Brain effects of high-altitude sickness retained long term

Nov 28 2012

By Helen Albert, Senior medwireNews Reporter

Mountaineers who experience high-altitude cerebral edema (HACE) often retain traces of the bleed in their brains for many years afterward, show study findings.

Michael Knauth (Medical University of Goettingen, Germany), who presented the research at the Radiological Society of North America Annual Meeting in Chicago, Illinois, USA, said that while he and his colleagues do not think that people who have survived HACE need to give up climbing, "mountaineers who have already experienced HACE once should acclimatize to the altitude very slowly."

Knauth and team recruited 36 mountaineers who had a history of altitude sickness above 2300 m. Of these, seven had high-altitude illness, 11 had severe acute mountain sickness (AMS), eight had high-altitude pulmonary edema alone, and 10 had HACE alone.

On magnetic resonance imaging (MRI), definite microhemorrhages were observed in the brains of eight of the 10 HACE survivors, with uncertain results observed for the other two patients. However, only two of the other 26 climbers had evidence of brain microhemorrhages.

Most of the microhemorrhages were observed in the corpus callosum, although cerebral white matter was affected in a few of the more severe HACE cases.

HACE is a severe and often fatal condition that can affect mountaineers, hikers, and travelers at high altitude. It often begins as AMS.

"It was previously thought that HACE did not leave any traces in the brains of survivors," commented Knauth in a press statement.

"Our studies show that this is not the case. For several years after, microhemorrhages or microbleeds are visible in the brains of HACE survivors."

He added: "We will further analyze our clinical and MRI data on patients with acute mountain sickness, which is thought to be a precursor of HACE."

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