[Method of registration of vestibular myogenic evoked potentials in the diagnosis of diseases of the inner ear]. / Metod registratsii vestibulyarnykh miogennykh vyzvannykh potentsialov v diagnostike zabolevanii vnutrennego ukha.

The literature review is devoted to the practical application of the method of recording vestibular evoked myogenic potentials (VEMPs) in the diagnosis of the inner ear diseases: superior semicircular canal dehiscence syndrome, Meniere's disease, benign paroxysmal positional vertigo (BPPV), vestibular neuritis. Registration of VMEP is an electrophysiological research method that allows to assess objectively the functional state of the otolith receptors (sacculus and utriculus) and their pathways, which expands the diagnostic capabilities in diagnosis of the inner ear diseases.

[Vestibular evoked myogenic potentials in patients with recurrent benign paroxysmal positional vertigo]. / Vestibulyarnye vyzvannye miogennye potentsialy u patsientov s retsidiviruyushchim dobrokachestvennym paroksizmal'nym pozitsionnym golovokruzheniem.

Registration of ocular and cervical vestibular evoked myogenic potentials (oVEMPs and cVEMPs) reflects the function of otolith receptors: sacculus and utriculus. Benign paroxysmal positional vertigo (BPPV) is a disease of the inner ear as a result of the utriculus disfunction and migration of otoliths into semicircular channels. OBJECTIVE: To study the function of otolith receptors (sacculus and utriculus) with using VEMPs registration in patients with first-time and recurrent posterior semicircular canal BPPV before and after repositional maneuvers. MATERIAL AND METHODS: Registration and comparison of the results of oVEMPs and cVEMPs were performed in 50 patients with first-time posterior semicircular canal idiopathic BPPV and 26 patients with recurrent posterior semicircular canal BPPV before and after repositional treatment. RESULTS AND DISCUSSION: Clinically significant asymmetry of the amplitude of oVEMPs before treatment was recorded in 14 (38%) of patients with first-time BPPV and in 15 (57.7%) of patients with recurrent BPPV; cVEMPs - in 6 (12%) of patients with first-time BPPV and in 6 (23.1%) of patients with recurrent BPPV. Successful repositional treatment did not affect the amplitude of cVEMPs in any of the groups of patients, but led to a significant increase in the amplitude of oVEMPs on the affected side in patients with first-time BPPV. In patients with recurrent BPPV, despite the absence of symptoms of otolithiasis, the asymmetry of the amplitude of oVEMPs persisted during remission (p<0.05), which can be considered as a prognostically unfavorable factor of disease recurrence.

µVEMP: A Portable Interface to Record Vestibular Evoked Myogenic Potentials (VEMPs) With a Smart Phone or Tablet.

Background: Cervical VEMPs and ocular VEMPs are tests for evaluating otolith function in clinical practice. We developed a simple, portable and affordable device to record VEMP responses on patients, named µVEMP. Our aim was to validate and field test the new µVEMP device. Methods: We recorded cervical VEMPs and ocular VEMPs in response to bone conducted vibration using taps tendon hammer to the forehead (Fz) and to air conducted sounds using clicks. We simultaneously recorded VEMP responses (same subject, same electrode, same stimuli) in three healthy volunteers (2 females, age range: 29-57 years) with the µVEMP device and with a standard research grade commercial (CED) system used in clinics. We also used the µVEMP device to record VEMP responses from six patients (6 females, age mean±SD: 50.3 ± 20.8 years) with classical peripheral audio-vestibular diseases (unilateral vestibular neuritis, unilateral neurectomy, bilateral vestibular loss, unilateral superior canal dehiscence, unilateral otosclerosis). Results: The first part of this paper compared the devices using simultaneous recordings. The average of the concordance correlation coefficient was rc = 0.997 ± 0.003 showing a strong similarity between the measures. VEMP responses recorded with the µVEMP device on patients with audio-vestibular diseases were similar to those typically found in the literature. Conclusions: We developed, validated and field tested a new device to record ocular and cervical VEMPs in response to sound and vibration.This new device is portable (powered by a phone or tablet) with pocket-size dimensions (105 × 66 × 27 mm) and light weight (150 g). Although further studies and normative data are required, our µVEMP device is simpler (easier to use) and potentially more accessible than standard, commercially available equipment.

Vestibular-evoked myogenic potentials in central vestibular disorders.

Vestibular-evoked myogenic potentials (VEMPs) are short latency manifestations of vestibulo-ocular and vestibulocollic reflexes that originate from the utricle and saccule. Although cervical and ocular VEMPs have mostly been applied to peripheral vestibular disorders, the characteristics and the diagnostic values of VEMPs have been expanded to assess the function of the central otolithic pathways. In the central nervous system, the cervical VEMPs (cVEMPs) are mediated by the vestibular nuclei and uncrossed medial vestibulospinal tract descending in the lower brainstem and spinal cord. In contrast, the ocular VEMPs (oVEMPs) reflect the function of the vestibular nuclei and the crossed vestibulo-ocular reflex (VOR) pathways, mostly contained in the medial longitudinal fasciculus (MLF). Therefore, lesions involving the vestibular nuclei can present abnormalities of both cVEMPs and oVEMPs. The medullary lesions involving the descending MLF or the spinal accessory nucleus impair cVEMPs. In contrast, the lesions involving the MLF, the crossed ventral tegmental tract, oculomotor nuclei and the interstitial nucleus of Cajal can impair oVEMPs. Patients with unilateral cerebellar infarctions may show abnormal VEMPs especially when they have the ocular tilt reaction. Delayed responses of VEMPs are characteristic of multiple sclerosis (MS). Reduced VEMP responses can be observed in patients with vestibular migraine. VEMPs are useful in evaluating central as well as peripheral otolithic function that are not readily defined by conventional vestibular function tests, and can aid in detecting and localizing central lesions, especially silent brainstem lesions such as tiny infarctions or MS plaques.

Persistent otolith dysfunction even after successful repositioning in benign paroxysmal positional vertigo.

To evaluate utricular and saccular function during the acute and resolved phases of BPPV, ocular and cervical vestibular evoked myogenic potentials (VEMPs) were studied in 112 patients with BPPV and 50 normal controls in a referral-based University Hospital. Ocular (oVEMPs) and cervical VEMPs (cVEMPs) were induced using air-conducted sound (1000Hz tone burst, 100dB normal hearing level) at the time of initial diagnosis and 2 months after successful repositioning in patients with BPPV, and the results were compared with those of the controls. Abnormalities of cVEMPs and oVEMPs in patients with BPPV were prevalent and significantly higher compare to the healthy control group (p<0.01 in each VEMP by chi-square test). In the patient group, difference between the proportions of abnormal responses of cVEMP and oVEMP was not significant in both affected (p=0.37, chi-squared test) and non-affected (p=1.00) ears. The abnormalities were more likely reduced or absent responses rather than delayed ones; reduced or absent responses are 17.6% in cVEMPs (p=0.04, chi-square) and 21.6% in oVEMPs (p<0.01). The non-affected ear in the BPPV group also showed significantly higher abnormalities of cVEMP and oVEMP when compared to the control group. The follow-up VEMPs after repositioning maneuvers were not significantly different compared to the initial values from both stimulated affected and non-affected ears. Although most patients had unilateral BPPV, bilateral otolithic dysfunction was often shown by persistently reduced or absent cervical and ocular VEMPs, suggesting that BPPV may be caused by significant bilateral damage to the otolith organs.