High altitude cerebral edema


  • Also known as HACE
  • Progressive neurologic deterioration in someone with acute mountain sickness or HAPE (due to ↑ ICP)
  • Almost never occurs at <8,000ft

Clinical Features

  • Altered mental status, ataxia, gait disturbance, stupor (most sensitive findings)
    • Progresses to coma if untreated
  • Uncertain mechanism, presumed cause is hypoxia leading to cerebral edema
  • Headache, nausea/vomiting (not always present)
  • Focal neuro deficits may be seen (3rd/6th CN palsies)
  • Seizures are rare

Differential Diagnosis

High Altitude Illnesses


  • Typically a clinical diagnosis

Expected SpO2 and PaO2 levels at altitude[1]

Altitude SpO2 PaO2 (mm Hg)
1,500 to 3,500 m (4,900 to 11,500 ft) about 90% 55-75
3,500 to 5,500 m (11,500 to 18,000 ft) 75-85% 40-60
5,500 to 8,850 m (18,000 to 29,000 ft) 58-75% 28-40


  • Immediate descent is the treatment of choice
  • If descent not possible use combination of:
    • Supplemental O2 (goal SpO2 90%)[2]
    • Supportive hyperventilation
    • Dexamethasone 8mg initially (PO, IM, or IV), then 4mg q6hr
    • Acetazolamide 250mg BID (better as ppx)
    • Hyperbaric bag (Gamow bag) if available


See Also

  • High Altitude Medicine


  1. Gallagher, MD, Scott A.; Hackett, MD, Peter (August 28, 2018). "High altitude pulmonary edema". UpToDate. Retrieved May 2, 2019.
  2. Hackett PH, Roach RC. High altitude cerebral edema. High Alt Med Biol 2004; 5:136-146.
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