Altitude Illness: Cerebral Symptoms

Altitude Illness is a condition developed after having to ascent in a high altitude area. This illness is composed of variety of syndromes that results from loss of oxygen or hypoxia.  Altitude Illness can present with either cerebral or pulmonary symptoms. High – Altitude Cerebral Edema (HACE) and Acute Mountain Sickness (AMS) demonstrates cerebral symptoms or those that affect the brain. On the other hand, High – Altitude Pulmonary Edema (HAPE) presents pulmonary symptoms or that of the lung. There is no specific risk factor; anyone who is travelling in an altitude can be affected. No matter what the individual’s age, level of physical fitness, medical history or altitude experience is, one can acquire the illness.

Level of Altitude

High altitude – elevations over 1500 m (4900 ft)

  • Arterial oxygen saturation is maintained but with low PO2 that results in mild tissue hypoxia

Moderate altitude – elevations of 2000-3500 m (6600-11,500 ft)

  • Arterial oxygen saturation is maintained but with low PO2 that results in mild tissue hypoxia

Very high altitude – elevations of 3500-5500 m (11,500-18,000 ft)

  • Arterial oxygen saturation is not maintained and extreme hypoxemia can occur, especially during sleeping hours exercise
  • High – Altitude Pulmonary Edema (HAPE) is common in this altitude height

Extreme altitude – elevations over 5500 m

  • Body system declines and deteriorates


Acute Mountain Sickness (AMS) occurs on individuals who are not accustomed to an ascent in altitude. Usually, this manifests in the first 48 hours after rising to altitudes above 2500 m. According to the Lake Louise criteria, the diagnosis of AMS necessitates headache and at least one of the following symptoms:

  1. Headache (principal symptom, typically frontal and throbbing)
  2. Gastrointestinal symptoms
    • Anorexia
    • Nausea
    • Vomiting
    • Weakness
    • Light headedness
    • Fluid retention
    • Oliguria

High – Altitude Cerebral Edema (HACE) occurs when an individual travels to a very high altitude with elevations of 3500-5500 m (11,500-18,000 ft). The following symptoms indicate the presence of HACE:

    • Altered level of consciousness
    • Ataxia

Assessment and Diagnosis

The following tests verify AMS and HACE. These also rules out other illnesses with parallel syndromes:

  1. Head CT
    • Central neurologic findings or in atypical cases of suspected HACE
    • Specifically done to exclude other conditions
    • Head MRI
      • Increased T2 signal in the white matter of the splenium of the corpus callosum
      • Confirms HACE
      • Assesses the reason for having focal neurologic deficits


The following regimen are the management for altitude illness:

  1. Medications used as ordered:
    • Prophylactic medication for AMS (acetazolamide)
    • Analgesics (aspirin, acetaminophen, ibuprofen)
    • Carbonic anhydrase inhibitors
    • Antiemetic
    • Sedative hypnotics
    • Corticosteroids
    • Supportive care

Byron Webb Romero, RN, MSN

Finished BSN at Lyceum of the Philippines University, and Master of Science in Nursing Major in Adult Health Nursing at the University of the East Ramon Magsaysay Memorial Medical Center. Currently working at Manila Doctors College of Nursing as a Team Leader for Level I and II, Lecturer for Professional Nursing Subjects, and also a Clinical Instructor.

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