[New indications for the rotating chair test for side localization and determination of central compensation in vestibular function disorder]

Abstract

The horizontal vestibulo-ocular reflex was studied in normals and 35 patients with an acute or compensated unilateral peripheral vestibular deficit (PVD) in order to determine the efficacy of different response measures obtained from a rotating chair test in localizing the deficit side and defining its central compensation. The profiles of chair velocity and the visual fixation period were chosen in such a way that the slow phase velocity profiles were comparable to those obtained during caloric tests. Mean slow phase eye velocity measured during the culmination period elicited by constant chair acceleration of 5 degrees/s2 over 40 s was significantly reduced for rotations towards the side of an acute or compensated PVD. Per-rotatory gain asymmetry (after correcting for spontaneous nystagmus) was not always specific for the side of the deficit and often not significantly different from normal values in the compensated stage of the deficit. In combination both parameters (SPV and gain asymmetry) were reliable indicators (sensitivity 88%) of the underlying pathology and correctly localized the deficit side during the compensated state. The decay of post rotatory SPV followed a more rapid time course than normal during acute and compensated stages of the deficit. It may be concluded from those results that the rotating chair test is a valuable indicator of the presence and side of a peripheral vestibular deficit even when it has been centrally compensated.