Definition

It is the bleed in Subarachnoid space(The space between arachnoid and pia matter)

Risk factors

• Intracranial aneurysms
• Trauma
• Vascular malformations (arteriovenous malformations)
• Moyamoya syndrome
• Coagulopathy
• Extension of intracerebral hematoma.
• Hypertension
• Polycystic kidneys
• Coarctation of aorta

Clinical Features

• Severe headache
• Nausea, vomiting
• Syncope
• Third and sixth cranial nerve palsies
• Seizures
• Lethargy
• Meningism
• Photophobia
• Neck stiffness

Preceding symptoms

• Headache
• Diplopia especially during exertion

Investigations

• Bloods- FBC, Renal functions, Blood sugars
• CT scan
• ECG
• Chest X-ray
• Lumbar puncture if CT normal and no focal neurological signs and no papilledema

Grading 

Fisher Scale for Grading SAH on Admission CT Scan

Grade        CT Finding

Grade 1       No blood visualized

Grade 2       Layer of blood (over interhemispheric fissure, insular cistern, ambient cistern) less than 1 mm thick 

Grade 3       Localized clots or layer of blood 1 mm or greater in thickness 

Grade 4       Diffuse or no subarachnoid blood, but with intracerebral or intraventricular clots