Clinical features of subarachnoid hemorrhages

1. Big picture

Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space, most commonly caused by rupture of a saccular intracranial aneurysm around the circle of Willis.

For the exam, SAH is the classic cause of:

Sudden, extremely severe thunderclap headache + nuchal rigidity ± vomiting ± photophobia ± loss of consciousness.

The key clinical warning is:

A patient who says “this is the worst headache of my life,” especially during exertion, lifting, straining, or sexual intercourse, has subarachnoid hemorrhage until proven otherwise.

SAH is life-threatening because the patient may die from:

• Initial bleeding

• Rebleeding

• Vasospasm and delayed cerebral ischemia

• Hydrocephalus

• Raised intracranial pressure

• Herniation

• Arrhythmias and neurogenic pulmonary edema

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