[Headache emergencies are easily overlooked]

This article presents secondary headache syndromes caused by life-threatening disease as well as symptomatic headaches requiring immediate treatment to prevent irreversible deficits. Clinical signs and symptoms indicating a secondary headache syndrome are summarized in the so-called SNOOP list (SNOOP: systemic symptoms, neurological symptoms, acute onset, older patients and previous history). The main topic of this publication is the diagnostic procedure, with a discussion of the pitfalls of computed tomography and magnetic resonance imaging investigations and the specificities of other methods such as lumbar puncture and duplex sonography.