Background
- "Thunderclap headache" is a severe headache that peaks (pain >7/10) within 60 seconds of onset
- Subarachnoid haemorrhage (SAH) is the most common cause
Any thunderclap headache, even in a patient with a history of recurrent headache, such as migraine, must be considered as secondary to a variety of causes e.g. subarachnoid haemorrhage.
Other causes include:
- ↑ICP
- Infection
- ↑BP syndrome
- Cervical artery dissection
- Cerebral venous thrombosis
- RCVS
Differential Dx clues
Neck stiffness:
- SAH or meningitis
Transient loss of consciousness:
- SAH (around 50% of cases)
- Colloid cyst of 3rd ventricle
Epileptic seizure:
- SAH, other stroke
- Cerebral venous thrombosis
Focal neurological symptoms:
- Subarachnoid haemorrhage; other stroke
- Cerebral venous thrombosis
- RCVS
Mild trauma:
- Cervical arterial dissection, intracranial hypotension
Intake of vasoactive substances:
- Illicit (cannabis, cocaine, ecstasy, amphetamines, LSD)
- Antidepressants (e.g. SSRIs)
- Sympathomimetics (nasal decongestants, norepinephrine)
- Migraine drugs (triptans and ergot alkaloid derivatives)
RCVS
Dural puncture:
Fever:
- Infectious disorders
Post-partum:
ENT symptoms:
- Complicated sinusitis
Horner’s sign, pulsatile tinnitus or tongue palsy:
- Internal carotid artery dissection
Unilateral mydriasis ± 3rd N. paralysis:
- Aneurysm compressing the third nerve
Patients avoid lying flat:
- SAH
- Intracranial hypertension
- Cerebral venous thrombosis
- Acute sinusitis
Patients avoid standing up:
- Intracranial hypotension
- Cerebellar stroke (see vertigo)
Papilloedema:
- Intracranial hypertension
Arterial hypertension:
- Subarachnoid haemorrhage, eclampsia, PRES, RCVS
Electrocardiographic abnormalities:
Asymmetrical BP at upper limbs:
Investigations
- ALL ? SAH should be discussed with the EM duty registrar or consultant. Many require CT ± LP (CDU)
Thunderclap - normal CT & LP
- Arterial Dissection (aorta, carotid, vertebral)
- Symptomatic aneurysm (Ⅲ CN palsy)
- RCVS
- Cerebral v. thrombosis (↑opening pressure)
- "Pituitary apoplexy"
- Intracranial hypotension (↓opening pressure)
- Temporal arteritis
- Myocardial ischaemia
Links
- Clinical Review. Thunderclap headache. BMJ 2013; 346
- SAH in the ED (SHED). https://doi.org/10.1136/emermed- 2024-214068