[Interocular asymmetry of nystagmus and motion sickness]

Binocular video nystagmography was employed to study the human vestibulo-ocular reaction to the double rotation test used in medical flight certification to assess vestibulo-vegetative stability. Purpose of the investigation was to establish an interrelation between parameters of the nystagmus reaction to rotation and severity of motion sickness (MS). The total of 135 medically certified flying men aged 23 to 47 years were subject to testing by intermittent Coriolis accelerations accumulation according to Bryanov's procedure. The vestibulo-vegetative reaction was assessed by the criteria of vegetative reactivity and protective movements. The closed-mask binocular test was performed during and after rotation, It was shown that interocular nystagmus asymmetry is linked directly with MS severity. Asymmetry coefficients are proposed for unidirectional nystagmus during inclinations (C(ai)) and straightening (C(as)) and for time of convergent rotational nystagmus during inclinations (T(ci)) and straightening (T(cs)). Coefficients C(ai) and T(ci) were found to correlate with MS severity (p < 0.05). From the data of the investigation it was deduced that the mechanism of MS during double rotation amounts to intravestibular interlabyrinthine conflict.