Effects of Galvanic Stimulation on Spontaneous Nystagmus in Meniere's Disease and Vestibular Neuritis: A Preliminary Study

Jeong, Seong Hae; Kim, Ji Soo

Abstract

BACKGROUND AND OBJECTIVES
Galvanic vestibular stimulation (GVS) is known to induce nystagmus, ocular torsion, a tilt of subjective visual vertical, and perceptual and postural shift. The aim of this study was to compare the findings of GVS among the patients with spontaneous nystagmus (SN) caused by Meniere's disease (MD) or vestibular neuritis (VN).
MATERIALS AND METHODS
Three-dimensional video-oculography was performed without fixation in 4 patients with MD and 2 with VN, as diagnosed by history, independent vestibular function tests and neuroimaging. We recorded the eye-movements in response to bilateral, bipolar, and surface GVS (2.5~3 mA) for 30 seconds, and analyzed mean slow phase velocity of SN.
RESULTS
Of the 4 patients with MD, two exhibited a suppression of the left beating SN during anode stimulation of left mastoid and an augmentation of the nystagmus during cathode stimulation of left mastoid. The same patterns of galvanic modulation were observed in the other 2 patients with right beating SN due to MD. In contrast, the patients with VN showed an absent or decreased response to GVS.
CONCLUSION
In MD, the responses to GVS were preserved while the responses were impaired in VN. These results suggest that the irregular vestibular fibers, which are sensitive to GVS, are relatively spared in MD. In contrast, both regular and irregular fibers appear to be damaged in VN. GVS may be helpful in discriminating MD from VN, especially when the patients presented without auditory symptoms.