Directional preponderance of nystagmus and excitement of autonomic nervous system.

Since autonomic nervous dysfunction is the most common predetermining factor of vertigo, the functional relationship between these two systems was studied using the rabbits. Cervical sympathectomy or electric stimulation of the superior cervical ganglion were given to the animal on one hand, and modulation of the blood pressure and electric stimulation of the hypothalamus were done, on the other. These manoeuvres rarely induced asymmetry of the vestibulo-ocular reflex (VOR). However, when other pairs of conditions were combined, such as cervical ganglion stimulation and BP modulation, or sympathectomy and hypothalamic stimulation, directional preponderance of VOR became prominent. This experimental model seems to explain the mechanism of vertigo observed.