5B. Subarachnoid haemorrhage (SAH)

Page created on June 3, 2021. Last updated on April 6, 2022 at 10:11

Definition and epidemiology

Subarachnoid haemorrhage (SAH) can be traumatic or nontraumatic. This topic will cover the nontraumatic, topic 19 will cover the traumatic. Traumatic SAH is more common than nontraumatic.

Nontraumatic SAH is one form of haemorrhagic stroke. The prognosis is very poor. Up to 40% don’t reach the hospital at all. The 30-day mortality rate is ~50%, and many of those who survive sustain severe disability and decrease in quality of life.


  • Rupture of intracranial aneurysm in the circle of Willis
    • Risk factors for developing aneurysm: smoking, female, hypertension, alcoholism, family history
    • Risk factors for rupturing aneurysm: acute hypertension, strain
  • Rupture of arteriovenous malformation or angiomas

Aneurysmal SAH accounts for 70% of nontraumatic SAH. Non-aneurysmal SAH is more common in younger patients.

Clinical features

SAH causes a characteristic headache called “thunderclap headache”, which occurs hyperacutely and is usually described by patients as “the worst headache of their lives”. Other symptoms include loss of consciousness, seizures, and focal neurological symptoms. Meningism (stiff neck, photophobia, vomiting), can occur due to blood in the CSF. Patients also usually have severe hypertension.

20% of patients have warning symptoms in the days before the SAH. These warning symptoms are usually transient and can be diplopia or headache.

Diagnosis and evaluation

SAH is a form of stroke and so is evaluated as one with native CT urgently. It will show hyperdense blood in the subarachnoid space. If the CT is negative but the suspicion for SAH is still high, we can perform MRI or a lumbar puncture. LP will show yellowish/reddish CSF with RBCs, called xanthochromia.

Vascular imaging, by DSA or CT angiography, should be performed afterward to identify the source of the bleeding, in order to plan the treatment. Transcranial doppler can be used to look for vasospasm.


As a stroke, the patient should be admitted to a stroke unit. Unfortunately, there are fewer treatment options for haemorrhagic stroke than for ischaemic stroke. The goal of the management is to treat and prevent the complications of SAH, especially rebleeding.

If vascular imaging shows bleeding from an aneurysm, neurosurgery can perform endovascular coiling or clipping of the aneurysm to stop bleeding and prevent rebleeding. If there is vasospasm we can use nimodipine to decrease it.

If the patient is on anticoagulation, they should be stopped and reversed by the appropriate measures (FFP or specific reversal agents). Supportive care is important. The BP should be lowered to 140 mmHg.


  • Rebleeding (common)
  • Vasospasm leading to ischaemia
  • Hydrocephalus
  • Epilepsy
  • Hypopituitarism (can occur long time after)

Previous page:
5A. Polyneuropathies

Next page:
6A. Neuroimaging

Parent page:
Neurology 2

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