A non-haemorrhagic "thunderclap" headache (TCH) is a diagnosis of exclusion made in patients whom present with severe headache but have a negative CT and LP.
- differential diagnosis with the sentinel headache observed during the development of an aneurysmal rupture is extremely important (1,2)
- all patients with TCH should be investigated with at least a CT scan and MR angiography, since this type of headache is not a frequent benign recurrent headache disorder, and may represent a serious underlying process
TCH is defined by the ICHD-II as a severe intense headache which is of rapid onset mimicking a subarachnoid haemorrhage (SAH) from a ruptured aneurysm with maximum intensity being reached in less than a minute (1)
- the incidence in the developed world is estimated to be around 43 per 100,000 adults per year
Thunder clap headaches can be
- primary
- diagnosed when no underlying cause is discovered
- ICHD-II classification states that normal brain imaging and CSF are required before a diagnosis (1,2)
- although introduced in the second version of the International Classification of Headache Disorders as a different entity, there are doubts about whether primary thunderclap headaches really exists
- secondary
Patients with a first presentation of thunderclap headache should be referred immediately to hospital for same day specialist assessment (1,2).
Notes (1,2):
- the pathophysiology of TCH in the absence of underlying pathology is not well understood
- primary TCH has a distinctive clinical and angiographic profile and must be distinguished from central nervous system vasculitis and SAH
Reference:
- SIGN (March 2008).Diagnosis and Management of headaches in adult.
- NICE. Headaches in over 12s: diagnosis and management. Clinical guideline CG150. Published September 2012, last updated December 2021