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High Altitude Cerebral Edema

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Other Names

  • High Altitude Cerebral Edema (HACE)

Background

History

Epidemiology

  • Occurs in less than 1% of visitors to altitude (need citation)

Pathophysiology

  • General
    • Serious, life threatening condition
    • Typically occurs at very high or extreme altitudes, but has been documented below 3000 m[1]
    • It should be considered in anyone experiencing AMS, regardless of symptoms
    • Onset is typically several days after arriving at altitude, but can occur within hours

Etiology

  • Cerebral Edema
    • Develops following cerebral vasodilation secondary to hypoxia
    • Hypoxemia results in overperfusion of microvasculature, increased hydrostatic pressure, leakage from capillaries[2]
    • Autopsies reveal edema
    • Magnetic resonance imaging (MRI) studies demonstrate white matter changes splenium of the corpus callosum (consistent with edema)[3]

Associated Conditions


Risk Factors


Differential Diagnosis

  • Neurologic/ Ophtho
    • Migraine
    • Transient Ischemic Attack
    • Stroke
    • Cerebral Venous Thrombosis
    • Cranial nerve palsies
    • Ophthalmological disturbances (cortical blindness, retinal hemorrhage)
    • Cognitive slowing
    • Emotional liability
  • Metabolic
  • Environmental

Clinical Features

  • History
    • Symptoms are typically similar to those with AMS, but more severe
    • Includes headache, nausea and vomiting, fatigue,
  • Physical Exam
    • Ataxia
    • Altered consciousness (confusion, irrational behavior, lethargy, impaired cognition, stupor, and coma)
    • Papilledema
    • Retinal hemorrhage
    • Focal neurologic deficits
  • Special Tests

Evaluation

  • No special tests are required to diagnose HACE
    • It should be the presumed diagnosis in any patient with neurological symptoms after ascending to altitude

Classification

  • Currently no classification exists

Management

Prevention

Treatment

  • Immediate Descent
    • By helicopter if possible
  • Supplemental Oxygen
    • Maximum flow rate to maintain oxygen saturation above 90%
  • Dexamethasone
    • 8 mg loading dose followed by 4 mg every 6 hours
  • Portable Hyperbaric Chamber
    • Should be used if available, especially if evacuation is delayed
    • If patient has nausea and vomiting or requires airway management, this option remains challenging
    • Should not delay descent

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play/ Work

  • Little evidence is present to guide team physicians
    • Clinical judgement is paramount
  • Recovery from HACE is highly variable[4]
    • Ranges from days to up to 12 weeks
    • Immediate return is not advised
  • Return to altitude where HACE developed will need to occur at a slower pace
    • Staged ascent with stops along the way
  • Consider prophylaxis with Acetazolamide

Complications and Prognosis

Prognosis

  • Recovery
    • Full recovery occurs in most patients
    • Permanent neurologic impairment an occur

Complications

  • Death
    • Occurs due to brain herniation from unchecked cerebral edema
  • Neurologic Defecits

See Also


References

  1. Hackett PH, Roach RC. High-altitude illness. In: Auerbach PS, editor. Wilderness Medicine, 5th ed., Philadelphia: Mosby; 2007, p. 2Y35.
  2. Hackett PH, Roach RC. High-altitude illness. N Engl J Med 2001; 345: 107–114.
  3. Hackett PH, Yarnell PR, Hill R, Reynard K, Heit J, McCormick J. High-altitude cerebral edema evaluated with magnetic resonance imaging: clinical correlation and pathophysiology. JAMA 1998; 280: 1920–1925.
  4. Yarnell PR, Heit J, Hackett PH. High-altitude cerebral edema (HACE): the Denver/Front Range experience. Semin. Neurol. 2000; 20:209Y17.
Created by:
John Kiel on 30 June 2019 23:00:12
Authors:
Last edited:
24 April 2022 12:36:41
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