid blood

Presence of extravasated blood within the subarachnoid space between the arachnoid and pia mater, as visualized on neuroimaging or detected in cerebrospinal fluid.

Causes

• Ruptured intracranial aneurysm

• Arteriovenous malformation (AVM)

• Head trauma

• Coagulopathy and anticoagulant therapy

• Drugs: Cocaine, amphetamine

• Cerebral vasculitis

• Cerebral amyloid angiopathy