RESUMEN

BACKGROUND AND PURPOSE: A sensitive and frequent clinical sign of a vestibular tone imbalance is the tilt of the perceived subjective visual vertical (SVV). There are no data yet focusing on lesion location at the cortical level as a factor for predicting compensation from the tilt of the SVV. METHODS: With modern voxelwise lesion behavior mapping analysis, the present study determines whether lesion location in 23 right-hemispheric cortical stroke patients with an otolith dysfunction could predict the compensation of a vestibular tone imbalance in the chronic stage. RESULTS: Our statistical anatomical lesion analysis revealed that lesions of the posterior insular cortex are involved in vestibular otolith compensation. CONCLUSION: The insular cortex appears to be a critical anatomical region for predicting a tilt of the SVV as a chronic disorder in stroke patients.

Asunto(s)

Membrana Otolítica , Accidente Cerebrovascular , Corteza Cerebral/patología , Humanos , Membrana Otolítica/patología , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/diagnóstico por imagen , Accidente Cerebrovascular/patología

RESUMEN

OBJECTIVE: Previous study suggested that estradiol (E2) plays an important role in otolith shedding by regulating the expression of otoconin 90 (OC90). The purpose of this article is to provide further data on the effect and mechanism of E2 on the morphology of otolith. METHODS: The rats receiving bilateral ovariectomy (OVX) were used as animal models. Co-immunoprecipitation was used to observe the relationship between estrogen receptor (ER) and estrogen-related receptor α (ERRα). The morphology of otolith was observed under the scanning electron microscopy. Western blotting and qPCR were used for quantitative analysis of the roles of ER and ERRα in regulating OC90 expression. RESULTS: The looser otoliths were observed in rats receiving bilateral OVX, which could be reversed by supplementation with E2. The level of ERRα was decreased in bilateral OVX rats. ER and ERRα interacted with each other on the regulation of the expression of OC90. CONCLUSION: Our results suggest ER and ERRα are both important downstream receptors involved in regulating OC90 expression in utricles of rats, and ERRα probably functions by interacting with ER. This provides evidence for the mechanism of otolith shedding. And it may be significant for future studies of targeted prevention and therapies for benign paroxysmal positional vertigo.

Asunto(s)

Proteínas de Unión al Calcio/genética , Estrógenos/metabolismo , Membrana Otolítica/metabolismo , Receptores de Estrógenos/genética , Animales , Estradiol/metabolismo , Estrógenos/genética , Femenino , Humanos , Membrana Otolítica/patología , Ovariectomía , Ratas , Receptor Relacionado con Estrógeno ERRalfa

RESUMEN

OBJECTIVE: To describe a case of benign paroxysmal positional vertigo (BPPV) resulting in reversible horizontal semicircular canalith jam successfully treated with horizontal canal occlusion. A brief literature review of similar cases was performed. METHODS: Case report and literature review. RESULTS: A 68-year-old female presented with apogeotropic positional nystagmus, attributed to reversible horizontal canalith jam mimicking cupulolithiasis that was refractory to tailored repositioning maneuvers across months. She was unable to work due to the severity of her symptoms. She underwent surgical occlusion of the affected canal with immediate resolution of her symptoms. A literature review revealed similar cases of canalith jam mimicking cupulolithiasis. CONCLUSIONS: Reversible canalith jam, in which particles moving with horizontal head position alternate between obstructing the semicircular canal and resting on the cupula, can mimic signs of cupulolithiasis. This variant of BPPV can be effectively managed with surgical canal occlusion should symptoms fail to resolve after tailored repositioning maneuvers.

Asunto(s)

Vértigo Posicional Paroxístico Benigno , Laberintitis , Membrana Otolítica , Canales Semicirculares , Enfermedades Vestibulares/diagnóstico , Anciano , Vértigo Posicional Paroxístico Benigno/diagnóstico , Vértigo Posicional Paroxístico Benigno/etiología , Vértigo Posicional Paroxístico Benigno/fisiopatología , Vértigo Posicional Paroxístico Benigno/cirugía , Diagnóstico Diferencial , Técnicas de Diagnóstico Otológico , Femenino , Humanos , Laberintitis/diagnóstico , Laberintitis/fisiopatología , Laberintitis/cirugía , Litiasis/diagnóstico , Membrana Otolítica/patología , Membrana Otolítica/fisiopatología , Procedimientos Quirúrgicos Otológicos/métodos , Canales Semicirculares/patología , Canales Semicirculares/cirugía , Resultado del Tratamiento

RESUMEN

BACKGROUND: Otoconia-related vertigo and balance deficits are common in humans, but the molecular etiology is unknown at present. OBJECTIVE: In order to study mechanisms of otoconia formation and maintenance, we have investigated whether otoconin-90 (Oc90), the predominant otoconial constituent protein, and the NADPH oxidase Nox3, an essential regulatory protein for otoconia formation, are functionally interlinked. METHODS: We performed balance behavioral, electrophysiological, morphological and molecular cellular analyses. RESULTS: Double heterozygous mutant mice for Oc90 and Nox3 show severe imbalance, albeit less profound than double null mutants. In contrast, single heterozygous mutant mice have normal balance. Double heterozygous mice have otoconia defects and double null mice have no otoconia. In addition, some hair bundles in the latter mice go through accelerated degeneration. In vitro calcification analysis in cells stably expressing these proteins singly and doubly shows much more intense calcification in the double transfectants. CONCLUSIONS: Oc90 and Nox3 augment each other's function, which is not only critical for otoconia formation but also for hair bundle maintenance.

Asunto(s)

Proteínas de Unión al Calcio/genética , Proteínas de la Matriz Extracelular , NADPH Oxidasas , Membrana Otolítica , Vértigo/genética , Animales , Proteínas de la Matriz Extracelular/metabolismo , Ratones , NADPH Oxidasas/genética , Membrana Otolítica/patología

RESUMEN

Rationale: Mutations of SLC26A4 that abrogate pendrin, expressed in endolymphatic sac, cochlea and vestibule, are known to cause autosomal recessive sensorineural hearing loss with enlargement of the membranous labyrinth. This is the first study to demonstrate the feasibility of gene therapy for pendrin-related hearing loss. Methods: We used a recombinant viral vector to transfect Slc26a4 cDNA into embryonic day 12.5 otocysts of pendrin-deficient knock-out (Slc26a4∆/∆ ) and pendrin-deficient knock-in (Slc26a4tm1Dontuh/tm1Dontuh ) mice. Results: Local gene-delivery resulted in spatially and temporally limited pendrin expression, prevented enlargement, failed to restore vestibular function, but succeeded in the restoration of hearing. Restored hearing phenotypes included normal hearing as well as sudden, fluctuating, and progressive hearing loss. Conclusion: Our study illustrates the feasibility of gene therapy for pendrin-related hearing loss, suggests differences in the requirement of pendrin between the cochlea and the vestibular labyrinth, and documents that insufficient pendrin expression during late embryonal and early postnatal development of the inner ear can cause sudden, fluctuating and progressive hearing loss without obligatory enlargement of the membranous labyrinth.

Asunto(s)

Terapia Genética , Pérdida Auditiva Sensorineural/genética , Pérdida Auditiva Sensorineural/terapia , Audición/genética , Mutación/genética , Transportadores de Sulfato/genética , Animales , Cóclea/metabolismo , Dependovirus , Oído Interno/metabolismo , Saco Endolinfático/embriología , Saco Endolinfático/metabolismo , Células Epiteliales/metabolismo , Células Ciliadas Auditivas/metabolismo , Concentración de Iones de Hidrógeno , Ratones Endogámicos C57BL , Ratones Noqueados , Membrana Otolítica/patología , Fenotipo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Estría Vascular/metabolismo , Transportadores de Sulfato/metabolismo , Transcripción Genética

RESUMEN

OBJECTIVE: To describe a variant of posterior canal benign paroxysmal positional vertigo (BPPV). STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Fifteen patients with symptoms of BPPV and oculomotor evidence of activation of posterior semicircular canal (P-SCC) cupula that arises when sitting up from Dix-Hallpike maneuver (DH). INTERVENTION: All patients were examined with videonystagmography and underwent brain magnetic resonance imaging (MRI). RESULTS: All patients showed up-beating nystagmus with ipsilateral torsional component when coming up from right or left side DH. Most patients described vertiginous symptoms when sitting up from bed and many described severe non-positional disequilibrium. Eight patients had been treated with Epley canalith repositioning maneuver (CRM) at our clinic for posterior canal BPPV. Four of them were re-tested within an hour for CRM effectiveness and the rest, a week later. Three patients had been diagnosed with BPPV and were being treated with CRM in other institutions. Four patients showed these findings but they had not previously undergone CRM. All patients were treated with CRM without success, but they resolved their positional vertigo by means of Brandt Daroff exercises. No patient showed evidence of central vestibular disorder. CONCLUSION: We propose a P-SCC canalolithiasis limited to the periampullar portion by means of an anatomical restriction of distal movement of the otoconial debris. This syndrome seems to be more frequent early after CRM of classical P-SCC canalolithiasis. Close attention to ocular movement on sitting up after DH on patients is warranted.

Asunto(s)

Vértigo Posicional Paroxístico Benigno/fisiopatología , Movimientos Oculares/fisiología , Sedestación , Adulto , Vértigo Posicional Paroxístico Benigno/terapia , Femenino , Humanos , Masculino , Persona de Mediana Edad , Nistagmo Patológico/diagnóstico , Nistagmo Patológico/fisiopatología , Membrana Otolítica/patología , Examen Físico , Estudios Retrospectivos , Canales Semicirculares/patología

RESUMEN

In this paper, we first briefly describe the mechanical model of cupula deformation with the appropriate analytical solution. Then, we present the numerical solution of the same problem and compare it with the analytical one. Besides, we provide another numerical solution based on the Finite Element Method procedure, in an effort to encompass a more realistic approach to the problem such as considering the real geometry of the SCCs and the obstruction of the fluid flow during head movement due to the presence of otoconia. As a result, we obtain fifty solutions for a head rotation angle in a range from 0° to 120°, taking into account that such a manoeuvre lasts exactly 3 seconds. In the end, we present a mobile client-server application for visualising the finite element solutions in a way that is convenient for the clinical practice.

Asunto(s)

Membrana Otolítica/patología , Canales Semicirculares/patología , Algoritmos , Análisis de Elementos Finitos , Humanos , Análisis Numérico Asistido por Computador , Rotación

RESUMEN

Otoconia are crucial for the correct processing of positional information and orientation. Mice lacking otoconia cannot sense the direction of the gravity vector and cannot swim properly. This study aims to characterize the behavior of mergulhador (mlh), otoconia-deficient mutant mice. Additionally, the central catecholamine levels were evaluated to investigate possible correlations between behaviors and central neurotransmitters. A sequence of behavioral tests was used to evaluate the parameters related to the general activity, sensory nervous system, psychomotor system, and autonomous nervous system, in addition to measuring the acquisition of spatial and declarative memory, anxiety-like behavior, motor coordination, and swimming behavior of the mlh mutant mice. As well, the neurotransmitter levels in the cerebellum, striatum, frontal cortex, and hippocampus were measured. Relative to BALB/c mice, the mutant mlh mice showed 1) reduced locomotor and rearing behavior, increased auricular and touch reflexes, decreased motor coordination and increased micturition; 2) decreased responses in the T-maze and aversive wooden beam tests; 3) increased time of immobility in the tail suspension test; 4) no effects in the elevated plus maze or object recognition test; 5) an inability to swim; and 6) reduced turnover of dopaminergic system in the cerebellum, striatum, and frontal cortex. Thus, in our mlh mutant mice, otoconia deficiency reduced the motor, sensory and spatial learning behaviors likely by impairing balance. We did not rule out the role of the dopaminergic system in all behavioral deficits of the mlh mutant mice.

Asunto(s)

Proteínas de la Membrana/genética , Mutación/genética , Neurotransmisores/metabolismo , Membrana Otolítica/patología , Enfermedades Vestibulares/genética , Animales , Conducta Exploratoria/fisiología , Suspensión Trasera , Masculino , Aprendizaje por Laberinto/fisiología , Ratones , Ratones Endogámicos BALB C , Ratones Mutantes , Actividad Motora , Desempeño Psicomotor/fisiología , Reconocimiento en Psicología/fisiología , Aprendizaje Espacial , Natación , Enfermedades Vestibulares/etiología

RESUMEN

OBJECTIVE: Low vitamin D levels have been associated with and could play a role in the pathogenesis of idiopathic benign paroxysmal positional vertigo (iBPPV). Since otoconia degeneration contributes to iBPPV and a lack of vitamin D may impact otoconia structure and integrity, we proposed a negative association between vitamin D levels and levels of a proposed circulatory biomarker for otolithic degeneration, otolin-1. STUDY DESIGN: Cross-sectional clinical study. SETTING: Clinical research center. PATIENTS: Seventy-nine men and women ranging in age from 22 to 95 years old without known vertigo. INTERVENTIONS: Diagnostic. MAIN OUTCOME MEASURES: Blood levels of 25-OH vitamin D and otolin-1. RESULTS: Previously, we had reported higher otolin-1 levels in older age groups. The majority of the subjects (83%) had vitamin D levels that were below 40 ng/ml. Vitamin D level was lowest in the young and increased with age before declining in subjects 70 years of age and older (p = 0.005). There was a negative correlation between vitamin D and otolin-1 levels of subjects over 70 (r = -0.36, p = 0.036). CONCLUSION: Our results demonstrate a relationship between vitamin D and otolin-1. The majority of our subjects had abnormally low vitamin D levels, but only those over 70 years of age showed a negative correlation with high otolin-1 levels. We postulate that a seasonal drop in vitamin D may not be sufficient for otoconia fragmentation and ultimately iBPPV, rather, chronically low vitamin D maybe required to induce otoconia degeneration.

Asunto(s)

Vértigo Posicional Paroxístico Benigno/sangre , Proteínas de la Matriz Extracelular/sangre , Vitamina D/sangre , Adulto , Anciano , Anciano de 80 o más Años , Vértigo Posicional Paroxístico Benigno/etiología , Biomarcadores/sangre , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Membrana Otolítica/patología , Adulto Joven

RESUMEN

OBJECTIVE: To elucidate the clinical features and vestibular symptoms of patients with otolith organ dysfunction in the presence of normal function of the semicircular canals. METHODS: We reviewed the clinical records of 277 consecutive new patients with balance disorders who underwent testing of cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) as well as caloric testing and video head impulse testing (vHIT). RESULTS: We identified 76 patients who showed normal caloric responses and normal vHIT findings in each SCC plane, but abnormal responses in cVEMP and/or oVEMP testing. Benign paroxysmal positional vertigo (BPPV) was the most common diagnosis. 37% of patients could not be categorized into any of the established clinical entities that could cause a balance disorder and did not show sensorineural hearing loss. The most common clinical manifestation in the idiopathic cases was recurrent rotatory vertigo with a duration of 1-12 h. CONCLUSIONS: The most common diagnosis of otolith organ-specific vestibular dysfunction was BPPV. The most common clinical manifestation in the idiopathic cases was recurrent rotatory vertigo. SIGNIFICANCE: Specific dysfunction of the otolith organs occurs in association with some of the undiagnosed patients with recurrent rotatory vertigo.

Asunto(s)

Enfermedades del Laberinto/diagnóstico , Membrana Otolítica/patología , Adulto , Anciano , Anciano de 80 o más Años , Pruebas Calóricas , Femenino , Humanos , Enfermedades del Laberinto/clasificación , Masculino , Persona de Mediana Edad , Membrana Otolítica/fisiopatología , Equilibrio Postural , Potenciales Vestibulares Miogénicos Evocados

RESUMEN

OBJECTIVE: Over the last decade, ocular vestibular evoked myogenic potentials (oVEMPs) have evolved as a new clinical test for dynamic otolith (predominantly utricular) function. The aim of this review is to give an update on the neurophysiological foundations of oVEMPs and their implications for recording and interpreting oVEMP responses in clinical practice. CONCLUSION: Different lines of anatomical, neurophysiological, and clinical evidence support the notion that oVEMPs measure predominantly contralateral utricular function, while cervical cVEMPs are an indicator of ipsilateral saccular function. Bone-conducted vibration (BCV) in the midline of the forehead at the hairline (Fz) or unilateral air-conducted sound (ACS) are commonly used as stimuli for oVEMPs. It is recommended to apply short stimuli with short rise times for obtaining optimal oVEMP responses. Finally, this review summarizes the clinical application and interpretation of oVEMPs, particularly for vestibular neuritis, Ménière's disease, superior canal dehiscence and "challenging" patients.

Asunto(s)

Membrana Otolítica/fisiopatología , Potenciales Vestibulares Miogénicos Evocados , Conducción Ósea , Medicina Basada en la Evidencia , Humanos , Membrana Otolítica/anatomía & histología , Membrana Otolítica/patología , Sáculo y Utrículo/fisiopatología

RESUMEN

The objective of the present study was to evaluate the otolith function in the patients presenting with idiopathic benign paroxysmal positional vertigo (pBPPV) attributable to the occlusion of the posterior semicircular canal (PSCC) of the inner ear with the use of vestibular evoked myogenic potentials (VEMP). Cervical (cVEMP) and ocular VEMP (oVEMP) were measured in 34 patients with idiopathic pBPPV before and 7 days after the treatment by means of reposition maneuvers. The results of the repeated Dix-Hallpike test performed 7 days after the repositioning maneuver were negative in 27 patients and positive in 7 patients. There was no statistically significant difference in the amplitude of cervical VEMP between the healthy and affected ears either before or after the repositioning treatment. The measurement of oVEMP revealed a reduction of the response amplitude on the affected side. The average values of the plnl on the healthy side were 12.84±1.09 and those on the affected side 4.62±0.69 (p<0,05). The successful repositioning treatment resulted in a significant increase of the oVEMP amplitude on the affected side (p<0,05). In the patients presenting with the persistent symptoms of pBPPV, the repositioning maneuvers did not cause an appreciable increase in the amplitude of oVEMP on the affected side (p<0.05). The results of the present study give evidence that pBPPV of the posterior semicircular canal is associated with the impairment of the function of the receptor structures of the utriculus and the preserved function of the succulus as suggested by the reduction of the oVEMP amplitude and clinically significant asymmetry of ocular VEMP on the affected side with intact cervical VEMP on both sides. The successful treatment of pBPPV of PSCC with the use of the liberatory maneuver results in the increase of the oVEMP amplitude on the affected side increases while the response asymmetry between both sides significantly decreases which indicates the repair of the utriculus otolith function.

Asunto(s)

Vértigo Posicional Paroxístico Benigno , Membrana Otolítica , Posicionamiento del Paciente/métodos , Potenciales Vestibulares Miogénicos Evocados/fisiología , Vértigo Posicional Paroxístico Benigno/diagnóstico , Vértigo Posicional Paroxístico Benigno/etiología , Vértigo Posicional Paroxístico Benigno/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Membrana Otolítica/patología , Membrana Otolítica/fisiopatología , Evaluación del Resultado de la Atención al Paciente , Recuperación de la Función , Reproducibilidad de los Resultados , Canales Semicirculares/patología , Canales Semicirculares/fisiopatología , Pruebas de Función Vestibular/métodos

RESUMEN

BACKGROUND: Although benign paroxysmal positional vertigo and endolymphatic hydrops are considered to be distinct diagnoses, a minority of vertiginous patients exhibit features of both conditions. This coincidence has been reported previously in the literature, and is reviewed here in terms of possible aetiology. RESULTS AND CONCLUSION: A new hypothesis to account for both conditions is offered, implicating free-floating degenerating debris from the otolithic apparatus. It is postulated that the gelatinous/proteinaceous component may account for an osmotically induced hydrops, while the calcified fragments may induce positional vertigo.

Asunto(s)

Vértigo Posicional Paroxístico Benigno/etiología , Hidropesía Endolinfática/etiología , Anciano , Vértigo Posicional Paroxístico Benigno/patología , Hidropesía Endolinfática/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Membrana Otolítica/patología , Vestíbulo del Laberinto/patología

RESUMEN

Sensory mismatch between actual motion information and anticipated sensory patterns (internal model) is the etiology of motion sickness (MS). Some evidence supports that hippocampus might involve the neural storage of the "internal model". This study established an "internal model" acquisition-retention behavioral model using a repeated habituation rotation training protocol. We tried to identify the hippocampal subregion involved in "internal model" retention using chemical lesion methods. Hippocampal kinases (CaMK, CaMKIV, CREB and ERK1/2) phosphorylation in the target subregion was assayed and the effects of kinase inhibitors (KN93 or U0126) on "internal model" retention were investigated. The activities of potential kinases (CaMKII and CREB) were also examined in otoliths deficit het/het mice. In habituated rats, CA1 lesion reproduced MS-related behavioral responses on "internal model" retention day. Habituation training increased CaMKII and CREB activity but had no effect on CaMKIV and ERK1/2 activity in the CA1, while inhibition of CaMKII but not ERK1/2 impaired "internal model" retention. In het/het mice, CaMKII and CREB were not activated in the CA1 on the retention day. These results suggested that CaMKII/CREB pathway might potentially contribute to the storage of the "internal model" in the hippocampal CA1 after motion sickness induced by vestibular stimulation.

Asunto(s)

Región CA1 Hipocampal/metabolismo , Proteína de Unión a CREB/genética , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/genética , Mareo por Movimiento/genética , Membrana Otolítica/metabolismo , Transducción de Señal , Animales , Bencilaminas/farmacología , Butadienos/farmacología , Región CA1 Hipocampal/patología , Región CA1 Hipocampal/fisiopatología , Proteína de Unión a CREB/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/antagonistas & inhibidores , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Proteína Quinasa Tipo 4 Dependiente de Calcio Calmodulina/antagonistas & inhibidores , Proteína Quinasa Tipo 4 Dependiente de Calcio Calmodulina/genética , Proteína Quinasa Tipo 4 Dependiente de Calcio Calmodulina/metabolismo , Modelos Animales de Enfermedad , Regulación de la Expresión Génica , Masculino , Ratones , Ratones Endogámicos C57BL , Proteína Quinasa 1 Activada por Mitógenos/antagonistas & inhibidores , Proteína Quinasa 1 Activada por Mitógenos/genética , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/antagonistas & inhibidores , Proteína Quinasa 3 Activada por Mitógenos/genética , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Mareo por Movimiento/metabolismo , Mareo por Movimiento/patología , Mareo por Movimiento/fisiopatología , Nitrilos/farmacología , Membrana Otolítica/patología , Membrana Otolítica/fisiopatología , Fosforilación/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Rotación , Sulfonamidas/farmacología

RESUMEN

CONCLUSION: The results showed a gradual detachment of otoconia in the utricle after a single event of head vibration, possibly explaining the frequent recurrence of BPPV attacks and persistent dizziness after trauma. OBJECTIVES: This study developed a murine model of traumatic BPPV and observed the changes in otoconia detachment over time. METHODS: Six-week-old CBA mice were used in this study. Otoconia detachment was induced by vibrating the head for 2 min. Utricles of mice were harvested from different groups: before the head vibration and 1 day, 1 week, 1 month, and 3 months after vibration application. Using scanning electron microscopy and ImageJ software, the percentage of the intact area of otoconia in the utricle was calculated. Hearing thresholds were compared among the groups. RESULTS: The mean (± SD) percentages of the intact area of otoconia in the utricle were 98.1% ± 1.7% before the vibration and 93.6% ± 1.7%, 88.9% ± 5.3%, 78.2% ± 20.9%, and 38.9% ± 24.1% at 1 day, 1 week, 1 month, and 3 months after the vibration, respectively. The percentage decreased significantly over time after the vibration (p < .001). The hearing thresholds were not different among the groups.

Asunto(s)

Vértigo Posicional Paroxístico Benigno , Modelos Animales de Enfermedad , Animales , Umbral Auditivo , Masculino , Ratones Endogámicos CBA , Membrana Otolítica/patología , Vibración

RESUMEN

OBJECTIVES/HYPOTHESIS: Benign paroxysmal positional vertigo (BPPV) is the most common vestibular disorder with an incidence between 10.7 and 17.3 per 100,000 persons per year. The mechanism for BPPV has been postulated to involve displaced otoconia resulting in canalithiasis. Although particulate matter has been observed in the endolymph of affected patients undergoing posterior canal occlusion surgery, an otoconial origin for the disease is still questioned. STUDY DESIGN: In this study, particulate matter was extracted from the posterior semicircular canal of two patients and examined with scanning electron microscopy. METHODS: The samples were obtained from two patients intraoperatively during posterior semicircular canal occlusion. The particles were fixed, stored in ethanol, and chemically dehydrated. The samples were sputter coated and viewed under a scanning electron microscope. Digital images were obtained. RESULTS: Intact and degenerating otoconia with and without linking filaments were found attached to amorphous particulate matter. Many otoconia appeared to be partially embedded in a gel matrix, presumably that which encases and anchors the otoconia within the otolith membrane, whereas others stood alone with no attached filaments and matrix. The otoconia measured roughly 2 to 8 µm in length and displayed a uniform outer shape with a cylindrical bulbous body and a 3 + 3 rhombohedral plane at each end. CONCLUSIONS: These findings suggest that the source of the particulate matter in the semicircular canals of patients with BPPV is broken off fragments of the utricular otolithic membrane with attached and detached otoconia. LEVEL OF EVIDENCE: NA Laryngoscope, 127:709-714, 2017.

Asunto(s)

Vértigo Posicional Paroxístico Benigno/patología , Vértigo Posicional Paroxístico Benigno/cirugía , Membrana Otolítica/ultraestructura , Canales Semicirculares/cirugía , Canales Semicirculares/ultraestructura , Anciano , Vértigo Posicional Paroxístico Benigno/diagnóstico , Biopsia con Aguja , Femenino , Estudios de Seguimiento , Humanos , Inmunohistoquímica , Microscopía Electrónica de Rastreo , Persona de Mediana Edad , Membrana Otolítica/patología , Procedimientos Quirúrgicos Otológicos/métodos , Material Particulado , Muestreo , Canales Semicirculares/patología , Índice de Severidad de la Enfermedad , Resultado del Tratamiento

RESUMEN

Otoconia are minute biocrystals composed of glycoproteins, proteoglycans, and CaCO3 , and are indispensable for sensory processing in the utricle and saccule. Otoconia abnormalities and degeneration can cause or facilitate crystal dislocation to the ampulla, leading to vertigo and imbalance in humans. In order to better understand the molecular mechanism controlling otoconia formation and maintenance, we have examined the spatial and temporal expression differences of otoconial genes in the mouse inner ear at developmental, mature and aging stages using whole transcriptome sequencing (RNA-Seq) and quantitative RT-PCR. We show that the expression levels of most otoconial genes are much higher in the utricle and saccule compared with other inner ear tissues before postnatal stages in C57Bl/6J mice, and the expression of a few of these genes is restricted to the embryonic utricle and saccule. After the early postnatal stages, expression of all otoconial genes in the utricle and saccule is drastically reduced, while a few genes gain expression dominance in the aging ampulla, indicating a potential for ectopic debris formation in the latter tissue at old ages. The data suggest that the expression of otoconial genes is tightly regulated spatially and temporally during developmental stages and can become unregulated at aging stages. Birth Defects Research (Part A) 106:613-625, 2016. © 2016 Wiley Periodicals, Inc.

Asunto(s)

Envejecimiento/genética , Membrana Otolítica/metabolismo , Transcriptoma/genética , Vértigo/genética , Animales , Carbonato de Calcio/metabolismo , Oído Interno/metabolismo , Oído Interno/patología , Regulación de la Expresión Génica , Glicoproteínas/biosíntesis , Glicoproteínas/genética , Humanos , Ratones , Organogénesis/genética , Membrana Otolítica/patología , Proteoglicanos/biosíntesis , Proteoglicanos/genética , Sáculo y Utrículo/metabolismo , Sáculo y Utrículo/patología , Vértigo/patología

RESUMEN

The leading symptoms of bilateral vestibulopathy (BVP) are postural imbalance and unsteadiness of gait that worsens in darkness and on uneven ground. There are typically no symptoms while sitting or lying under static conditions. A minority of patients also have movement-induced oscillopsia, in particular while walking. The diagnosis of BVP is based on a bilaterally reduced or absent function of the vestibulo-ocular reflex (VOR). This deficit is diagnosed for the high-frequency range of the angular VOR by a bilaterally pathologic bedside head impulse test (HIT) and for the low-frequency range by a bilaterally reduced or absent caloric response. If the results of the bedside HIT are unclear, angular VOR function should be quantified by a video-oculography system (vHIT). An additional test supporting the diagnosis is dynamic visual acuity. Cervical and ocular vestibular-evoked myogenic potentials (c/oVEMP) may also be reduced or absent, indicating impaired otolith function. There are different subtypes of BVP depending on the affected anatomic structure and frequency range of the VOR deficit: impaired canal function in the low- and/or high-frequency VOR range only and/or otolith function only; the latter is very rare. The etiology of BVP remains unclear in more than 50% of patients: in these cases neurodegeneration is assumed. Frequent known causes are ototoxicity mainly due to gentamicin, bilateral Menière's disease, autoimmune diseases, meningitis and bilateral vestibular schwannoma, as well as an association with cerebellar degeneration (cerebellar ataxia, neuropathy, vestibular areflexia syndrome=CANVAS). In general, in the long term there is no improvement of vestibular function. There are four treatment options: first, detailed patient counseling to explain the cause, etiology, and consequences, as well as the course of the disease; second, daily vestibular exercises and balance training; third, if possible, treatment of the underlying cause, as in bilateral Menière's disease, meningitis, or autoimmune diseases; fourth, if possible, prevention, i.e., being very restrictive with the use of ototoxic substances, such as aminoglycosides. In the future vestibular implants may also be an option.

Asunto(s)

Vestibulopatía Bilateral/fisiopatología , Reflejo Vestibuloocular/fisiología , Vestibulopatía Bilateral/diagnóstico , Vestibulopatía Bilateral/etiología , Movimientos Oculares , Humanos , Membrana Otolítica/patología , Membrana Otolítica/fisiopatología

RESUMEN

Some individuals with noise-induced hearing loss (NIHL) also report balance problems. These accompanying vestibular complaints are not well understood. The present study used a rat model to examine the effects of noise exposure on the vestibular system. Rats were exposed to continuous broadband white noise (0-24 kHz) at an intensity of 116 dB sound pressure level (SPL) via insert ear phones in one ear for three hours under isoflurane anesthesia. Seven days after the exposure, a significant increase in ABR threshold (43.3 ± 1.9 dB) was observed in the noise-exposed ears, indicating hearing loss. Effects of noise exposure on vestibular function were assessed by three approaches. First, fluorescein-conjugated phalloidin staining was used to assess vestibular stereocilia following noise exposure. This analysis revealed substantial sensory stereocilia bundle loss in the saccular and utricular maculae as well as in the anterior and horizontal semicircular canal cristae, but not in the posterior semicircular canal cristae. Second, single unit recording of vestibular afferent activity was performed under pentobarbital anesthesia. A total of 548 afferents were recorded from 10 noise-treated rats and 12 control rats. Noise exposure produced a moderate reduction in baseline firing rates of regular otolith afferents and anterior semicircular canal afferents. Also a moderate change was noted in the gain and phase of the horizontal and anterior semicircular canal afferent's response to sinusoidal head rotation (1 and 2 Hz, 45°/s peak velocity). Third, noise exposure did not result in significant changes in gain or phase of the horizontal rotational and translational vestibulo-ocular reflex (VOR). These results suggest that noise exposure not only causes hearing loss, but also causes substantial damage in the peripheral vestibular system in the absence of immediate clinically measurable vestibular signs. These peripheral deficits, however, may lead to vestibular disorders over time.

Asunto(s)

Pérdida Auditiva Provocada por Ruido/fisiopatología , Ruido/efectos adversos , Vestíbulo del Laberinto/fisiopatología , Animales , Potenciales Evocados Auditivos del Tronco Encefálico , Femenino , Masculino , Neuronas Aferentes/patología , Membrana Otolítica/patología , Ratas , Ratas Long-Evans , Ratas Sprague-Dawley , Reflejo Vestibuloocular , Rotación , Canales Semicirculares/patología , Nervio Vestibular/fisiopatología

RESUMEN

BPPV is generally the most common cause of vertigo, caused by a pinch-off of tiny calcium carbonate crystals (called the otoconia or the otoliths) from the macula utriculi, most frequently due to the degenerative processes or a trauma, whereby the crystals, under the action of gravity in certain head positions coinciding with its direction, arrive to some of the semicircular canals, usually the posterior one, due to the existent anatomical circumstances and relationships, thus creating an inadequate stimulus of the cupular senses while floating through the endolymph and provoking symptoms of a strong and short-term dizziness. Two main clinical forms can be distinguished: canalolythiasis, with an accommodation of otolithic debris in the semicircular canal, and cupulolythiasis, with their location immediately next to the cupular sense. The diagnosis is established by a positive positioning test, Dix-Hallpike for the posterior and the supine roll for the lateral canal. Although one can expect a spontaneous recovery subsequent to few weeks or months, various methods of otolith repositioning to a less sensitive place lead to a prompt improvement while reducing or withdrawing the symptoms completely. These guidelines are intended for all who treat the BPPV in their work, with an intention to assist in the diagnosis and application of an appropriate therapeutic method.

Asunto(s)

Vértigo Posicional Paroxístico Benigno/diagnóstico , Vértigo Posicional Paroxístico Benigno/terapia , Guías de Práctica Clínica como Asunto , Vértigo Posicional Paroxístico Benigno/clasificación , Croacia , Humanos , Membrana Otolítica/patología , Posicionamiento del Paciente