Share Facebook Twitter LinkedIn Email Telegram WhatsApp A severe and potentially fatal condition occurring at high altitudes where the brain swells, leading to symptoms like severe headache, confusion, and altered mental status. Synonyms: HACERelated Articles: Big Mountain BalanceA Himalayan OdysseyPractical Advice for Using O2 Sat Meters on ExpeditionsHow Long Does it Take to Climb Mount EverestIntroduction to Altitude