Effects of unilateral dysfunction of the inferior vestibular nerve system on postural stability.

OBJECTIVE

To investigate whether disorders of the inferior vestibular nerve (IVN) system affect postural stability.

METHOD: Two-legged stance tasks were performed by patients with unilateral peripheral vestibulopathy (n=108) in four conditions: eyes open or eyes closed, with or without foam rubber. We examined six parameters: the velocity of movement of the center of pressure and the envelopment area determined by tracing the movement in the eyes closed/foam rubber condition, Romberg's ratio of velocity and area with foam rubber, and the foam ratios (ratios of a measured parameter with to without the foam rubber) of velocity and area with eyes closed.

RESULTS

The values of all six parameters were significantly higher in patients with unilateral vestibulopathy whose cervical vestibular evoked myogenic potentials (cVEMPs) were abnormal compared with healthy controls (p<0.01). Four of the six parameters showed significantly higher values (p<0.05) in patients with unilateral abnormal cVEMPs in the presence of normal caloric responses compared with the controls.

CONCLUSIONS

Foam posturography is useful for making a preliminary assessment of unilateral vestibulopathy with abnormal cVEMPs. Selective damage of the unilateral IVN system could affect postural stability.

SIGNIFICANCE: We proved the influence of the disorder of the IVN system on postural stability.