Subarachnoid Haemorrhage (SAH)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Example Management | References

Definition

Subarachnoid Haemorrhage (SAH) is a type of stroke caused by bleeding into the subarachnoid space, the area between the arachnoid membrane and the pia mater surrounding the brain. This condition is a medical emergency that requires immediate attention.

Aetiology

Subarachnoid Haemorrhage can result from various causes, including:

• Aneurysmal SAH: Rupture of a cerebral aneurysm (the most common cause).
• Non-aneurysmal perimesencephalic SAH: Bleeding around the midbrain not associated with an aneurysm.
• Traumatic SAH: Resulting from head injury.
• Other causes: Arteriovenous malformations (AVMs), vasculitis, bleeding disorders, and illicit drug use (e.g., cocaine).

Pathophysiology

In SAH, bleeding occurs in the subarachnoid space, leading to increased intracranial pressure, irritation of the meninges, and impaired cerebrospinal fluid circulation. The blood can also cause vasospasm, leading to reduced blood flow to the brain and potential ischaemic injury. Secondary complications include hydrocephalus and rebleeding.

Risk Factors

• Age: Incidence increases with age.
• Gender: More common in females.
• Hypertension: Increased blood pressure can weaken blood vessel walls.
• Smoking: Contributes to the formation and rupture of aneurysms.
• Family history: Genetic predisposition to aneurysms or bleeding disorders.
• Alcohol and drug use: Particularly cocaine and heavy alcohol consumption.

Signs and Symptoms

• Sudden, severe headache (often described as a "thunderclap" headache).
• Nausea and vomiting.
• Neck stiffness and photophobia (sensitivity to light).
• Altered mental status or loss of consciousness.
• Focal neurological deficits (e.g., weakness, speech difficulties).
• Seizures.

Investigations

• Clinical history and physical examination, including neurological assessment.
• Non-contrast CT scan of the head: The initial imaging study to detect acute bleeding.
• Lumbar puncture: If the CT scan is negative but SAH is still suspected (look for xanthochromia).
• Cerebral angiography (CTA or MRA): To identify the source of bleeding, such as an aneurysm or AVM.
• Electrocardiogram (ECG) and blood tests to assess overall health and identify contributing factors.

Management

Primary Care Management

• Immediate assessment and stabilisation of the patient, ensuring airway, breathing, and circulation (ABCs).
• Urgent referral to a specialist (neurologist or neurosurgeon) or transfer to a hospital with neurosurgical capabilities.
• Initial pain management and supportive care while awaiting specialist assessment.

Specialist Management

• Surgical intervention: Clipping of the aneurysm or endovascular coiling to prevent rebleeding.
• Medical management: Control of blood pressure, prevention of vasospasm (e.g., with nimodipine), and management of complications such as hydrocephalus.
• Intensive monitoring: Neurological and cardiovascular monitoring in an intensive care unit (ICU).
• Rehabilitation: Physiotherapy, occupational therapy, and speech therapy to address long-term deficits.
• Regular follow-up: Monitoring for complications and assessing recovery.

Example Management for Subarachnoid Haemorrhage

A patient presenting with a sudden, severe headache and neck stiffness should be urgently referred to a hospital for immediate imaging, such as a non-contrast CT scan. If SAH is confirmed, the patient may undergo cerebral angiography to identify the source of bleeding. Surgical intervention, such as clipping or coiling of the aneurysm, may be performed to prevent rebleeding. The patient should be managed in an ICU with intensive monitoring and supportive care. Rehabilitation services may be necessary to address any long-term deficits, and regular follow-up is essential to monitor recovery and manage complications.

References

1. NICE. (2024). Subarachnoid Haemorrhage: Diagnosis and Initial Management. Retrieved from NICE
2. NHS. (2023). Subarachnoid Haemorrhage. Retrieved from NHS
3. Connolly, E. S., et al. (2012). Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage. Stroke.
4. Steiner, T., et al. (2013). European Stroke Organization Guidelines for the Management of Intracranial Aneurysms and Subarachnoid Haemorrhage. Cerebrovascular Diseases.
5. van Gijn, J., et al. (2007). Subarachnoid Haemorrhage. The Lancet.

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