Table 1.

Commonly used acronym to that may signify the presence of an underlying pathological condition requiring neuroimaging.

	Stands for	Example	Differential diagnosis
S	Systemic symptoms	Fever, weight loss, fatigue	Infection (meningitis, encephalitis), giant cell arteritis, metastases, leptomeningeal carcinamatous
	Secondary risk factors	Malignancy, immunosuppression, HIV
N	Neurologic symptoms/signs	Focal neurologic deficits, altered consciousness, confusion	Mass lesion, stroke, hydrocephalus
O	Onset	Thunderclap, abrupt	Most common include: subarachnoid hemorrhage, reversible cerebral vasoconstriction syndrome, pituitary apoplexy, cerebral venous sinus thrombosis, vasculitis
O	Older (especially >50 years)	New onset, progressive headache	Mass lesion, giant cell arteritis
P	Positional	Change lying vs. sitting	Intracranial hypotension
	Prior	Different in quality from baseline	Mass lesion
	Papilledema	Visual obscurations	Idiopathic intracranial hypertension
	Precipitated by	Valsalva, coughing, sneezing	Posterior fossa lesion