Bilateral vestibulopathy

Abstract

Bilateral vestibular failure (BVF) is a rare disorder of the peripheral labyrinth or the eighth nerve which has various aetiologies. It is either acquired or congenital, or familial or sporadic. BVF occurs simultaneously or sequentially in both ears, and takes either an abrupt or slowly progressive course. A chronic bilateral loss of vestibular function is surprisingly well tolerated. This is due to the fact that spatial orientation, posture, and eye movements are mediated by redundant multisensory processes (p. 3), which can in part compensate for each other’s deficiencies. Moreover, there is no continuing distressing vertigo, spontaneous nystagmus, or postural falls, which are typical signs of a vestibular tone imbalance caused by acute unilateral lesions. The key symptoms are oscillopsia during locomotion or head movements and unsteadiness, particularly in the dark. The entity was first described by Dandy (1941) in patients who had undergone bilateral vestibular neurectomies. Generally patients with BVF are first referred not only for assessment of dizziness and disequilibrium, but also for examination of ocular motor disorders, ataxia, or hearing loss, conditions in which BVF is often not suspected prior to investigation (Rinne et al. 1995).