RESUMEN
The perception of verticality is mainly based on utricular afferent signals and central processing of the transmitted signals. However, there are also extracranial receptors that make a considerable contribution to the perception of verticality. With the subjective visual vertical (SVV) for the utricle and the subjective trunk vertical (STV), two different parameters are available that are not fully understood in terms of their response to physiologic and pathologic changes. The aim of this work was to determine SVV and STV under certain positions of the head and trunk as well as under the influence of Menière's disease (MD) as a chronic vestibular disease. In a prospective clinical study, 26 patients with MD and 39 healthy volunteers were recruited. Subjects were examined with CSVV glasses and with the three-dimensional trunk excursion chair, while head and torso positions were varied. In both groups, SVV determination is clearly more accurate with an earth-vertical head alignment than with a lateral head tilt (right: MM and control group: pâ¯= 0.001; left: MM pâ¯= 0.001, control group pâ¯= 0.000). If the torso is deflected laterally and the head is held straight, the SVV is significantly more accurate (left pâ¯= 0.003, right pâ¯= 0.015). The SRV was not affected by the presence of unilateral MD, while pathologic SVV values, if present, indicated the affected side. The results of our study support the assumption that in addition to SVV, SRV is an independent parameter for verticality perception and differs from the SVV in terms of lateralizing a peripheral vestibular deficit. These results suggest that the STV may depend not only on utricular function but also on extracranial afferent signals, and not be significantly altered by the presence of a hydropic peripheral vestibular lesion.