Novel subtype of idiopathic bilateral vestibulopathy: bilateral absence of vestibular evoked myogenic potentials in the presence of normal caloric responses

Abstract

To characterize clinical features of those patients who showed an absence of vestibular evoked myogenic potential (VEMP) responses in the presence of normal caloric responses bilaterally, we reviewed clinical records of 1,887 consecutive outpatients who complained of balance problems, and identified three patients, who showed absent VEMPs in the presence of normal caloric responses bilaterally with unknown causes. All three patients had episodes of recurrent vertigo without spontaneous, gaze-evoked, or positional nystagmus at the time of examination. They complained of oscillopsia while moving their body or head and showed positive Romberg's signs. Drawing on these cases, we underscore the importance of examining the function of the inferior vestibular nerve system, even with no nystagmus and normal caloric findings, in patients complaining of dizziness or oscillopsia during locomotion.

Power Spectral Analysis of Postural Sway During Foam Posturography in Patients With Peripheral Vestibular Dysfunction

“…Caloric nystagmus was recorded using an electronystagmograph. An abnormal caloric response was defined by either of the following criteria: 1) CP percentage 920% (18); or 2) maximum slow phase eye velocity G10-/s bilaterally (19). A total of 99 consecutive patients showed abnormal caloric responses.…”

Effect of severity of vestibular dysfunction on postural instability in idiopathic bilateral vestibulopathy

“…The main clinical symptom is that of persistent imbalance, particularly in darkness [1]. IBV is not accompanied by hearing loss (except for presbycusis), or any other neurological dysfunction [1,3,4].…”

Bilateral Vestibular Hypofunction: Challenges in Establishing the Diagnosis in Adults

“…Some studies use VEMPs in the evaluation of BVH; however, the application of VEMPs is often not optimal, making it difficult to interpret the results. Two papers described patients with absent cVEMPs and normal caloric responses, demonstrating a new subtype of idiopathic bilateral vestibulopathy called ‘dissociated bilateral vestibulopathy' [11,80]. However, some patients were older than 70 years, in which case age could also be a very likely (physiological) explanation for the absent responses.…”

“…Regarding criteria for BVH, different ones can be used which could probably complement each other. Three examples extracted from the literature are shown in table 2 [7,12,80,163]. …”

“…Firstly, each test has its own limitations in terms of sensitivity, specificity, patient acceptance, costs and duration, and there is still no consensus about diagnostic criteria for BVH [7]. Secondly, since BVH probably represents a functionally heterogeneous disorder with different combined or isolated deficits of the vestibular system, different results from laboratory tests can be expected for different types of BVH [18,80,81]. Thirdly, the output parameters of laboratory tests such as the caloric test, rotatory chair tests and (video) head impulse testing [(V)HIT] show a considerable overlap between patients and healthy subjects [82].…”