A thunderclap headache is an uncommon presentation of headache but is important to recognise because it is often associated with serious vascular intracranial disorders, and should therefore be investigated urgently. Aneurysmal subarachnoid haemorrhage is the foremost consideration, and reversible cerebral vasoconstriction the next most common cause. The causes and diagnostic approach to patients with thunderclap headache are discussed.
- The cause of thunderclap headache should be considered to be aneurysmal subarachnoid haemorrhage until proven otherwise.
- The diagnostic work up involves urgent nonenhanced CT of the brain (with CT angiography if immediately available), then possibly a lumbar puncture, and then cerebral arterial and venous imaging with either MRI or CT if each preceding investigation has yielded a normal/negative result.
- Reversible cerebral vasoconstriction syndrome is usually characterised by recurrent thunderclap headaches and multifocal, multivessel segmental cerebral artery vasoconstriction that usually resolve within 12 weeks. It can be associated with neurological complications including intracerebral haemorrhage and cerebral ischaemic infarctions.
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