Red flags for secondary headaches: challenges in clinical practice

Introduction The World Health Organization (WHO) ranks migraine as one of the top 20 causes of impaired healthy life years per year worldwide. Migraine alone is responsible for about 400,000 lost workdays per year per one million inhabitants in developed countries. Headache is probably among the five most important causes of disability worldwide.  Method This literature review was carried out by searching the Pubmed, Lilacs and Scopus databases, using the following Health Science Descriptors (DeCS) of the Virtual Health Library and in particular the current data collected by the WHO or health entities in the various countries: "secondary headaches" AND "red flags" AND "review". Articles published in Portuguese and English were selected. The eligibility criteria defined for the inclusion of articles were studies that addressed the chosen theme.  Results The use of "Red Flags" in clinical practice is of considerable relevance. The combination of "Red Flags", anamnesis, physical examination, laboratory, and imaging examination accentuate the probability of predicting the etiology that may underlie the onset of a secondary headache.  However, despite this widely useful screening tool, there are still gaps in the prognosis.  Conclusion Much remains unclear as there is a lack of prospective epidemiological studies. In addition, some "Red Flags" such as pattern change are poorly elucidated. Large-scale studies are needed due to the low incidence of many secondary causes. New patients with headache should be screened using the SNNOOP10 list to increase the likelihood of detecting a secondary cause.