Marcelo M Valença1,2, Daniella A de Oliveira1. 1. Department of Neuropsychiatry, Neurology and Neurosurgery Unit, Federal University of Pernambuco, Brazil. 2. Neurology and Neurosurgery Unit, Hospital Esperança, Brazil.
Abstract
BACKGROUND: There is no agreement on a single cutoff point or prevalence for regarding a given disease as rare. The concept of what is a rare headache disorder is even less clear and the spectrum from a very frequent, frequent, occasional to rare headache syndrome is yet to be established. OBJECTIVE: An attempt has been made to estimate the lifetime prevalence of each of the headache subtypes classified in the ICHD-II. METHOD: Using the ICHD-II, 199 different headache subtypes were identified. The following classification was made according to the estimated lifetime prevalence of each headache disorder: very frequent (prevalence >10%); frequent (between 1 and 10%); occasional (between 0.07 and 1%); and unusual or rare (<0.07%). RESULTS: One hundred and fifty-four of 199 (77%) were categorized as unusual headache disorders, 7/199 (4%) as very frequent, 9/199 (5%) as frequent, and 29/199 (15%) as occasional forms of headache disorder. CONCLUSION: The unusual headache syndromes do not appear to be as infrequent in clinical practice as has been generally believed. About three-fourths of the classified headache disorders found in the ICHD-II can be considered as rare. This narrative review article may be regarded as an introduction to the concept of unusual headaches and a proposed classification of all headaches (at least those listed in the ICHD-II).
BACKGROUND: There is no agreement on a single cutoff point or prevalence for regarding a given disease as rare. The concept of what is a rare headache disorder is even less clear and the spectrum from a very frequent, frequent, occasional to rare headache syndrome is yet to be established. OBJECTIVE: An attempt has been made to estimate the lifetime prevalence of each of the headache subtypes classified in the ICHD-II. METHOD: Using the ICHD-II, 199 different headache subtypes were identified. The following classification was made according to the estimated lifetime prevalence of each headache disorder: very frequent (prevalence >10%); frequent (between 1 and 10%); occasional (between 0.07 and 1%); and unusual or rare (<0.07%). RESULTS: One hundred and fifty-four of 199 (77%) were categorized as unusual headache disorders, 7/199 (4%) as very frequent, 9/199 (5%) as frequent, and 29/199 (15%) as occasional forms of headache disorder. CONCLUSION: The unusual headache syndromes do not appear to be as infrequent in clinical practice as has been generally believed. About three-fourths of the classified headache disorders found in the ICHD-II can be considered as rare. This narrative review article may be regarded as an introduction to the concept of unusual headaches and a proposed classification of all headaches (at least those listed in the ICHD-II).