thunderclap headache

Last reviewed 06/2023

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)
    • 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 hemorrhage (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 (2)

Thunder clap headaches can be

  • primary
    • diagnosed when no underlying cause is discovered (3)
    • ICHD-II classification states that normal brain imaging and CSF are required before a diagnosis (1)
    • 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).

Notes (1):

  • 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:

 

Related pages:

secondary causes of thunderclap headache

clinical presentation

investigations

reversible cerebral vasoconstriction syndrome (RCVS)