RESUMO
OBJECTIVES: To evaluate pre- and post-operative semicircular canal function in patients with vestibular schwannoma (VS) by the video Head Impulse Test (vHIT). METHODS: Nineteen patients with VS who underwent surgery were enrolled in this study. The gain in vestibulo-ocular reflex (VOR) and the degree of scatter in catch-up saccades were examined pre- and post-operatively for the semicircular canals in VS patients. RESULTS: Ten of 19 cases (52.6 %) with VS were defined as demonstrating both superior vestibular nerve (SVN) and inferior vestibular nerve (IVN) impairment from the results of pre-operative vHIT. Hearing level and subjective vestibular symptoms showed significant correlations with pre-operative semicircular canal function. Compared to pre-operative vHIT results, VOR gains within 1 month after surgery were significantly reduced in all three canals; however, significant differences had disappeared in the anterior and posterior semicircular canals at 6 months after surgery. Cases of unknown origin had a significantly greater reduction in posterior semicircular canal function after surgery compared with those with disease of IVN origin. CONCLUSIONS: As vHIT could evaluate pre-operative vestibular nerve impairment, post-operative VOR gain reduction and the degree of vestibular compensation, semicircular canal function evaluated by vHIT provides a good deal of useful information regarding VS patients undergoing surgery compared to caloric testing, and vHIT should be performed pre- and post-operatively for patients with VS.
Assuntos
Teste do Impulso da Cabeça , Neuroma Acústico , Reflexo Vestíbulo-Ocular , Canais Semicirculares , Humanos , Neuroma Acústico/cirurgia , Neuroma Acústico/fisiopatologia , Canais Semicirculares/fisiopatologia , Feminino , Pessoa de Meia-Idade , Masculino , Reflexo Vestíbulo-Ocular/fisiologia , Adulto , Idoso , Gravação em Vídeo , Movimentos Sacádicos/fisiologia , Período Pós-Operatório , Nervo Vestibular/fisiopatologiaRESUMO
Although symptoms of unilateral vestibular neuritis (uVN) resolve spontaneously within several weeks, recovery of gait function has unclearness in gait parameter changes and mediolateral stability improvements. In addition, prospective longitudinal studies on gait parameters after uVN are lacking. This study was conducted to reveal longitudinal change of gait function after acute uVN and to help the precise rehabilitation planning. Twenty three participants with uVN and 20 controls were included. 3D gait analyses were conducted three times after uVN onset at monthly intervals. From the gait analysis data, spatio-temporal parameters, inclination angle (IA) representing the relationship between center of mass (CoM) and center of pressure (CoP) in the frontal plane, and IA variability were obtained. Time effects on gait metrics were tested. Walking speed of participants with uVN improved significantly between the 1st and 3rd tests, but they were not significantly different to that of control, even in the 1st test. The step width of participants with uVN was significantly larger than that of control in the 1st test and improved significantly in the 2nd test. Variability of IA in affected side was significantly larger than that in controls in the 1st test and improved significantly in the 3rd test compared to the 1st test. Improvement of overall gait function and mediolateral stability during gait continued after acute stage of uVN (two months from onset in this study). Rehabilitation intervention should be continued after the acute stage of uVN to enhance appropriate adaptation in gait.
Assuntos
Marcha/fisiologia , Equilíbrio Postural , Nervo Vestibular/fisiopatologia , Neuronite Vestibular/fisiopatologia , Velocidade de Caminhada , Adaptação Fisiológica , Adulto , Idoso , Feminino , Lateralidade Funcional , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Percepção , Estudos Prospectivos , Reprodutibilidade dos Testes , CaminhadaRESUMO
Exposure to 120 dB sound pressure level (SPL) band-limited noise results in delayed onset latency and reduced vestibular short-latency evoked potential (VsEP) responses. These changes are still present 4 wk after noise overstimulation. Noise-induced hearing loss (NIHL) has been shown to vary in extent and duration based on the noise intensity. This study investigated whether noise-induced peripheral vestibular hypofunction (NPVH) would also decrease in extent and/or duration with less intense noise exposure. In the present study, rats were exposed to a less intense noise (110 dB SPL) but for the same duration (6 h) and frequency range (500-4,000 Hz) as used in previous studies. The VsEP was assessed 1, 3, 7, 14, 21, and 28 days after noise exposure. In contrast to 120 dB SPL noise exposure, the 110 dB SPL noise exposures produced smaller deficits in VsEP responses that fully recovered in 62% (13/21) of animals within 1 wk. These findings suggest that NPVH, a loss or attenuation of VsEP responses with a requirement for elevated stimulus intensity to elicit measurable responses, is similar to NIHL, that is, lower sound levels produce a smaller or transient deficit. These results show that it will be important to determine the extent and duration of vestibular hypofunction for different noise exposure conditions and their impact on balance.NEW & NOTEWORTHY This is the first study to show a temporary noise-induced peripheral vestibular hypofunction that recovers following exposure to continuous noise.
Assuntos
Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Ruído/efeitos adversos , Doenças Vestibulares/etiologia , Doenças Vestibulares/fisiopatologia , Potenciais Evocados Miogênicos Vestibulares/fisiologia , Nervo Vestibular/fisiopatologia , Doenças do Nervo Vestibulococlear/etiologia , Doenças do Nervo Vestibulococlear/fisiopatologia , Estimulação Acústica , Animais , Modelos Animais de Doenças , Perda Auditiva Provocada por Ruído , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND: High-resolution MR imaging enables the visualization of individual nerves in the internal auditory canal (IAC). Cochlear nerve deficiency (CND) is recognized as one of the major causes of sensory neural hearing loss (SNHL), especially in cases of unilateral hearing loss in childhood. Some patients with CND are thought to have accompanying vestibular nerve deficiency (VND). However, there have been few reports focusing on VND and vestibular function in these children. AIMS: The aim of this study was to evaluate the frequency of VND and vestibular dysfunction in children with unilateral SNHL caused by CND. MATERIAL AND METHODS: Thirty-eight children with unilateral SNHL, who were diagnosed with CND by 3 T-MRI, were evaluated for VND and underwent caloric testing and cervical vestibular evoked potential (cVEMP). RESULTS: Fourteen of 38 patients (37%) had VND, and eleven (29%) of the patients [ten of the patients (71%) with VND] had at least one vestibular dysfunction. The patients with VND had significantly worse hearing and an IAC of smaller diameter than did patients without VND. CONCLUSIONS AND SIGNIFICANCE: We should pay attention to VND as well as vestibular dysfunction in hearing loss patients with CND.
Assuntos
Nervo Coclear/fisiopatologia , Perda Auditiva Unilateral/fisiopatologia , Nervo Vestibular/fisiopatologia , Doenças do Nervo Vestibulococlear/complicações , Adolescente , Criança , Nervo Coclear/diagnóstico por imagem , Feminino , Perda Auditiva Neurossensorial/etiologia , Perda Auditiva Unilateral/etiologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Nervo Vestibular/diagnóstico por imagemRESUMO
BACKGROUND: Vestibulo-ocular reflex (VOR) function is expected to be normal in patients with presbycusis during sudden head rotations. AIM: This study aimed to determine whether presbycusis was accompanied by vestibular system pathologies. In addition, it was examined whether there was a difference existed between the patients with and without presbycusis in terms of normative data. MATERIALS AND METHODS: A total of 40 individuals were included in the study: 20 in the presbycusis group and 20 in the control group. The vestibular systems of both groups were evaluated using the video head impulse test and videonystagmography. RESULTS: The right and left lateral VOR gain values were decreased in the group with presbycusis compared to the control group. The difference between the two groups in the mean VOR gains in the right lateral canal and left lateral canal were statistically significant (p = .040 and p = .050, respectively). The air caloric tests of all individuals were found to be normal. CONCLUSIONS: This result suggests that the loss of vestibular hair cells and vestibular nerve degeneration in the lateral semicircular canal may be more severe in presbycusis than in the same age group with normal hearing.
Assuntos
Células Ciliadas Vestibulares/patologia , Presbiacusia/fisiopatologia , Reflexo Vestíbulo-Ocular , Canais Semicirculares/fisiologia , Doenças Vestibulares/complicações , Nervo Vestibular/fisiologia , Idoso , Estudos de Casos e Controles , Feminino , Teste do Impulso da Cabeça , Humanos , Masculino , Pessoa de Meia-Idade , Nistagmo Patológico/complicações , Presbiacusia/complicações , Presbiacusia/patologia , Testes de Função Vestibular , Nervo Vestibular/fisiopatologia , Vestíbulo do LabirintoRESUMO
The vestibular system is vital for maintaining balance and stabilizing gaze and vestibular damage causes impaired postural and gaze control. Here we examined the effects of vestibular loss and subsequent compensation on head motion kinematics during voluntary behavior. Head movements were measured in vestibular schwannoma patients before, and then 6 weeks and 6 months after surgical tumor removal, requiring sectioning of the involved vestibular nerve (vestibular neurectomy). Head movements were recorded in six dimensions using a small head-mounted sensor while patients performed the Functional Gait Assessment (FGA). Kinematic measures differed between patients (at all three time points) and normal subjects on several challenging FGA tasks, indicating that vestibular damage (caused by the tumor or neurectomy) alters head movements in a manner that is not normalized by central compensation. Kinematics measured at different time points relative to vestibular neurectomy differed substantially between pre-operative and 6-week post-operative states but changed little between 6-week and > 6-month post-operative states, demonstrating that compensation affecting head kinematics is relatively rapid. Our results indicate that quantifying head kinematics during self-generated gait tasks provides valuable information about vestibular damage and compensation, suggesting that early changes in patient head motion strategy may be maladaptive for long-term vestibular compensation.
Assuntos
Denervação/efeitos adversos , Cabeça/fisiologia , Movimento , Neuroma Acústico/fisiopatologia , Neuroma Acústico/cirurgia , Procedimentos Cirúrgicos Otológicos/métodos , Neoplasias do Sistema Nervoso Periférico/fisiopatologia , Neoplasias do Sistema Nervoso Periférico/cirurgia , Nervo Vestibular/fisiopatologia , Nervo Vestibular/cirurgia , Vestíbulo do Labirinto/inervação , Doença Aguda , Doença Crônica , Denervação/métodos , Marcha/fisiologia , Humanos , Procedimentos Cirúrgicos Otológicos/efeitos adversos , Equilíbrio Postural/fisiologiaRESUMO
OBJECTIVES: The study aimed at the analysis of the parameters of acoustic cervical and ocular vestibular evoked myogenic potentials (AC-cVEMP and AC-oVEMP) response in patients with a confirmed tumor located in the internal auditory canal. It also aimed to assess to what degree a combination of these tests may be of benefit in the preoperative indication of the affected nerve division via preoperative determination whether the tumor originated from the superior or inferior division of the vestibular nerve, both divisions, or if it originated from a different nerve in the internal auditory canal. METHODS: The study group included 50 patients. Preoperative MRI scans were used to measure tumor diameter. AC-cVEMP and AC-oVEMP testing were performed before tumor resection. The surgeon was asked for a detailed description of the tumor origin. RESULTS: The corrected amplitude of cVEMP was significantly lower on the tumor side than on the non-affected side and in the control group. The corrected Asymmetry Ratio (AR) of cVEMPs in patients with the tumor was significantly elevated above the reference values with the mean being 58.29% and the mean AR of oVEMPs in patients the tumor was 71.78% which made both results significantly higher than in the control group. Neither cVEMP nor oVEMP latency was significantly correlated with tumor size. Data obtained from cVEMP and oVEMP tests was an effective indicator of tumor origin in 74% of patients showing which division (or both divisions) of the VIIIth nerve was affected in comparison with information obtained from the surgeon. CONCLUSIONS: The combined use of AC-cVEMP and AC-oVEMP tests may be useful in surgical planning in patients the tumor located in the internal auditory canal, providing a highly probable determination of the division of the affected nerve. Such information is valuable for the surgeon as it offers additional knowledge about the tumor before the procedure. cVEMP and oVEMP results may not be used as the basis for the calculation of tumor size in patients.
Assuntos
Estimulação Acústica , Nervo Coclear/fisiopatologia , Neoplasias dos Nervos Cranianos/diagnóstico , Potenciais Evocados Miogênicos Vestibulares/fisiologia , Nervo Vestibular/fisiopatologia , Doenças do Nervo Vestibulococlear/diagnóstico , Estudos de Casos e Controles , Neoplasias dos Nervos Cranianos/fisiopatologia , Orelha Interna , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Doenças do Nervo Vestibulococlear/fisiopatologiaRESUMO
INTRODUCTION: Etiology of ISSNHL includes cessation of vascular perfusion, viral infection and cochlear membrane injury. Precise location of injury should be defined for a target-oriented treatment. Vestibular complaints in ISSNHL are hypothesized as involvement of vestibule. Vestibular complaints can be either due to involvement of inner ear or neural tract at any level. OBJECTIVES: In the present study we aimed to demonstrate involvement of vestibular organs in the absence of vestibular symptoms. It was aimed to evaluate superior and inferior vestibular neural pathways. METHODS: c-vemp and o-vemp were applied to patients suffering ISSNHL without vertigo. Pure tone averages, audiogram configurations, degree of hearing loss were analyzed. Latencies of P1 and N1 waves, amplitudes of P1-N1 waves were evaluated. Asymmetrical vemp wave patterns were compared between two ears regarding difference of PTA. RESULTS: Latencies of c-vemp waves were longer and amplitudes were smaller. o-vemp parameters were similar on both sides. Positive correlation was observed between c-vemp latencies and degree hearing loss. CONCLUSION: Inferior vestibular nerve pathway is affected in the absence of vertigo in ISSNHL with spared superior vestibular nerve pathway. Damage in IVN pathway correlates with degree of ISSNHL.
Assuntos
Orelha Interna/patologia , Perda Auditiva Neurossensorial/patologia , Perda Auditiva Súbita/patologia , Potenciais Evocados Miogênicos Vestibulares , Nervo Vestibular/patologia , Vestíbulo do Labirinto/lesões , Adulto , Idoso , Audiometria , Estudos Transversais , Feminino , Perda Auditiva Neurossensorial/fisiopatologia , Perda Auditiva Súbita/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Vertigem , Nervo Vestibular/fisiopatologia , Vestíbulo do Labirinto/inervação , Vestíbulo do Labirinto/patologiaRESUMO
Vestibular schwannomas (VSs) were proposed to arise from the glial-Schwann cell junction within the internal auditory canal (IAC). However, otopathology studies indicate that VS may arise anywhere along the course of the vestibular nerve. Recent studies suggested that the majority of tumors are located centrally within the IAC with an equal distribution near the porus acusticus and the fundus. However, these studies analyzed tumors of all sizes, obscuring their precise origin. Herein, we aim to quantify the position of small intracanalicular tumors (<5 mm), assessing hearing outcomes and growth patterns in relation to tumor position. Of the 38 small intracanalicular tumors analyzed, 61% originated closest to the fundus, 34% at the midpoint, and only 5% closest to the porus acusticus. Tumors were observed with serial magnetic resonance imaging for 3.37 ± 2.65 years (mean ± SD) without intervention. Our findings indicate a lateral predominance of small VS within the IAC, an independence between tumor location and hearing outcomes, and further support the slow natural progression of VS.
Assuntos
Perda Auditiva/diagnóstico , Audição/fisiologia , Imageamento por Ressonância Magnética/métodos , Neuroma Acústico/diagnóstico , Nervo Vestibular/patologia , Idoso , Audiometria de Tons Puros , Feminino , Perda Auditiva/etiologia , Perda Auditiva/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Neuroma Acústico/complicações , Neuroma Acústico/fisiopatologia , Estudos Retrospectivos , Nervo Vestibular/fisiopatologiaRESUMO
We report a case of acute vestibulopathy with the simultaneous involvement of both superior and inferior vestibular nerves on both sides. A 36-year-old female presented with dizziness, oscillopsia and a walking impairment subsequent to a high fever. Vestibular function tests including caloric testing, video head impulse testing (vHIT) and cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) were performed. In the first examination, vHIT and caloric testing showed severe impairments in all three semicircular canals in each ear, and both cVEMPs and oVEMPs were absent on both sides. During a 1-year follow-up, the gain of vHIT gradually recovered by more than 0.5 to normal. cVEMPs also recovered to normal on both sides while oVEMPs remained absent on both sides. This is the first reported case of acute bilateral vestibulopathy with simultaneous involvement of both superior and inferior vestibular nerves on both sides. Repeated evaluation of vestibular function using vHIT, cVEMPs and oVEMPs is helpful to assess the time course of recovery in patients with vestibulopathy.
Assuntos
Vestibulopatia Bilateral/diagnóstico , Testes de Função Vestibular , Nervo Vestibular/fisiopatologia , Doença Aguda , Adulto , Vestibulopatia Bilateral/complicações , Tontura/etiologia , Feminino , Humanos , Potenciais Evocados Miogênicos Vestibulares/fisiologiaRESUMO
INTRODUCTION: The vestibular implant could become a clinically useful device in the near future. This study investigated the feasibility of restoring the high-frequency dynamic visual acuity (DVA) with a vestibular implant, using the functional Head Impulse Test (fHIT). METHODS: A 72-year-old female, with bilateral vestibulopathy and fitted with a modified cochlear implant incorporating three vestibular electrodes (MED-EL, Innsbruck, Austria), was available for this study. Electrical stimulation was delivered with the electrode close to the lateral ampullary nerve in the left ear. The high-frequency DVA in the horizontal plane was tested with the fHIT. After training, the patient underwent six trials of fHIT, each with a different setting of the vestibular implant: (1) System OFF before stimulation; (2) System ON, baseline stimulation; (3) System ON, reversed stimulation; (4) System ON, positive stimulation; (5) System OFF, without delay after stimulation offset; and (6) System OFF, 25 min delay after stimulation offset. The percentage of correct fHIT scores for right and left head impulses were compared between trials. RESULTS: Vestibular implant stimulation improved the high-frequency DVA compared to no stimulation. This improvement was significant for "System ON, baseline stimulation" (p = 0.02) and "System ON, positive stimulation" (p < 0.001). fHIT scores changed from 19 to 44% (no stimulation) to maximum 75-94% (System ON, positive stimulation). CONCLUSION: The vestibular implant seems capable of improving the high-frequency DVA. This functional benefit of the vestibular implant illustrates again the feasibility of this device for clinical use in the near future.
Assuntos
Vestibulopatia Bilateral/terapia , Implantes Cocleares , Terapia por Estimulação Elétrica , Vestíbulo do Labirinto/fisiopatologia , Acuidade Visual/fisiologia , Idoso , Áustria , Vestibulopatia Bilateral/fisiopatologia , Feminino , Teste do Impulso da Cabeça , Humanos , Resultado do Tratamento , Nervo Vestibular/fisiopatologiaRESUMO
One of the most appealing hypotheses around the aetiopathogenesis of adolescent idiopathic scoliosis attributes the development of the spine deformity to an imbalance in the descending vestibulospinal drive to the muscles resulting in a differential mechanical pull on the spine during the early life stages. In this study, we explored this hypothesis by examining postural and muscle responses to binaural bipolar galvanic vestibular stimulation (GVS) of randomly alternating polarity. Adolescents diagnosed with idiopathic scoliosis (n = 12) and healthy age-matched controls (n = 12) stood quietly with feet together (stance duration 66-102 s), eyes closed and facing forward, while 10 short (2s), transmastoidal, bipolar square wave GVS pulses (0.3-2.0 mA) of randomly alternating polarity were delivered at varying time intervals. Responses depicted in the electromyographic (EMG) activity of bilateral axial and appendicular muscles, vertical reaction forces and segment kinematics were recorded and analysed. Scoliotic patients demonstrated smaller ankle muscle responses and a delayed postural shift to the right relative to controls during anode right/cathode left GVS. When GVS polarity was reversed, patients had a greater soleus short-latency response on the left anodal side, while the rest of the muscle and postural responses were similar between groups. Vestibular stimulation also evoked greater head and upper trunk sway in scoliotic compared with healthy adolescents irrespective of stimulus polarity. Results provide new preliminary evidence for a vestibular imbalance in adolescents with idiopathic scoliosis that is compensated by somatosensory, load-related afferent feedback from the lower limbs during the latter part of the response.
Assuntos
Músculo Esquelético/fisiopatologia , Equilíbrio Postural , Escoliose/fisiopatologia , Potenciais Evocados Miogênicos Vestibulares , Nervo Vestibular/fisiopatologia , Adolescente , Fenômenos Biomecânicos , Estimulação Elétrica/métodos , Retroalimentação Fisiológica , Feminino , Humanos , Contração Muscular , Vestíbulo do Labirinto/fisiopatologiaRESUMO
OBJECTIVE: To analyze the clinical characteristics of acute vestibular neuritis (AVN) according to involvement site. STUDY DESIGN: Retrospective chart analysis. SETTING: Tertiary referral hospital. PATIENTS/INTERVENTIONS: Over a period of 3 years, we reviewed 133 cases of AVN. Patients were classified into three groups: 1) total vestibular neuritis (superior and inferior vestibular nerve involvement [TVN]); 2) superior vestibular neuritis (superior vestibular nerve involvement [SVN]); and 3) inferior vestibular neuritis (inferior vestibular nerve involvement [IVN]). MAIN OUTCOME MEASURE: We analyzed the clinical course and results of vestibular function tests (video-nystagmography, video head impulse test [vHIT], caloric test, and cervical vestibular evoked myogenic potential). RESULTS: In the study, there were 39.9% TVN cases, 48.1% SVN cases, and 12% IVN cases. The number of days to spontaneous nystagmus remission, hospital duration, and follow-up period were shorter in the IVN group than in the SVN and TVN groups. The symptom onset period was longer in the IVN group than in the SVN and TVN groups. Spontaneous nystagmus and head shaking nystagmus amplitude were smaller in the IVN group than in the SVN and TVN groups. Concordance of results between the caloric test, cervical vestibular evoked myogenic potential, and vHIT was relatively low in the IVN group. CONCLUSION: The IVN group had a shorter clinical course and weaker nystagmus in comparison with the TVN and SVN groups. The use of additional vHIT in the diagnosis of AVN can help provide a more accurate diagnosis of the rare subtype of IVN, which can be confused with various central lesions.
Assuntos
Potenciais Evocados Miogênicos Vestibulares/fisiologia , Nervo Vestibular/fisiopatologia , Neuronite Vestibular/diagnóstico , Vestíbulo do Labirinto/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Teste do Impulso da Cabeça/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Testes de Função Vestibular , Neuronite Vestibular/fisiopatologia , Adulto JovemRESUMO
HYPOTHESIS: In superior canal dehiscence (SCD), fluid displacement of the endolymph activates type I vestibular hair cells in the crista of the affected canal and thus irregular superior canal (SC) neurons in Scarpa's ganglion, which provides the neurophysiological basis for the clinical presentation of SCD. BACKGROUND: Patients with SCD display sound- and vibration-induced vertigo/nystagmus and increased amplitudes of vestibular evoked myogenic potentials. METHODS: Extracellular recordings from nâ=â25 primary vestibular neurons of 16 female guinea pigs were analyzed. We recorded from the same vestibular neuron before, during and after creating the dehiscence and after closing the dehiscence. Neurobiotin labeling was employed in nâ=â11 neurons. RESULTS: After SCD, previously unresponsive irregular SC neurons displayed a stimulus-locked increase in discharge during application of air-conducted sound (ACS) or bone-conducted vibration (BCV) for a broad range of frequencies (ACS: 200-4000âHz; BCV: 500-1500âHz). This typical response was only observed for irregular SC neurons (nâ=â19), but not regular SC neurons, or irregular/regular horizontal canal neurons (nâ=â2 each), and was abolished after closing the dehiscence. Eleven irregular SC neurons responsive to ACS and/or BCV were traced back to calyx synapses in the central crista of the affected superior canal by neurobiotin labeling. CONCLUSIONS: Stimulus-locked activation of irregular SC neurons by ACS and BCV is the neurophysiological basis for sound- and vibration-induced vertigo/nystagmus and increased VEMP amplitudes in SCD. The results of the present study help to improve vestibular diagnostics in patients with suspected SCD.
Assuntos
Doenças do Labirinto/fisiopatologia , Potenciais Evocados Miogênicos Vestibulares/fisiologia , Nervo Vestibular/fisiopatologia , Estimulação Acústica/métodos , Animais , Modelos Animais de Doenças , Feminino , Cobaias , Humanos , Pessoa de Meia-Idade , Canais Semicirculares/fisiologia , Testes de Função Vestibular/métodos , Vestíbulo do Labirinto/fisiologiaRESUMO
BACKGROUND: Identification of the nerve of origin in vestibular schwannoma (VS) is an important prognostic factor for hearing preservation surgery. Thus far, vestibular functional tests and magnetic resonance imaging have not yielded reliable results to preoperatively evaluate this information. The development of the video head impulse test (vHIT) has allowed a precise evaluation of each semicircular canal, and its localizing value has been tested for some peripheral vestibular diseases, but not for VS. OBJECTIVE: To correlate patterns of semicircular canal alteration on vHIT to intraoperative identification of the nerve of origin of VSs. METHODS: A total 31 patients with sporadic VSs were preoperatively evaluated with vHIT (gain of vestibule-ocular reflex, overt and covert saccades on each semicircular canal) and then the nerve of origin was surgically identified during surgical resection via retrosigmoid approach. vHIT results were classified as normal, isolated superior vestibular nerve (SVN) pattern, isolated inferior vestibular nerve (IVN) pattern, predominant SVN pattern, and predominant IVN pattern. Hannover classification, cystic component, and distance between the tumor and the end of the internal auditory canal were also considered for analysis. RESULTS: Three patients had a normal vHIT, 12 had an isolated SVN pattern, 5 had an isolated IVN pattern, 7 had a predominant SVN pattern, and 4 had a predominant IVN pattern. vHIT was able to correctly identify the nerve of origin in 89.7% of cases (100% of altered exams). CONCLUSION: The pattern of semicircular canal dysfunction on vHIT has a localizing value to identify the nerve of origin in VSs.
Assuntos
Teste do Impulso da Cabeça/métodos , Neuroma Acústico/fisiopatologia , Canais Semicirculares/fisiopatologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cuidados Pré-Operatórios , Reflexo Vestíbulo-Ocular/fisiologia , Nervo Vestibular/fisiopatologia , Gravação em Vídeo , Adulto JovemRESUMO
OBJECTIVE: Current spread by electrical stimulation via inserted cochlear implant (CI) electrodes and the consequential increase in sound input can affect the equilibrium of patients. The aim of the present study was to clarify the effect of CIs on the equilibrium of patients through cervical vestibular-evoked myogenic potential (cVEMP) testing and static stabilometry performed with the CIs turned on (CI-on) and off (CI-off). METHODS: This prospective study included nine adult patients who underwent unilateral cochlear implantation surgery at our institution. cVEMP testing and stabilometry were performed before surgery and repeated after surgery in the CI-on and CI-off modes. RESULTS: Before surgery, cVEMP responses were diminished in five of the nine patients (55.6%), while the results of stabilometry were poor in six patients (66.7%). After surgery, both cVEMP responses and stabilometry findings in the CI-off mode exhibited significant deterioration relative to the preoperative results (cVEMP: 7/9, 77.8%; stabilometry: 7/9, 77.8%). However, in the CI-on mode, there were significant improvements in both test results relative to the findings in the CI-off mode for all patients. CONCLUSION: CIs compensated for the surgical trauma-induced deterioration in static postural stability when turned on, resulting in a considerable improvement. Our findings suggest that postoperative cVEMP testing in the CI-on and CI-off modes will enable more accurate assessment of the saccule-inferior vestibular nerve system function after cochlear implant surgery.
Assuntos
Implante Coclear , Implantes Cocleares , Complicações Pós-Operatórias/fisiopatologia , Equilíbrio Postural/fisiologia , Doenças Vestibulares/fisiopatologia , Potenciais Evocados Miogênicos Vestibulares/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Nervo Vestibular/fisiopatologiaRESUMO
OBJECTIVES:: The aim of this study was to investigate vertical semicircular canal function in patients with vestibular schwannoma (VS) by video head impulse test (vHIT). METHODS:: Fifteen patients with VS who had not received any treatment, including surgery or stereotactic radiotherapy, before vHIT examination were enrolled. Vestibulo-ocular reflex gain and catch-up saccade in vHIT were evaluated. RESULTS:: Dysfunction of anterior and posterior semicircular canals was detected by vHIT in 26.7% and 60.0%, respectively. Six patients (40.0%) demonstrated abnormalities referable to both vestibular nerve divisions. Abnormalities referable to the superior vestibular nerve were identified in 3 patients (20.0%), while 3 patients (20.0%) demonstrated a pattern indicative of inferior vestibular nerve involvement. Anterior semicircular canal vHIT produced fewer abnormalities than did either horizontal or posterior semicircular canal vHIT. CONCLUSIONS:: Dysfunction of the semicircular canals, including the vertical canals, in patients with VS was detected by vHIT. The anterior semicircular canal was less frequently involved than the horizontal or posterior semicircular canal. The examination of the vertical canals by vHIT is useful in the evaluation of vestibular function in patients with VS.
Assuntos
Teste do Impulso da Cabeça/métodos , Neuroma Acústico/fisiopatologia , Canais Semicirculares/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reflexo Vestíbulo-Ocular , Estudos Retrospectivos , Nervo Vestibular/fisiopatologia , Gravação em VídeoRESUMO
OBJECTIVE: Vestibular symptoms such as dizziness and vertigo are common after head injury and may be due to trauma to the peripheral vestibular system. The pathophysiology of peripheral vestibular symptoms following head injury without temporal bone (TB) fracture, however, is not well understood. Herein, we investigate the histopathology of the peripheral vestibular system of patients who sustained head injury without a TB fracture. STUDY DESIGN: Otopathology study. SETTING: Otopathology laboratory. SUBJECTS AND METHODS: TB of subjects with a history of head injury without TB fractures were included and evaluated by light microscopy. Specimens were assessed for qualitative and quantitative characteristics, such as number of Scarpa's ganglion cells in the superior and inferior vestibular nerves, vestibular hair cell and/or dendrite degeneration in vestibular end organs, presence of vestibular hydrops, and obstruction of the endolymphatic duct. RESULTS: Five cases (n = 5 TBs) had evidence of vestibular pathology. There was a decrease of 48.6% (range, 40%-59%) in the mean count of Scarpa's ganglion cells as compared with that of normative historical age-matched controls. Moderate to severe degeneration of the vestibular membranous labyrinth was identified in the posterior, superior, and lateral canals in several cases (50%, n = 4 TBs). The maculae utriculi and sacculi showed mild to severe degeneration in 2 cases. Additional findings include vestibular hydrops (25%, n = 2 TBs) and blockage of the endolymphatic duct (n = 1 TB). CONCLUSIONS: Otopathologic analysis of patients with a history of head injury without TB fracture demonstrated peripheral vestibular otopathology. Future studies are necessary to determine if otopathology findings are directly attributable to head injury.
Assuntos
Traumatismos Craniocerebrais/patologia , Doenças Vestibulares/patologia , Nervo Vestibular/patologia , Vestíbulo do Labirinto/patologia , Adulto , Biópsia por Agulha , Traumatismos Craniocerebrais/complicações , Feminino , Fraturas Ósseas/patologia , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Otolaringologia , Sistema de Registros , Estudos de Amostragem , Sensibilidade e Especificidade , Manejo de Espécimes , Osso Temporal/lesões , Técnicas de Cultura de Tecidos , Doenças Vestibulares/etiologia , Nervo Vestibular/fisiopatologia , Vestíbulo do Labirinto/fisiopatologiaRESUMO
Facial nerve schwannomas (FS) can symptomatically mimic vestibular schwannomas (VS). In addition, FS can be difficult to distinguish from VS on magnetic resonance imaging (MRI). Although disequilibrium is not uncommon in patients with FS, no previous studies have investigated the vestibular function in such patients. Three cases of FS presented vestibular dysfunction as measured with caloric test, video head impulse test (VHIT), and vestibular evoked myogenic potentials (VEMPs). All patients in this study had a considerable affection of the vestibular function as assessed by the vestibular test panel. Audiovestibular evaluation of FS provides important information that may influence treatment strategy. As VS, FS should be evaluated with vestibular tests prior to intervention.
Assuntos
Neuroma Acústico/diagnóstico , Adulto , Idoso , Nervo Facial/fisiopatologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neuroma Acústico/diagnóstico por imagem , Reflexo , Potenciais Evocados Miogênicos Vestibulares , Nervo Vestibular/fisiopatologia , Vestíbulo do Labirinto/fisiopatologiaRESUMO
Acute unilateral lesions of vestibular graviceptive pathways from the otolith organs and semicircular canals via vestibular nuclei and the thalamus to the parieto-insular vestibular cortex regularly cause deviations of perceived verticality in the frontal roll plane. These tilts are ipsilateral in peripheral and in ponto-medullary lesions and contralateral in ponto-mesencephalic lesions. Unilateral lesions of the vestibular thalamus or cortex cause smaller tilts of the perceived vertical, which may be either ipsilateral or contralateral. Using a neural network model, we previously explained why unilateral vestibular midbrain lesions rarely manifest with rotational vertigo. We here extend this approach, focussing on the direction-specific deviations of perceived verticality in the roll plane caused by acute unilateral vestibular lesions from the labyrinth to the cortex. Traditionally, the effect of unilateral peripheral lesions on perceived verticality has been attributed to a lesion-based bias of the otolith system. We here suggest, on the basis of a comparison of model simulations with patient data, that perceived visual tilt after peripheral lesions is caused by the effect of a torsional semicircular canal bias on the central gravity estimator. We further argue that the change of gravity coding from a peripheral/brainstem vectorial representation in otolith coordinates to a distributed population coding at thalamic and cortical levels can explain why unilateral thalamic and cortical lesions have a variable effect on perceived verticality. Finally, we propose how the population-coding network for gravity direction might implement the elements required for the well-known perceptual underestimation of the subjective visual vertical in tilted body positions.