🚨 Subarachnoid Haemorrhage
Overview
Subarachnoid haemorrhage (SAH) is bleeding into the subarachnoid space, typically caused by rupture of an intracranial aneurysm. It presents as a sudden, severe headache and is a life-threatening emergency with high mortality and morbidity.
Recognition
Sudden onset 'thunderclap' headache (worst headache of life), often associated with neck stiffness, photophobia, nausea/vomiting, and altered consciousness. May have focal neurological deficits or seizures. Sentinel headache (warning leak) may precede major bleed.
Initial Assessment (ABCDE)
ABCDE approach is paramount. Secure airway, ensure adequate oxygenation and ventilation. Assess neurological status using GCS and look for focal deficits. Control blood pressure to prevent re-bleeding, but avoid hypotension. Look for signs of meningism.
Red Flags
Decreasing GCS, new focal neurological deficits, pupillary changes, seizures, signs of raised ICP. These indicate re-bleeding, hydrocephalus, or vasospasm, all requiring urgent intervention.
Investigations
Bedside: GCS, pupil assessment, vital signs, ECG. Bloods: FBC, U&Es, coagulation screen, group and save. Imaging: Urgent non-contrast CT head is the initial investigation. If CT is negative but suspicion remains high, lumbar puncture for xanthochromia is required. CT angiography to identify aneurysm.
Immediate Management
Maintain normotension (avoid extremes). Administer analgesia for headache and antiemetics for nausea. Consider nimodipine to prevent vasospasm. Elevate head of bed to 30 degrees. Treat hydrocephalus if present (e.g., external ventricular drain). Prepare for neurosurgical or interventional neuroradiological management.
Escalation Triggers
Any suspected SAH requires immediate emergency department attendance and urgent neurosurgical consultation. Patients with confirmed SAH, neurological deterioration, or signs of hydrocephalus need critical care involvement and urgent definitive treatment of the aneurysm.
MLA High-Yield Notes
The 'thunderclap' headache is the classic symptom. CT head is highly sensitive within 6 hours of symptom onset. Xanthochromia on LP confirms SAH if CT is negative. Vasospasm is a major complication, prevented by nimodipine. Aneurysm clipping or coiling are definitive treatments.
References
- NICE Guideline CG162: Stroke and TIA: diagnosis and initial management
- Resuscitation Council UK: Advanced Life Support (ALS) guidelines
- RCEM Learning: Subarachnoid Haemorrhage