Subarachnoid hemorrhage

Learning objectives

Etiology
- Intracranial aneurysm (85% of cases)
- Arteriovenous malformations
- Trauma
- Moyamoya disease
Risk factors
- Hypertension
- Atherosclerosis
- Cocaine use
- Alcohol abuse
- Smoking
- Connective tissue disorders
- Coarctation of the aorta
- Congenital conditions (autosomal-dominant polycystic kidney disease, Ehlers Danlos Type 4, familial intracerebral aneurysms)
Cause
- Hemodynamically induced shear stress (sudden increase in cerebrovascular arterial pressure)
Aneurysmal rupture leads to blood quickly traversing through the intracranial cisterns and subarachnoid space (within seconds)
Global cerebral ischemia resulting from increased intracranial pressure, decreased cerebral perfusion, and reduced cerebral blood flow
Intraventricular bleeding can cause acute ventricular dilatation and hydrocephalus
Brain tissue oxygen pressure and pH are reduced
Compensatory hypertension occurs within minutes to hours
Blood-brain barrier disruption, cerebral edema, and a thromboinflammatory cascade

Non-contrast cranial CT
Lumbar puncture in patients with a high index of suspicion and a normal CT scan (red blood cell count, bilirubin level, and xanthochromia)
CT angiogram and/or digital subtraction angiography to identify the cause

Grade	World Federation of Neurologic Surgeons	Hess and Hunt	Fisher (CT scan appearance)
1	Glasgow Coma Scale score 15, no motor deficit	Asymptomatic or minimal headache and slight nuchal rigidity	No blood detected
2	Glasgow Coma Scale score 13-14, no motor deficit	Moderate to severe headache nuchal rigidity, no neurological deficit other than cranial nerve palsy	Diffuse thin layer of subarachnoid blood (vertical layers <1 mm thick)
3	Glasgow Coma Scale score 13-14 with motor deficit	Drowsy, confusion, or mild neurological deficit	Localized clot or thick layer of subarachnoid blood (vertical layers ≥1 mm thick)
4	Glasgow Coma Scale score 7-12, with or without motor deficit	Stupor, moderate-to-severe hemiparesis, possibly early decerebrate rigidity and vegetative disturbances	Intracerebral or intraventricular blood with diffuse or no subarachnoid blood
5	Glasgow Coma Scale score 3-6, with or withour motor deficit	Deep coma, decerebrate rigidity, moribund appearance

- Endovascular coiling: Preferred in geriatric patients, particularly those with high-grade aneurysmal subarachnoid hemorrhage from the rupture of basilar apex aneurysm
- Surgical clipping: Preferred in patients with large intraparenchymal hematomas, aneurysm of the middle cerebral artery, and in those not likely to be compliant with long-term follow-up