Hearing, vestibular reactivity and postural stability after 21-day period at high altitude

Purpose: The exposure to high-altitude hypobaric hypoxic environment results in a lot of organic responses and adaptation mechanisms. Depending on the absolute altitude and the duration of exposure, some effects, named mountain sickness, are evident, including cardiovascular and pulmonary responses and cerebral dysfunctions. Methods: In this study we analyzed the hearing sense, vestibular reactivity and the postural stability of seven climbers before and after a 21-day period of exposition to hypobaric hypoxia (over 5,000 m). To obtain this goal we assayed: audiometric and bithermal caloric tests, and the postural stability by static stabilometry. Results: Our data revealed that all subjects showed normal values in all tests. There was a slight, but not significant, neurosensorial hypoacusia in hearing capacity, even if at different frequency and ear. After the hypobaric hypoxia exposition, the caloric test did not reveal significant differences in pre vs. post analyses, even if two subjects reported a transitory positional vertigo at 12 and 13 days of expedition. Interestingly, the climbers significantly improved their stability not involving the visual perception. Conclusions: This experience suggests that the high altitude could transiently modulate the vestibular function without any pathological consequences, and it improved the stability probably integrating the proprioceptive stimuli and muscle strength also as a consequence of physical efforts.