Upper limb motor function at 5000 metres: determinants of performance and residual sequelae.

Little is known about the effects of age and symptoms of acute mountain sickness and the potential benefit of short term acclimatisation on fine motor performance at altitude. There is uncertainty about whether time spent at altitude results in permanent neurological sequelae. Nine hole pegboard tests were performed on a group of trekkers at sea level (n=61), after ascending to Kanchenjunga base camp (5100 m; n=46), and 20 weeks after return to sea level (n=43). Comparison of baseline and altitude times showed a mean slowing from 36.2 to 39.0 seconds, a 7. 8% deterioration in performance (p<0.0001), which was greatest in subjects aged 50 years or older (5.04 v 1.93 seconds, p=0.017), those tested within 24 hours of arrival at 5100 m (4.75 seconds, 13. 3% v 0.48 seconds, 1.3% p<0.001), and persons experiencing symptoms of acute mountain sickness (p=0.012), each of which were independent determinants of deterioration. Repeat pegboard testing at sea level after 20 weeks showed no significant change compared with baseline (p=0.68). This confirms the deleterious effects of altitude on fine motor function, emphasises the benefit of acclimatisation, and suggests that older persons and those with symptoms of acute mountain sickness are particularly susceptible. The risk of long term motor dysfunction after exposure to these relatively moderate altitudes seems to be small.