it may occur spontaneously, usually from a ruptured cerebral aneurysm (focal outpouchings with weakened walls on the arteries on the brain surface that are prone to rupture). Symptoms of SAH include a severe headache with a rapid onset (thunderclap headache), vomiting, confusion or a lowered level of consciousness, and sometimes seizures. CT scan has 100% sensitivity of detecting SAH at 6 to 24 hours after symptoms onset. The diagnosis is generally confirmed with a CT scan of the head. If CT scan is normal but SAH is still strongly suspected, lumbar puncture can be done at six to twelfth hours after the onset of headache. This is determine the presence of blood within the cerebrospinal fluid (CSF). Those with SAH will have blood and bilirubin within CSF because of degradation red blood cells. Meanwhile, those who has blood within CSF due to traumatic lumbar puncture will not have bilirubin within CSF. SAH is generally located within basal cisterns, extends diffusely to all subarachnoid spaces (cerebral sulci) or into the ventricular system, or brain parenchyma. Modified Fisher scale is used to describe the volume and distribution of SAH, just predicting the probability of cerebral artery vasospasm after SAH. Treatment is by prompt neurosurgery or radiologically guided interventions with medications and other treatments to help prevent recurrence of the bleeding and complications. Since the 1990s, many aneurysms are treated by a minimal invasive procedure known as endovascular coiling, which is carried out by instrumentation through large blood vessels. However, this procedure has higher recurrence rates than the more invasive craniotomy with clipping. Cerebral ateriovenous malformation Cerebral ateriovenous malformation (Cerebral AVM) is characterised by abnormal shunting between cerebral arteries and veins without going through capillaries. Instead the blood goes through a collection of small vessels from arteries to veins. These collection of abnormal small vessels is termed as "nidus". This condition happens in 0.1% of the population has a risk of 2 to 4% per year for intracranial bleeding. Once ruptured, it results in intraparenchymal hemorrhage, intraventricular hemorrhage and SAH. Rupture of cerebral AVM often occurs in young people and children. Cerebral AVM can be diagnosed by computed tomography angiography (CTA) brain, magnetic resonance angiography (MRA) brain, or digital subtraction angiography (DSA). DSA is important to determine whether there is nidal or perinidal aneurysm. Dural arteriovenous fistulae Dural arteriovenous fistulae (DAVF) is the direct connection between dural or cerebral arteries with dural venous