Correspondence

Transient Global Amnesia at High Altitude

N Engl J Med 1999; 340:1444May 6, 1999

Article

To the Editor:

Transient focal neurologic conditions at high altitude without cerebral edema are uncommon but alarming. We describe two cases of isolated, transient global amnesia at very high altitude.

The first patient, a healthy 21-year-old man with no history of migraine, flew to Mexico City (elevation, 2241 m). He ascended by vehicle to 3950 m over a period of four days to begin an ascent of Popocatépetl (elevation, 5452 m). After a day of rest, he climbed to an altitude of 4400 m without problems. The next morning, the climber appeared startled and confused. Though alert, he was unable to recall the date, the location, or his purpose for being on a volcano. He was able to state his name, however, and after prompting, was able to recognize his companions. The results of an examination were normal, with no ataxia or dyspnea at rest. A descent of 450 m brought gradual resolution of the amnesia. During the next six days, the climber ascended two other volcanoes higher than 5200 m without problems. At a one-year follow-up examination, he was in good health.

The second patient, a healthy 60-year-old man with no history of migraine, dementia, or cerebral vascular disease, drove to an altitude of 1650 m and hiked to 3000 m to begin a solo ascent of Mount Rainier (4422 m). At dawn the next day, he continued climbing to 3760 m, where he was later found resting. The climber was alert and able to state his name, but he was unable to recall the date, his home address, or the current U.S. president. Results of an examination were normal, with no ataxia or dyspnea at rest. After a 760-m descent, he became fully oriented, and the amnesia resolved. At a two-month follow-up interview, he reported good health.

Transient global amnesia is a syndrome of severe, forgetful confusion characterized by retrograde memory loss and total disorientation except for self-identity, followed by gradual resolution. Commonly, the presumed cause is transient ischemia.1 The relative hypoxia associated with exposure to very high altitudes may precipitate transient global amnesia in some persons. Memory is critically served by the limbic cortex and involves the temporal hippocampal axis, and even moderate hypoxia due to high altitude may impair memory.2

Increased intracerebral pressure caused by cerebral edema at high altitude could have resulted in the amnesia, but it is unlikely as an isolated finding, and neither of the patients we describe had evidence of severe altitude illness. The amnesic episodes developed in association with rapid ascent to very high altitudes and resolved during descent, suggesting that exposure to high altitude may have precipitated or caused the amnesic events.

Persons with neurologic conditions at high altitudes benefit from immediate descent, supplemental oxygen, and possibly carbon-dioxide rebreathing if there are no signs of increased intracerebral pressure. Patients with persistent symptoms after descent require prompt evacuation and thorough evaluation.3

James A. Litch, M.D., D.T.M.H.
Rachel A. Bishop, M.B., Ch.B., D.T.M.H.
Kunde Hospital, Kathmandu, Nepal

3 References

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   Kennedy RS, Dunlap WP, Banderet LE, Smith MG, Houston CS. Cognitive performance deficits in a simulated ascent climb of Mount Everest: Operation Everest II. Aviat Space Environ Med 1989;60:99-104
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   Litch JA. Subarachnoid hemorrhage at high altitude. West J Med 1997;167:180-181
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Citing Articles (8)

Citing Articles

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   Mira Bucuk, Zoran Tomic, Lidija Tuskan-Mohar, David Bonifacic, Marina Bralic, Ante Jurjevic. (2008) Recurrent Transient Global Amnesia at High Altitude. High Altitude Medicine & Biology 9:3, 239-240
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   Javier Virues-Ortega, Eduardo Garrido, Casimiro Javierre, Karen C. Kloezeman. (2006) Human behaviour and development under high-altitude conditions. Developmental Science 9:4, 400-410
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   Javier Virus-Ortega, Gualberto Buela-Casal, Eduardo Garrido, Bernardino Alczar. (2004) Neuropsychological Functioning Associated with High-Altitude Exposure. Neuropsychology Review 14:4, 197-224
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   Buddha Basnyat, Tianyi Wu, Jeffrey H. Gertsch. (2004) Neurological Conditions at Altitude That Fall Outside the Usual Definition of Altitude Sickness. High Altitude Medicine & Biology 5:2, 171-179
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   Buddha Basnyat. (2002) Case Report: Delirium at High Altitude. High Altitude Medicine & Biology 3:1, 69-71
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   A. Kettaneh, C. Gobron, O. Fain, S. Mohib, M. Thomas. (2001) Calculi and memory. European Journal of Neurology 8:2, 195-196
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7. 7

   Jon S. Simons, John R. Hodges. (2000) Transient global amnesia. Neurocase 6:3, 211-230
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8. 8

   James A. Litch, Rachel A. Bishop. (2000) High-altitude global amnesia. Wilderness & Environmental Medicine 11:1, 25-28
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