Vestibular compensation.

Abstract

Regulation of the human equilibrium differs from the other, mostly linear, human senses. It consists of a multitude of receptors and an interrelated network that is necessary for data processing as well as for regulatory processes. Thus, the human equilibrium system represents a mixture of hardware and related software interactions. The input is also named the "equilibrium tetrade" (1-3), and comprises vision, vestibular inertia acceleration perception, proprioception and hearing. In the case of various types of lesion, one has to deal with a variety of morphological as well as mostly functional reparations. Amongst others these consist of restitution, adaptation, suppression, habituation and compensation. In order to objectively investigate the type of ongoing compensatory reparation within the complex network functions of the equilibrium system, we need to apply the so-called complex vestibular equilibrium tests. These allow us to quantitatively check for the response outputs after varying stimulus loadings, as well as after spatial or temporal stimulus interferences. For testing the equilibrium system under the condition of varying stimulus intensity impacts, the vestibular stimulus response intensity comparison test (VSRIC) is applied (4-6). Spatial stimulus interference between the ocular and the vestibular system is checked by means of the calorisation pendulum interference test (CPIT) (1, 2, 5, 7-9). In the case of temporal stimulus interference testing it is assumed that a memory copy of earlier stimuli influences successive reactions. Thus phenomena such as learning or habituation can be induced. Temporal stimulus interference is tested by means of the caloric adaptation cyclogram (CAC) (2-5, 10, 11).