High Altitude Headache in Highlanders: A Hallmark Symptom of Chronic Mountain Sickness Related to Excessive Erythrocytosis? A Preliminary Report from the World's Highest City.

IntroductionHeadache is a hallmark symptom of chronic mountain sickness (CMS), a high altitude disease thought to be induced by excessive erythrocytosis (EE) in highlanders. Nevertheless, headache characteristics related to permanent high altitude residence remain understudied, as does the association between headache occurrence and hemoglobin concentration ([Hb]) in highlanders.MethodsA pilot cross-sectional study was conducted in La Rinconada, Peru (altitude 5100 m), over a 2-y period. During all comers' medical consultations, highlanders with no known history of chronic medical conditions (except EE/CMS) were questioned regarding headache symptoms. Headache characteristics were collected as well as clinical data and [Hb].ResultsHeadache prevalence was 61% (200 of 330 highlanders). Clinical characteristics of headache attacks (ie, location, onset, intensity, quality, and duration) were similar between highlanders with and without EE. In multivariate analysis, headache occurrence was associated with lower oxygen saturation (P<0.001), higher body mass index (P<0.001), and lower self-reported sleep duration (P<0.001) but not with [Hb] or sex.ConclusionsThe absence of a statistically significant association between headache occurrence and [Hb] questions the use of headache as a symptom reflecting EE in CMS highlanders.