Reduced voluntary non-visual suppression of the vestibulo-ocular reflex gain during nitrous oxide narcosis
Padoan, S.; Magnusson, M.; Akesson, M.; Ornhagen, H.
Aviation Space and Environmental Medicine 63(10): 875-880
1992
ISSN/ISBN: 0095-6562 PMID: 1417649 Document Number: 397952
The effect of subanesthetic nitrous oxide (N-2O) nrcosis (21%) on the vestibule-ocular reflex (VOR) and on voluntary non-visual suppression of the VOR was studied in 12 subjects, using a velocity step rotational test. Gain and time constant of the VOR were calculated by computer. During tests, the subjects were required either to perform mental arithmetic or to attempt to follow an imaginary target rotating with them in the dark. Voluntary non-visual suppression of gain was significantly reduced during exposure to N-2O, though there was no statistically significant effect of N-2O on gain per se. The time constant was unaffected either by voluntary suppression or by N-2O. The reducing effect of N-2O on voluntary non-visual suppression of VOR gain is assumed to be due to reduced alertness. Reduced voluntary non-visual suppression of VOR may imply reduced visual-vestibular interaction, which might be one explanation of the complaints of dizziness associated with fatigue or with ingestion of certain sedatives.