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High-altitude cerebral oedema - HACO

Critical urgency
-Very severe

Cerebral oedema is part of acute mountain sickness (AMS), that occurs above 2500 metres.

Fluid accumulates in the brain cells due to an increased permeability of the blood capillaries caused by less pressure of oxygen. A lack of acclimatisation, dehydration or a previous episode can prompt its .

The symptoms are progressive with headache, nausea, vomiting, fatigue, dizziness and irritability.

It is a life-threatening emergency that requires immediate treatment by initiating descent and the use of oxygen therapy and dexamethasone.

Bibliographic references
  1. Scott A Gallagher, MD. Peter Hackett, MD. Jonathan M Rosen, MD. High altitude illness: Physiology, risk factors, and general prevention. UpToDate. Apr 15, 2015.
  2. Scott A Gallagher, MD. Peter Hackett, MD. Acute mountain sickness and high altitude cerebral edema. UpToDate. Mar 03, 2016.
  3. Wilson MH, Newman S, Imray CH. The cerebral effects of ascent to high altitudes. Lancet Neurol 2009; 8:175.
  4. Bailey DM, Bärtsch P, Knauth M, Baumgartner RW. Emerging concepts in acute mountain sickness and high-altitude cerebral edema: from the molecular to the morphological. Cell Mol Life Sci 2009; 66:3583.
  5. Schoene RB. Illnesses at high altitude. Chest 2008; 134:402.
Author
Dr. Oscar Garcia-Esquirol
Copyright
© TeckelMedical 2026

Symptoms

    Neurological symptoms: impaired speech, physical strength or feeling

    Coma

    Difficulty coordinating movements

    Change in mood and/or behaviour

    Constant headache

Pre-hospital care recommendations

Descend below clearance height (< 2.500 metres).
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