Table 2.

SNOOP4 mnemonic to assess for secondary causes of headache

Systemic symptoms and signsPossible causes
Fever, rigors, sweats, weight lossInfection, giant cell arteritis, neoplasia
History of immunosuppression or cancer
PregnancySecondary vascular cause, especially cerebral venous sinus thrombosis
Family history of intracranial aneurysmSubarachnoid haemorrhage
ObesityIdiopathic intracranial hypertension
Neurological symptoms and signs
Focal neurological deficitAny secondary cause (migraine aura may also cause focal deficit, but this evolves over minutes and usually resolves within 1 hour)
MeningismInfection, subarachnoid haemorrhage
Visual obscurations, pulsatile tinnitusIdiopathic intracranial hypertension, mass lesions
Onset sudden
Did the pain reach maximum intensity within 60 seconds (thunderclap headache)?Secondary vascular causes
Onset for the first time over 50 years ageAny secondary cause (especially giant cell arteritis)
Progressive headache (in intensity or duration of episodes)Consider possibility of neoplasia or medication-overuse headache
Precipitated by Valsalva manoeuvreChiari malformation, intracranial structural lesion – especially posterior fossa; intracranial hypotension
Postural relationship
Worse when standingIntracranial hypotension
Worse when lyingRaised intracranial pressure
PapilloedemaRaised intracranial pressure
  • Secondary causes include intracranial infection, inflammation including giant cell arteritis, neoplasia and vascular disease. Vascular disease includes stroke, subarachnoid haemorrhage, venous sinus thrombosis, reversible cerebral vasoconstriction syndrome and arterial dissection. Adapted from Dodick.5