Morphological Brain Changes after Climbing to Extreme Altitudes—A Prospective Cohort Study

Abstract

BackgroundFindings of cerebral cortical atrophy, white matter lesions and microhemorrhages have been reported in high-altitude climbers. The aim of this study was to evaluate structural cerebral changes in a large cohort of climbers after an ascent to extreme altitudes and to correlate these findings with the severity of hypoxia and neurological signs during the climb.MethodsMagnetic resonance imaging (MRI) studies were performed in 38 mountaineers before and after participating in a high altitude (7126m) climbing expedition. The imaging studies were assessed for occurrence of new WM hyperintensities and microhemorrhages. Changes of partial volume estimates of cerebrospinal fluid, grey matter, and white matter were evaluated by voxel-based morphometry. Arterial oxygen saturation and acute mountain sickness scores were recorded daily during the climb.ResultsOn post-expedition imaging no new white matter hyperintensities were observed. Compared to baseline testing, we observed a significant cerebrospinal fluid fraction increase (0.34% [95% CI 0.10–0.58], p = 0.006) and a white matter fraction reduction (-0.18% [95% CI -0.32–-0.04], p = 0.012), whereas the grey matter fraction remained stable (0.16% [95% CI -0.46–0.13], p = 0.278). Post-expedition imaging revealed new microhemorrhages in 3 of 15 climbers reaching an altitude of over 7000m. Affected climbers had significantly lower oxygen saturation values but not higher acute mountain sickness scores than climbers without microhemorrhages.ConclusionsA single sojourn to extreme altitudes is not associated with development of focal white matter hyperintensities and grey matter atrophy but leads to a decrease in brain white matter fraction. Microhemorrhages indicative of substantial blood-brain barrier disruption occur in a significant number of climbers attaining extreme altitudes.

Combined fractional anisotropy and subcortical volumetric abnormalities in healthy immigrants to high altitude: A longitudinal study

“…From surface-based morphology analysis, we revealed that there were no significant differences of cortical volume between the Year 2 and the baseline in both experimental and control group. This agrees with previous findings by Kottke et al (2015), which evaluated the occurrence of structural cerebral changes in a cohort of 38 recreational HA climbers and did not detect structural changes (Kottke et al, 2015). However, some fMRI studies found that compared with the SL individuals, HA young adults who were born and grew up at plateau had decreased volume in the left insula, left inferior parietal gyrus, and right superior parietal gyrus and increased in the left precentral cortex and multiple sites in cerebellar cortex (Usui et al, 2004;.…”

Recruitment of non‐perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m

“…Details on subject selection criteria are provided elsewhere (Kottke et al . ). All subjects underwent examination of the sublingual microcirculation by handheld vital microscopy (HVM) before and after topical application of nitroglycerin, alongside a clinical examination, echocardiography, and venous and arterial blood sampling for baseline assessment at the University Hospital of Bern (sea level, SL; 553 m).…”

Does permissive hypoxaemia during extracorporeal membrane oxygenation cause long-term neurological impairment?

“…Studies of oxygenation in healthy participants on high altitude expeditions have shown that it is possible to tolerate hypoxemia quite well [37]. However, there seems to be a risk for cerebral lesions and microhemorrhages in association with high altitude, i.e., hypobaric hypoxemia [38]. Nevertheless, these conditions are difficult to compare with those seen in patients with an underlying disease suffering from hypoxemic respiratory failure.…”

“…Five patients were previous healthy. Five patients presented with co-morbidities and had a median body mass index (BMI, kg/m 2 ) of 35 (31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42). A person with a BMI of 30 or more is generally considered obese according to the world health organization's (WHO) definition [44].…”