Registro del reflejo vestibulooculomotor con la técnica de la bobina corneal en campo magnético (scleral search coil). Revisión de afecciones vestibulares periféricas / Vestibulo-oculomotor reflex recording using the scleral search coil technique. Review of peripheral vestibular disorders

Se revisa la contribución del empleo de la técnica de la bobina escleral en campo magnético (BECM) o scleral search coil (SSC) en diversas afecciones vestibulares periféricas: enfermedad de Ménière, neuritis vestibular, vértigo posicional paroxístico benigno, síndrome de dehiscencia del conducto semicircular superior y neurinoma vestibular. Los movimientos cefálicos detectados por los receptores vestibulares desencadenan el reflejo vestibulooculomotor (RVO) que genera movimientos oculares compensatorios tridimensionales. Por tanto, para el estudio del RVO es necesario valorar la dirección y la velocidad de los movimientos cefálicos y oculares reflejos en tres dimensiones. La técnica de la BECM se basa en que la interacción de un campo magnético con una bobina escleral genera señales eléctricas en ésta que traducen las posiciones ocular y cefálica. El eje de rotación ocular está alineado con el eje de rotación cefálica y la ganancia del RVO (velocidad ocular/velocidad cefálica) en movimientos horizontales y verticales es casi 1, pero en los torsionales es menor (alrededor de 0,7)

Our goal is to review vestibulo-oculomotor reflex (VOR) studies on several peripheral vestibular disorders (Ménière's disease, vestibular neuritis, benign paroxysmal positional vertigo, superior canal dehiscence syndrome, and vestibular neuroma), using the scleral search coil (SSC) technique. Head movements are detected by vestibular receptors and the elicited VOR is responsible for compensatory 3 dimensional eye movements. Therefore, to study the VOR it is necessary to assess the direction and velocity of 3 dimensional head and eye movements. This can be achieved using the SCC technique. Interaction between a scleral search coil and an alternating magnetic field generates an electrical signal that is proportional to eye position. Ideally, eye rotation axis is aligned with head rotation axis and VOR gain (eye velocity/head velocity) for horizontal and vertical head rotations is almost 1. The VOR gain, however, for torsional head rotations is smaller and about 0.7

[Vestibulo-oculomotor reflex recording using the scleral search coil technique. Review of peripheral vestibular disorders]. / Registro del reflejo vestibulooculomotor con la técnica de la bobina corneal en campo magnético (scleral search coil). Revisión de afecciones vestibulares periféricas.

Our goal is to review vestibulo-oculomotor reflex (VOR) studies on several peripheral vestibular disorders (Ménière's disease, vestibular neuritis, benign paroxysmal positional vertigo, superior canal dehiscence syndrome, and vestibular neuroma), using the scleral search coil (SSC) technique. Head movements are detected by vestibular receptors and the elicited VOR is responsible for compensatory 3 dimensional eye movements. Therefore, to study the VOR it is necessary to assess the direction and velocity of 3 dimensional head and eye movements. This can be achieved using the SCC technique. Interaction between a scleral search coil and an alternating magnetic field generates an electrical signal that is proportional to eye position. Ideally, eye rotation axis is aligned with head rotation axis and VOR gain (eye velocity/head velocity) for horizontal and vertical head rotations is almost 1. The VOR gain, however, for torsional head rotations is smaller and about 0.7.

[Vestibular evoked myogenic potentials and benign paroxysmal positional vertigo]. / Resultados de los potenciales evocados miogénicos vestibulares en el vértigo posicional paroxístico benigno.

OBJECTIVE: Benign paroxysmal positional vertigo (BPPV) seems to occur because of otoconia migration into the semicircular canals or their adherence to the cupula. Although the origin of these otoconia lies in the macula of the utricle, vestibular evoked myogenic potentials (VEMPs) can be used assess saccular function. The aim of this study is to assess the saccular function in patients diagnosed with BPPV. PATIENTS AND METHOD: Nineteen patients diagnosed with BPPV of the posterior semicircular canal were included in this study. Their auditory function and their caloric, rotatory chair, and VEMP responses were tested. Ipsilateral and contralateral VEMP thresholds, ipsilateral and contralateral p13 and n23 latencies at 100 dB, inter-peak amplitude and the interaural amplitude difference were determined. RESULTS: We found a lack of VEMP response in 52 % of the ears with BPPV. When adjusted for bilateral absence, VEMP response was absent in 20.3 % of ears. CONCLUSIONS: Some patients with idiopathic BPPV show a degree of saccular dysfunction.

Resultados de los potenciales evocados miogénicos vestibulares en el vértigo posicional paroxístico benigno / Vestibular evoked myogenic potentials and benign paroxysmal positional vertigo

Objetivo: El vértigo posicional paroxístico benigno (VPPB) parece deberse a la migración de otoconias dentro de los conductos semicirculares o su adherencia a la cúpula. Si bien el origen de estas otoconias es la mácula del utrículo, aprovechando que los potenciales evocados miogénicos vestibulares (VEMP) valoran la función del sáculo, nuestro objetivo es estudiar su función en pacientes con VPPB. Pacientes y método: En 19 pacientes con VPPB por afección del conducto semicircular posterior, se valoró el nivel de audición, la respuesta de las pruebas calórica, rotatoria y VEMP. Se determinó en los VEMP ipsolaterales y contralaterales los umbrales, las latencias de las ondas p13 y n23 a 100 dB, la amplitud entre máximos y la diferencia de la amplitud interaural. Resultados: Se halló ausencia de respuesta de los VEMP en el 52 % de los oídos con VPPB. Cuando se corrigió por la ausencia de respuesta bilateral, los VEMP estaban ausentes en el 20,3 % de los casos. Conclusiones: En algunos pacientes con VPPB hay cierto grado de disfunción sacular

Objective: Benign paroxysmal positional vertigo (BPPV) seems to occur because of otoconia migration into the semicircular canals or their adherence to the cupula. Although the origin of these otoconia lies in the macula of the utricle, vestibular evoked myogenic potentials (VEMPs) can be used assess saccular function. The aim of this study is to assess the saccular function in patients diagnosed with BPPV. Patients and method: Nineteen patients diagnosed with BPPV of the posterior semicircular canal were included in this study. Their auditory function and their caloric, rotatory chair, and VEMP responses were tested. Ipsilateral and contralateral VEMP thresholds, ipsilateral and contralateral p13 and n23 latencies at 100 dB, inter-peak amplitude and the interaural amplitude difference were determined. Results: We found a lack of VEMP response in 52 % of the ears with BPPV. When adjusted for bilateral absence, VEMP response was absent in 20.3 % of ears. Conclusions: Some patients with idiopathic BPPV show a degree of saccular dysfunction