Idiopathic bilateral vestibulopathy [(IBV), ORPHA 171684, ICD-10 H81.8] [
1] is an acquired bilateral peripheral vestibular hypofunction of unknown etiology, which was first proposed by Baloh et al. in 1989 [
1]. Synonyms of IBV include bilateral idiopathic loss of vestibular function (BILVF) [
2], idiopathic bilateral vestibular loss [
3], idiopathic bilateral vestibular hypofunction [
4] and idiopathic bilateral loss of vestibular function [
5]. The most common symptom of IBV is persistent unsteadiness, particularly in darkness and/or on uneven ground [
1]. The other main symptom is oscillopsia during head and body movements [
1]. IBV is neither associated with sensorineural hearing loss (SNHL), except for age-related hearing loss (ARHL), nor any other neurological dysfunction that causes balance disorders [
1]. Originally, IBV was found to exhibit bilateral dysfunction in the lateral semicircular canals (LSCCs) and the superior vestibular nerve (SVN) system, as shown by caloric and rotation tests [
1]. Later, the development of vestibular function tests such as the vestibular evoked myogenic potential (VEMP) test [
6‐
9] and the video head impulse test (vHIT) [
10] enabled more detailed assessments of the function of the otolith organs and vertical SCCs (VSCCs). Consequently, it was found that IBV could involve peripheral vestibular lesions other than those of the LSCC and the SVN system [
5,
11‐
17]. Furthermore, novel subtypes of IBV that do not indicate bilateral dysfunction of the LSCC and/or the SVN system have also been proposed [
11,
13‐
16].