The R-Threshold of the Quick Component: A New Measure in Electronystagmography

Abstract

Vestibular imbalance affects the eyes through the fasciculus longitudinalis medialis and oculomotor nuclei. As regards vestibular excitation, eyes could theoretically be turned around and around until balance is achieved. However, since physical and anatomical limitations do not allow such turning around, the eyes could be held in the utmost lateral position, in the position of conjugated deviation. Nevertheless, the eyes are not held in this position of conjugated deviation, since the compensatory central component brings the eyes back to the position of azimuth zero. Logically, this should depend on physical limitations and on the tension of the eye muscles which transmit information to the central structures via the proprioceptive afferent paths. The speed of the slow component and other elements also plays a certain role here. It seems that we are faced with a great task of determining all these elements in order to define the point where the returning quick eye movement begins.