A thunderclap headache is defined as a very severe headache that reaches its maximum intensity within 1 minute.
One of the most common causes (and the one associated with this buzzword on board questions!) is subarachnoid hemorrhage, but what else can cause a it?
- Reversible cerebral vasoconstriction syndrome (RCVS): suggested by recurrent thunderclap headaches (2-10) over 1 to 2 weeks. Normal CT and LP, with vasoconstriction on angiography. Can lead to SAH, ICH or ischemic stroke.
- Cervical artery dissection
- Cerebral venous sinus thrombosis
- Spontaneous intracranial hypotension: characterized by orthostatic HAs and auditory muffling.
- Intracerebral hemorrhage
- “Primary”: a diagnosis of exclusion
Bottom line? All patients with thunderclap HA should have a stat head CT with no contrast, then have SAH excluded with an LP, CTA or MRI/MRA. Just because you excluded SAH in a patient with thunderclap headache does not mean you’re done with the emergency workup.
