Emergent Causes of Headache and Associated Risk Factors Carbon monoxide poisoning - Breathing in enclosed or confined spaces with engine exhaust or ventilation of heating equipment - Multiple household members with the same symptoms - Wintertime and working around machinery or equipment producing carbon monoxide (eg, furnaces) Meningitis, encephalitis, abscess - History of sinus or ear infection or recent surgical procedure - Immunocompromised state - General debilitation with decreased immunologic system function - Acute febrile illness—any type - Extremes of age - Impacted living conditions (eg, military barracks, college dormitories) - Lack of primary immunization Temporal arteritis - Age > 50 - Females more often than males (4:1) - History of other collagen vascular diseases (eg, systemic lupus) - Previous chronic meningitis - Previous chronic illness, such as tuberculosis, parasitic or fungal infection Glaucoma—acute angle closure - Not associated with any usual or customary headache patterns - History of previous glaucoma - Age >30 - History of pain increasing in a dark environment Increased intracranial pressure - History of previous benign intracranial hypertension - Presence of cerebrospinal fluid (CSF) shunt - History of congenital brain or skull abnormalities - Female gender - Obesity Cerebral venous sinus thrombosis - Female gender - Pregnancy, peripartum, hormone replacement therapy or oral contraceptive use - Prothrombotic conditions Reversible cerebral vasoconstriction syndrome - Episodic sudden severe pain, with or without focal neurological findings or seizure - Recurrent episodes over a period up to several weeks - Exposure to adrenergic or serotonergic drugs - Postpartum state Subarachnoid hemorrhage (SAH) - Sudden and severe pain; "worst headache of life" - Acute severe pain after sexual intercourse or exertion - History of SAH or cerebral aneurysm - History of polycystic kidney disease - Family history of SAH - Hypertension—severe - Previous vascular lesions in other areas of the body - Young and middle-aged Subdural hematoma - History of alcohol dependency with or without trauma - Current use of anticoagulation Epidural hematoma - Traumatic injury - Lucid mentation followed by acute altered mentation or somnolence - Anisocoria on physical examination #headache #redflags #signs #symptoms #differential #emergency #diagnosis
