International classification of bilateral vestibulopathy (BVP)
Reviewed by Victor Osei-Lah

In the past few years the Bárány Society have been standardising the diagnostic criteria for various vestibular disorders – International Classification of Vestibular Disorders (ICVD). Diagnosis of BVP relies on history, bedside clinical assessment and objective vestibular tests. The authors claim the criteria are such that they are practical and can be applied globally, bearing in mind the availability of objective testing is not the same everywhere. There are two categories of BVP each characterised by features labelled A – D, A and B describing the symptoms, C, findings on examination and testing and D, not better accounted for by another disease. The criteria for BVP are: A - unsteadiness when walking or standing plus at least one of worsening unsteadiness in the dark and/or uneven ground, or oscillopsia during walking and head/body movement; B – no symptoms sitting or lying under static conditions; C – bilaterally absent or reduced angular VOR function documented by bilateral horizontal video-HIT VOR gain of <0.6, and/or reduced bilateral bithermal caloric maximum SPV <6⁰/sec, and/or reduced horizontal angular VOR gain of <0.1 on sinusoidal rotation and a phase lead >68⁰. The criteria for probable BVP are: A and B – same as BVP; C – bilaterally pathological horizontal bedside head impulse test. The authors provide information on epidemiology, aetiology and differential diagnoses. They gave reasons for not including, what they described as complementary tests, dynamic visual acuity (DVA), Romberg test and VEMPs (c- and o). For DVA, they argued that it can “help to establish the diagnosis of BVP, but a normal DVA does not definitely rule out BVP, and an impaired DVA does not imply vestibular hypofunction per se; it is still not understood by which specific vestibular deficits (which semicircular canal, which otolith organs and which frequencies) DVA decreases.” The limitations of VEMPs are discussed. I thought we had moved away from solely relying on horizontal semicircular canal (HSSC) pathology in the diagnosis of BVP but the criteria are heavily reliant on HSSC function. This is disappointing in light of recent advances in vestibulometry. Secondly, one could only diagnose probable BPV if there is no access to v-HIT. However, this is a good start. I hope it is revised sooner than later. 

Bilateral vestibulopathy: diagnostic criteria consensus document of the classification committee of the Bárány Society.
Strupp M, Kim J-S, Murofushi T, et al.
JOURNAL OF VESTIBULAR RESEARCH
2017;27:177-89.