Hallmarks of headache disorders: part 5 - secondary headaches.

BACKGROUND AND AIM: Headache is a common symptom that can be frequently caused by multiple secondary causes. Every person with headache fears to have a severe cause, and healthcare providers must be trained to identify which patients may suffer from these. This manuscript continues the series of hallmarks of headache disorders describing the state of the art regarding the pathophysiology, clinical aspects, diagnosis, red flags, biomarkers, acute treatment, and preventive therapies of secondary headache disorders. MAIN RESULTS: Identification of secondary headache disorders is challenging, due to the large number of different causes and varied phenotypic presentations. Prompt recognition and targeted treatment can save patients’ lives and prevent chronic sequelae. Changes in the headache phenotype or new-onset neurological or systemic symptoms may reflect the occurrence of a subsequent complication and require further investigation. In patients who develop a persistent headache following to the secondary cause a phenotypic-based acute and preventive treatment is usually recommended. CONCLUSIONS: Secondary headache disorders are major contributors to the global burden of headache. Their true prevalence is the hidden part of the iceberg, but their consequences are evident. Research on secondary headache disorders could be key in the understanding of primary headache disorders pathophysiology.