Aplicações dos potenciais evocados miogênicos vestibulares: revisão sistemática de literatura / Applications of vestibular-evoked myogenic potentials: a systematic literature review

RESUMO Objetivos Revisar a literatura científica sobre as principais técnicas usadas para gerar o potencial evocado miogênico vestibular (VEMP) e suas aplicações clínicas. Estratégia de pesquisa Os artigos que descrevem os métodos de registro e as aplicações do VEMP foram localizados nas bases de dados PubMed, Web of Science, MEDLINE, Scopus, LILACS e SciELO. O levantamento realizado limitou-se aos artigos publicados nos idiomas Inglês, Português e Espanhol, entre janeiro de 2012 e maio de 2018. Critérios de seleção Artigos sobre os aspectos técnicos para a realização do VEMP ocular, cervical ou do músculo sóleo, com estimulação auditiva ou galvânica e artigos sobre as aplicações clínicas do VEMP foram incluídos; artigos repetidos nas bases de dados, artigos de revisão de literatura, relato de casos, cartas e editoriais foram excluídos. Resultados A estratégia de busca resultou na seleção de 28 artigos. Os estudos evidenciaram três métodos de registro do VEMP: cervical, ocular e no músculo sóleo. As aplicações clínicas do VEMP incluíram doença de Ménière, neurite vestibular, síndrome da deiscência do canal semicircular superior, doença de Parkinson, lesões centrais isquêmicas e mielopatias motoras. Conclusão Independentemente da técnica de registro, o VEMP mostrou-se útil como ferramenta complementar para o diagnóstico de doenças vestibulares periféricas e centrais.

ABSTRACT Purpose To review the scientific literature on the main techniques used to generate vestibular-evoked myogenic potential (VEMP) and its clinical applications. Research strategy A search for articles describing VEMP recording methods and applications was conducted in the PubMed, Web of Science, MEDLINE, Scopus, LILACS and SciELO databases. The search was limited to articles published in English, Portuguese, and Spanish between January 2012 and May 2018. Selection criteria Articles addressing the technical aspects for performing ocular, cervical or soleus VEMP with auditory or galvanic stimulation and articles on the clinical applications of VEMP were included in this review, whereas articles repeated in the databases, literature reviews, case reports, letters, and editorials were excluded. Results The search strategy resulted in the selection of 28 articles. The studies evidenced three methods of VEMP recording: responses from the cervical, ocular and soleus muscle. Clinical applications of VEMP included Meniere's disease, vestibular neuritis, superior semicircular canal dehiscence syndrome, Parkinson's disease, central ischemic lesions, and motor myelopathies. Conclusion Regardless of the recording technique, VEMP has proved to be useful as a complementary tool for the diagnosis of peripheral and central vestibular diseases.

Effect of virtual reality in Parkinson's disease: a prospective observational study / Efeito da realidade virtual na doença de Parkinson: estudo observacional prospectivo

ABSTRACT Objective: To assess the effectiveness of balance exercises by means of virtual reality games in Parkinson's disease. Methods: Sixteen patients were submitted to anamnesis, otorhinolaryngological and vestibular examinations, as well as the Dizziness Handicap Inventory, Berg Balance Scale, SF-36 questionnaire, and the SRT, applied before and after rehabilitation with virtual reality games. Results: Final scoring for the Dizziness Handicap Inventory and Berg Balance Scale was better after rehabilitation. The SRT showed a significant result after rehabilitation. The SF-36 showed a significant change in the functional capacity for the Tightrope Walk and Ski Slalom virtual reality games (p < 0.05), as well as in the mental health aspect of the Ski Slalom game (p < 0.05). The Dizziness Handicap Inventory and Berg Balance Scale showed significant changes in the Ski Slalom game (p < 0.05). There was evidence of clinical improvement in patients in the final assessment after virtual rehabilitation. Conclusion: The Tightrope Walk and Ski Slalom virtual games were shown to be the most effective for this population.

RESUMO Objetivo: Verificar a eficácia dos exercícios de equilíbrio com realidade virtual (RVi) na doença de Parkinson. Métodos: Dezesseis pacientes foram submetidos a uma anamnese, exames otorrinolaringológico e vestibular, ao Dizziness Handicap Inventory (DHI), Escala de Equilíbrio de Berg (EEB), questionário SF-36 e o Teste de Sentar e Levantar (TSL) que foram aplicados antes e após a reabilitação com RVi. Resultados: Os resultados dos escores finais do DHI e EEB foram melhores após a reabilitação. O TSL apresentou resultado significativo após a reabilitação. O SF-36 demonstrou alteração significativa da capacidade funcional para os jogos Tightrope Walk e Ski Slalom (p < 0,05) e da saúde mental para o jogo Ski Slalom (p < 0,05). O DHI e EEB apresentaram alterações significativas no jogo Ski Slalom (p < 0,05). Houve melhora clínica evidente dos pacientes após reabilitação virtual. Conclusão: Os jogos virtuais Tightrope Walk e o Ski Slalom foram os mais eficazes.

The Linear Transmission of the Vestibular Neural Information by Galvanic Vestibular Stimulation / 대한평형의학회지

OBJECTIVE: Growing hypotheses indicate the galvanic vestibular stimulation (GVS) as an alternative method to manage the symptoms of parkinson's disease (PD). GVS is easy and safe for use, and non-invasive. However, it is elusive how the neural information caused by GVS is transmitted in the central nervous system and relieves PD symptoms. To answer this question, we investigated the transmission of neural information by GVS in the central vestibular system, focused on vestibular nucleus (VN). METHODS: Twenty guinea pigs were used for this study for the extracellular neuronal recordings in the VN. The neuronal responses to rotation and GVS were analyzed by curve-fitting, and the numerical responding features, amplitudes and baselines, were computed. The effects of stimuli were examined by comparing these features. RESULTS: Twenty six vestibular neurons (15 regular and 11 irregular neurons) were recorded. Comparing the difference of baselines, we found the neural information was linearly transmitted with a reduced sensitivity (0.75). The linearity in the neural transmission was stronger in the neuronal groups with regular (correlation coefficient [Cor. Coef.]=0.91) and low sensitive units (Cor. Coef.=0.93), compared with those with irregular (Cor. Coef.=0.86) and high-sensitive neurons (Cor. Coef.=0.77). CONCLUSION: The neural information by GVS was linearly transmitted no matter what the neuronal characteristics were.

Immunohistochemical Study on beta1- and beta2-Adrenergic Receptors in Rat Vestibular Nuclei / 대한평형의학회지

BACKGROUND AND OBJECTIVES: The aim of this study was to examine the localizations of beta1- and beta2-adrenergic receptors (ARs) in rat vestibular nuclei by immunohistochemical staining procedure. MATERIALS AND METHODS: Twelve male Sprague-Dawley rats were used in this study. Primary antibodies for the beta1- and beta2-ARs were used. The sections were treated with a biotinylated goat anti-rabbit antibody. The sections were then incubated in avidin-biotin-peroxidase reagent and processed with immunoperoxidase using 3.3'-diaminobenzidine tetrahydrochloride. RESULTS: beta1-AR and beta2-AR immunopositive neurons were found to be distributed throughout the four major vestibular nuclei. Both receptors were primarily detected in neuronal somata and their proximal dendrites. beta1-AR and beta2-AR were moderately expressed in the superior vestibular nucleus, lateral vestibular nucleus, medial vestibular nucleus, and spinal vestibular nucleus. CONCLUSION: The present study demonstrates, for the first time, that beta1-AR and beta2-AR receptors are localized in rat vestibular nuclei. Furthermore, this study may provide additional speculation into the role of ARs during vestibular signal processing. Further studies are needed to clarify the roles played by beta1-ARs and beta2-ARs through physiologic and functional studies.

Temporal Changes of the Calcium-binding Proteins in the Medial Vestibular Nucleus following Unilateral Labyrinthectomy in Rats

Calcium (Ca2+) is an intracellular second messenger associated with neuronal plasticity of the central nervous system. The calcium-binding proteins regulate the Ca2+-mediated signals in the cytoplasm and buffer the calcium concentration. This study examined temporal changes of three calcium-binding proteins (calretinin, calbindin and parvalbumin) in the medial vestibular nucleus (MVN) during vestibular compensation after unilateral labyrinthectomy (UL) in rats. Rats underwent UL, and the changes in the expression of these proteins at 2, 6, 12, 24, 48, and 72 h were examined by immunofluorescence staining. The expression levels of all three proteins increased immediately after UL and returned to the control level by 48 h. However, the level of calretinin showed changes different from the other two proteins, being expressed at significantly higher level in the contralateral MVN than in the ipsilateral MVN 2 h after UL, whereas the other two proteins showed similar expression levels in both the ipsilateral and contralateral MVN. These results suggest that the calcium binding proteins have some protective activity against the increased Ca2+ levels in the MVN. In particular, calretinin might be more responsive to neuronal activity than calbindin or parvalbumin.

Expression of Glutamate Receptors in the Medial Vestibular Nuclei following Acute Hypotension

Acute hypotension induced excitation of electrical activities and expression of c-Fos protein and pERK in the vestibular nuclei. In this study, to investigate the excitatory signaling pathway in the vestibular nuclei following acute hypotension, expression of NR2A and NR2B subunits of glutamate NMDA receptor and GluR1 subunit of glutamate AMPA receptor was determined by RT-PCR and Western blotting in the medial vestibular nucleus 30 min after acute hypotension in rats. Acute hypotension increased expression of NR2A, NR2B, and pGluR1 in the medial vestibular nuclei. These results suggest that both of NMDA and AMPA glutamate receptors take part in transmission of excitatory afferent signals following acute hypotension.

Effects of 5-Hydroxytryptamine on Potassium Currents of the Medial Vestibular Nuclear Neuron in the Rat / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: This study was aimed to explore the effects of the 5-hydroxytryptamine (5-HT) on potassium currents in rat vestibular nuclear neurons. MATERIALS AND METHOD: Sprague-Dawley rats aged 14 to 16 days were anesthetized with ether and decapitated. After enzymatic digestion, the portion of medial vestibular nucleus neuron was removed by micropunching and gently agitated. The dissociated neurons were transferred into a recording chamber mounted on an inverted microscope and whole-cell membrane currents were recorded at room temperature by using standard patch-clamp techniques. RESULTS: When cells were held at -70 mV and depolarized from -60 mV to +40 mV in 10 mV increments, sustained outward potassium currents were evoked. The response of medial vestibular nuclear neurons to 5-HT was not uniform. The outward potassium currents were increased in 17 of 40 cells and decreased in 23 of 40 cells. 5-carboxamidotryptamine, 5-HT1 agonist increased the outward potassium currents of the medial vestibular nuclear cell. alpha-methyl-5-hydroxytryptamine, 5-HT2 agonist decreased the outward potassium currents of the medial vestibular nuclear cell. CONCLUSION: These results suggest that 5-HT affects the potassium currents of the cell with different effects according to the receptor subtype on which it acts.

The Role of the Vestibular System in Modulating Blood Pressure of Sinoaortic Denervated Rats

BACKGROUND AND OBJECTIVES: The vestibuloautonomic reflex controls respiration and blood pressure during locomotion. The purpose of this study was to investigate the role of the peripheral vestibular receptor in the control of blood pressure in sinoaortic denervated (SAD) rats. MATERIALS AND METHODS: The baroreceptor reflex was removed by SAD in labyrinthectomized rats. The expression of c-Fos protein in the vestibular nuclear complex, and other nuclei related to control of blood pressure, was measured following the induction of acute hypotension using sodium nitroprusside (SNP). RESULTS: The SNP induced acute hypotension, in intact labyrinthine rats, increased the expression of c-Fos protein in the supraoptic nucleus, paraventricular nucleus, rostral ventrolateral medulla, solitary nucleus, and vestibular nuclear complex. The expression of c-Fos protein, following the SNP induced acute hypotension in the SAD rats, increased the expression of c-Fos protein in the paraventricular nucleus, rostral ventrolateral medulla, and medial and inferior vestibular nuclei. The acute hypotension induced by SNP in a unilateral labyrinthectomy, with SAD, increased the expression of c-Fos protein in the contralesional vestibular nuclear complex, but decreased its expression in the ipsilesional vestibular nuclear complex. The acute hypotension induced by SNP in a bilateral labyrinthectomy, with SAD, showed only slight expression of c-Fos protein in the bilateral vestibular nuclear complex. CONCLUSION: These results suggest that the acute hypotension induced by SNP activates the vestibular nuclear neurons by decreasing the blood flow in the peripheral vestibular receptors, and that these in turn modulate blood pressure through activation of the catecholaminergic nervous system and neuroendocrine reflex.

Effect of Ginkgo biloba on Expression of c-Fos Protein in the Vestibular Nuclear Complex following Unilateral Labyrinthectomy in Rats

BACKGROUND AND OBJECTIVES: The neuroprotective effect of Ginkgo biloba has been demonstrated in several in vivo and in vitro models. The effect of Ginkgo biloba on vestibular compensation following unilateral labyrinthectomy (UL) was investigated. Material and Methods: Spontaneous nystagmus and c-Fos protein expression were measured following UL in Sprague-Dawley rats with pretreatment of Ginkgo biloba (50 mg/kg, i.p.). RESULTS: After pretreatment with Ginkgo biloba (50 mg/kg, i.p.) expression of c-Fos protein in the vestibular nuclear complex and frequency of spontaneous nystagmus were measured till 24 hours after UL. UL produced spontaneous nystagmus with frequency of 124+/-.2 beats/min at post-op 2 hrs and 70+/-.1 beats/min at post-op 24 hrs. Pretreatment with Ginkgo biloba significantly decreased the frequency of spontaneous nystagmus till post-op 24 hrs compared to control group (p<0.05). UL produced marked expression of c-Fos protein in bilateral medial vestibular nucleus, inferior vestibular nucleus, and superior vestibular nucleus, and the number of expression was significantly higher in contralateral vestibular nuclei to the lesion than ipsilateral vestibular nuclei at post-op 2 hrs (p<0.01). The number of c-Fos protein expression was decreased with time and significantly higher in ipsilateral vestibular nuclei than contralateral ones at post-op 24 hrs (p<0.01). Pretreatment with Ginkgo biloba significantly decreased the number of c-Fos protein expression following UL (p<0.01) and abolished the asymmetry of c-Fos protein expression in bilateral vestibular nuclei at post-op 24 hrs. CONCLUSION: These results suggest that Ginkgo biloba may facilitate vestibular compensation following UL through modulation of neurotransmitters and neuroprotective effects.

Expression of Fos Protein in Brainstem Vestibular Nuclei of Rat-II. Sinusoidal Acceleration Stimulation- / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Fos, the protein product of c-fos gene, has been known to be rapidly expressed in neurons following various external and internal stimuli and this protein expression has been used as a neural activation marker in many fields. This experiment was performed to examine the afferent pathway of the lateral semicircular canals following sinusoidal acceleration. MATERIALS & METHODS: To stimulate the lateral semicircular canals, animals received rotary stimulation for 90 minutes with 2.0Hz sinusoidal acceleration. Thirty minutes after stimulation, the subjects were sacrificed and their brainstems were processed for immunohistochemistry to detect Fos expression. RESULTS: Fos proteins were strongly expressed in the superior, dorsal medial vestibular and inferior vestibular nuclei. However, there was no expression in the lateral and ventral portion of medial vestibular nuclei. CONCLUSION: This finding suggested that the afferent pathway from peripheral vestibular end-organ can be successfully mapped by detection of Fos expression and Fos is an useful neural activity marker in the vestibular system.

c-fos Expression in Medial Vestibular Nucleus of Guinea Pigs After Unilateral Labyrinthectomy / 听力学及言语疾病杂志

Objective To investigate the c-fos ex pr ession in guinea pigs' medial vestibular neuleus (MVN) following unilateral laby rinthectomy (UL). Methods Twenty-seven SCO guinea pigs were randomly divide d into nine groups, three in each group. After resection of right labyrinth,th e immunohistological staining of c-fos was performed. Fos-like immunoreactivity (FLI) was analyzed at fifteen minutes, and 1?2?6?8?12 and 24 h, and 2 and 7 days after UL. Results Results showed no Fos expression in the control g roup. By contrast, Fos was consistently induced in the UL guinea pigs. Asymmetri cal labeling was found in the bilateral medial vestibular nucleus, with more Fos -like neurons in the ipsilateral MVN of the lesioned side than that in the contr alateral MVN(P

Effects of electrical stimulation of the vestibular system on neuronal activity of the ipsilateral medial vestibular nuclei following unilateral labyrinthectomy in rats

The purpose of this study was to evaluate the effects of electrical stimulation on vestibular compensation following ULX in rats. Electrical stimulation (ES) with square pulse (100 ~ 300 uA, 1.0 ms, 100 Hz) was applied to ampullary portion bilaterally for 6 and 24 hours in rats receiving ULX. After ES, animals that showed the recovery of vestibular symptoms by counting and comparing the number of spontaneous nystagmus were selected for recording resting activity of type I, II neurons in the medial vestibular nuclei (MVN) of the lesioned side. And then the dynamic neuronal activities were recorded during sinusoidal rotation at a frequency of 0.1 Hz and 0.2 Hz. The number of spontaneous nystagmus was significantly different 24 hours (p< 0.01, n = 10), but not 6 hours after ULX+ES. As reported by others, the great reduction of resting activity only in the type I neurons ipsilateral to lesioned side was observed 6, 24 hours after ULX compared to that of intact labyrinthine animal. However, the significant elevation (p < 0.01) of type I and reduction (p < 0.01) of type II neuronal activity were seen 24 hours after ULX+ES. Interestingly, gain, expressed as maximum neuronal activity(spikes/sec)/maximum rotational velocity (deg/sec), was increased in type I cells and decreased in type II cells 24 hours after ULX+ES in response to sinusoidal rotation at frequencies of both 0.1 Hz and 0.2 Hz. This result suggests that accompanying the behavioral recovery, the electrical stimulation after ULX has beneficial effects on vestibular compensation, especially static symptoms (spontaneous nystagmus), by enhancing resting activity of type I neurons and reducing that of type II neurons.

Correlation between electrical activity of type I neuron and c-Fos expression in the medial vestibular nuclei following unilateral labyrinthectomy in rats

To search the correlations between electrical activity and c-Fos expression in the process of vestibular compensation, we examined the changes of those two parameters in the medial vestibular nuclei (MVN) of unilaterally labyrinthectomized (ULX) rats. Spontaneous nystagmus with fast component toward the intact side disappeared gradually within 48 hours. Fourty eight hours after ULX, directional preponderance of the eye movement induced by sinusoidal rotation of the whole body which represents the symmetry of bilateral vestibular functions showed less than 20% by rotation of 0.1, 0.2, and 0.5 Hz, indicating the recovery of symmetry in bilateral vestibular functions. Six hours after ULX, spontaneous electrical activity of type I neurons resulted in asymmetry between bilateral MVN, however, the asymmetry of the electrical activity was decreased 48 hours after ULX. Immunocytochemical staining revealed that ULX produced dramatic induction of c-Fos positive cells in the MVN bilaterally. The number of c-Fos immunoreactive cells in the contralateral MVN was significantly higher than those in the ipsilateral MVN (p<0.0001) 2 hours after ULX. Thereafter, the number of c-Fos positive cells decreased bilaterally and was slightly, but not significantly higher in the ipsilateral MVN at 48 hours after ULX. The present results suggest that both electrical activity of type I neurons and c-Fos expression in MVN following ULX will reflect underlying mechanisms of recovery process of vestibular compensation.

Expression of Fos Protein in Brainstem Vestibular Nuclei of Rat - I. Off-axis Centripetal Acceleration - / 대한이비인후과학회지

Fos, the protein product of c-fos gene, has been known to be rapidly expressed in neurons following various external and internal stimuli. This experiment was performed to determine whether off-axis centripetal acceleration cause a proper stimulation to the otolith organ and the afferent neural pathway from the otolith organ can be mapped by detection of expressed Fos protein. Therefore we performed on-axis and off-axis centripetal acceleration stimulation to experimental animals and investigated Fos expression immunohistochemically. In results, there were no expression of Fos protein following on-axis centripetal acceleration, whereas in the medial, descending vestibular nuclei and y-group of the off-axially stimulated animal, we could find strong expression of Fos protein.