Limiar Diferencial de mascaramento e potencial evocado auditivo de tronco encefálico em adultos normo-ouvintes com zumbido / Masking Level Difference and Auditory Brainstem ResponseIn Normal Hearing Adults With Tinnitus / Umbral de enmascaramiento diferencial y potencial evocado auditivo del tronco encefálico en adultos con audición normal y tinnitus

Introdução: O zumbido é uma ilusão auditiva consciente, uma sensação sonora não relacionada com uma fonte externa de estimulação. Objetivos: Caracterizar a Acufenometria, Limiar Diferencial de Mascaramento, o questionário de qualidade de vida Inventário de Desvantagem do Zumbido e Potencial Auditivo de Tronco Encefálico em adultos normo-ouvintes com zumbido, com a finalidade de comparar seus achados. Método: Vinte indivíduos do sexo feminino e masculino, entre 20 e 60 anos de idade, normo-ouvintes com queixa de zumbido, foram submetidos ao Acufenometria, Limiar Diferencial de Mascaramento, Inventário de Desvantagem do Zumbido e Potencial Evocado Auditivo de Tronco Encefálico. Resultados: AAcufenometriarevelou que o pitch médio foi de 4,3 KHz à orelha direita e 4,6 KHz à orelha esquerda. O loudness médio foi de 21,7 dBNS à orelha direita e 23,5 dBNS à orelha esquerda. O Limiar Diferencial de Mascaramento médio mostrou-se alterado. O Inventário de Desvantagem do Zumbido médio correspondeu à classificação de grau leve. O Potencial Evocado Auditivo de Tronco Encefálico apresentou parâmetros dentro da normalidade bilateralmente. Conclusão: Constatou-se que adultos normo-ouvintes com queixa de zumbido apresentam zumbido de pitch agudo bilateral com discreto impacto na qualidade de vida, condução adequada das vias auditivas até o tronco encefálico e comprometimento na identificação de sons na presença de ruído, demonstrando que o zumbido pode ter repercussões nas habilidades auditivas centrais. (AU)

Introduction: Tinnitus is a conscious auditory illusion, a sound perception unrelated to any external stimulus source. Objectives: To characterize the Acuphenometry, Masking Level Difference, the quality of life questionnaire Tinnitus Handicap Inventory and Auditory Brainstem Response in normal hearing adults with tinnitus, with the purpose of comparing the findings. Method: Twenty female and male individuals, between 20 and 60 years of age, normal hearing with complaints of tinnitus, underwent Acuphenometry, Masking Level Difference, Tinnitus Handicap Inventory and Auditory Brainstem Response. Results: The Acuphenometry showed the average pitch was 4.3 KHz to the right ear and 4.6 KHz to the left ear. The average loudness was 21.7 dBSL to the right ear and 23.5 dBs to the left ear. The average Masking Level Difference was altered. The average Tinnitus Handicap Inventory corresponded to the classification of mild grade. Auditory Brainstem Response showed parameters within normal range bilaterally. Conclusion: It was found that normal hearing adults with tinnitus complaints have bilateral acute pitch tinnitus with a slight impact on quality of life, appropriate conduction of auditory pathways to the brainstem and impaired identification of sounds in the presence of noise, demonstrating that tinnitus can have repercussions on central auditory skills. (AU)

Introducción: El tinnitus es una ilusión auditiva consciente, una sensación de sonido no relacionada con una fuente externa de estimulación. Objetivos: Caracterizar la coincidencia de tono y volumen, el umbral de enmascaramiento diferencial, el inventario de minusvalía para acúfenos y el potencial auditivo del tronco encefálico en adultos normoyentes con acúfenos, con el fin de comparar sus hallazgos. Método:Veinte sujetos masculinos y femeninos, con edades entre 20 y 60 años, audición normal con tinnitus, fueron sometidos a acúfenos, Umbral de Enmascaramiento Diferencial, Inventario de Desventajas de Tinnitus y Potenciales Evocados Auditivos del Tronco Encefalico. Resultados: La combinación de tono y volumen reveló que el tono promedio era de 4,3 KHz en el oído derecho y de 4,6 KHz en el oído izquierdo. Mientras que el volumen medio fue de 21,7 dBNS para el oído derecho y de 23,5 dBNS para el oído izquierdo. Se modificó el umbral diferencial de enmascaramiento promedio. El Inventario de Desventajas de Tinnitus promedio correspondió a la clasificación de grado leve. El Potenciales Evocados Auditivos del Tronco Encefalico presentó parámetros dentro del rango normal bilateralmente. Conclusión:Se encontró que los adultos normooyentes con quejas de tinnitus presentan tinnitus de tono alto bilateral con leve impacto en la calidad de vida, conducción adecuada de las vías auditivas al tronco encefálico y deterioro en la identificación de sonidos en presencia de ruido, demostrando que Tinnitus puede tener repercusiones en las habilidades auditivas centrales. (AU)

Enmascaramiento en las mesioclusiones / Camouflage in mesiocclusions

Se analiza la difícil tarea de decidir, por parte del especialista, un camuflaje ortodóncico en aquellos pacientes con mesioclusiones verdaderas que no aceptan un tratamiento donde se realice cirugía ortognática. Cuál debe ser el límite que nos impone el caso clínico para poder tomar la decisión de realizar el tratamiento y qué debe esperar el paciente y el profesional en los resultados finales, una vez concluido. Somos los ortodoncistas los que tenemos el deber de decidir qué pacientes podrían ser tratados con camuflaje y cuáles, con cirugía ortognática, pero será el paciente el que tome la decisión final con nuestro asesoramiento (AU)

We discuss the difficult task of deciding, on the part of the specialist, an orthodontic camouflage in those patients with true mesioclusions who do not accept a treatment where orthognathic surgery is performed. What should be the limit imposed by the clinical case in order to make the decision to carry out the treatment and what the patient and the professional should expect in the final results, once concluded. We orthodontists have the duty to decide which patients could be treated with camouflage and which, with orthognathic surgery, but it will be the patient who makes the final decision with our advice (AU)

Enmascaramiento clínico: una revisión de la literatura / Clinical masking: a literature review

Son diversos los métodos planteados para aplicar enmascaramiento, de esta forma es necesario revisar la literatura en búsqueda de consenso. Se revisaron críticamente los métodos utilizados y recomendados por la literatura y sociedades internacionales, en torno a la aplicación de enmascaramiento. Se consultó entre agosto y noviembre de 2015 en PUBMED, SciELO y Google Scholar por estudios acerca de métodos de enmascaramiento utilizados en audiometría. También se revisaron las guías de organizaciones internacionales y lo publicado en libros relacionados con el área de audiología. El método de "La Meseta" es el más referenciado, siendo modificado posteriormente. Existen variaciones en criterios de atenuación interaural, necesidad de enmascaramiento, enmascaramiento inicial, incrementos para obtener la meseta y niveles del efecto de oclusión. Se concluye que la literatura muestra diferencias al momento de decidir cuándo enmascarar y cómo hacerlo. No obstante, se puede establecer criterios comunes en relación a los niveles de atenuación interaural, cuándo enmascarar, valores de efecto de oclusión y metodología. El método de "La Meseta" sigue siendo el más recomendado. La modificación realizada por Yacullo es la más referenciada y recomendada en la literatura actual.

Adequate use of masking is key in the correct diagnosis of hearing loss. Various methods are suggested regarding the application of clinical masking, hence the need to review literature in order to reach a consensus. To critically review the specialized literature and international societies' recommendations regarding clinical masking. From August to November 2015, PUBMED, SciELO and Google Scholar articles on clinical masking methods used in tonal audiometries were consulted, as well as international organization guidelines, and literature in the area of Audiology. Hood's plateau method, later revised, received the most references. The modified versions consider the number of increments needed to determine the true threshold, and the occlusion effect. Optimized methods show the variations regarding interaural attenuation, need for masking, initial masking level, increments to reach "The Plateau", and the occlusion effect. Literature shows differences regarding when and how to use masking; however, common criteria can be established with reference to the levels of interaural attenuation, when to use masking, occlusion effect values and methodology. The plateau method proposed by Hood is still the most recommended. Yacullo's optimization is currently the one with the most references and recommendations in specialized literature.

Estudios experimentales 1 Parte: el ensayo clínico / Experimental studies 1st Part: clinical trial

Los estudios experimentales, se caracterizan por la valoración del efecto de una o más intervenciones, habitualmente de forma comparativa con otra intervención, o un placebo; y el carácter prospectivo, de la recolección de los datos y el seguimiento de los grupos en estudio. Bajo la denominación de estudios experimentales, existe una diversidad de diseños, desde los ensayos clínicos (EC) y sus variantes, hasta los estudios cuasi-experimentales y los experientos naturales. El objetivo de este manuscrito, es reportar los principios básicos, características y estructura de un EC.

Experimental studies are characterized by the assessment of effect of one or more interventions, usually comparatively with other intervention, or placebo; and the prospective nature of data collection and follow-up. Included in the term experimental studies, there are a variety of designs: Clinical trials (CT) and its variants, quasi-experimental studies and natural experiments. The aim of this manuscript is to report basic principles, characteristics and CT structure.

Ion-exchange resin complexation: Masking the bitter taste of cefuroxime axetil / Complejación de la resina de intercambio de iones: enmascaramiento del sabor amargo de cefuroxime acetil

OBJECTIVE: the purpose of this research was to formulate taste masked complexes of cefuroxime axetil and to evaluate them for taste, drug loading and characterized by FTIR, XRD. Tablets were formulated of selected batches and evaluated for drug release and physical parameters. METHODS: complexation technique is used to prepare complexes of drug where ion exchange resins such as Indion® 214, Indion® 234 and Indion® 414 were used with a drug-resin ratio of 1:0.5, 1:1, 1:2. The drug resinates were characterized by Infrared Spectroscopy, DSC and X-Ray Diffraction pattern and evaluated for drug loading and taste. Direct compression method was used to formulate tablets. In vitro dissolution was carried out using USP II apparatus. RESULT: potential taste masking increased with increasing concentration of resin. Indion® 214 resin showed better taste masking effect as compared to Indion® 234 and Indion® 414. Percent of drug loading was maximum at drug : resin ratio of 1:1, after that it decreased. Prolonged (upto 5 h) and slow drug release was observed with resin 214 at higher concentration. CONCLUSIONS: out of three resins chosen, Indion® 214 at higher concentration exhibit excellent taste masking as well as sustained drug release action.

OBJETIVO: el objetivo de esta investigación fue formular los complejos con sabor amargo de cefuroxime acetil y evaluarlos por sabor, carga medicamentosa y caracterización por FTIR, XRD. Las tabletas fueron formuladas a partir de lotes seleccionados y evaluados en busca de la liberación medicamentosa y parámetros físicos. MÉTODOS: la técnica de complejación se utilizó para preparar complejos farmacológicos donde las resinas de intercambio iónico como Indion® 214, Indion® 234 y el Indion® 414 se emplearon a una proporción resina-medicamento de 1:0.5, 1:1, 1:2. Los resinados medicamentosos fueron caracterizados mediante espectroscopia infrarroja, DSC y el patrón de difracción-rayos-X, y evaluados para determinar la carga medicamentosa y el sabor. El método de compresión directa fue empleado para formular las tabletas. Se efectuó una disolución in vitro utilizando el equipo USP II. RESULTADOS: el posible enmascaramiento del sabor aumentó con la creciente concentración de resina. La resina Indion® 214 mostró el mejor enmascaramiento del gusto amargo en comparación con Indion® 234 e Indion® 414. El porcentaje de carga medicamentosa fue máximo en el fármaco: proporción de la resina 1:1, después disminuyó. Se observó una liberación medicamentosa prolongada (hasta 5 h) y lenta con la resina 214 a una mayor concentración. CONCLUSIONES: de las 3 resinas escogidas, Indion®214 a una mayor concentración muestra un excelente enmascaramiento del sabor así como una mantenida acción liberadora del fármaco.

Enmascaramiento vs Oclusión en la evaluación para el implante BAHA con hipocusia neurosensorial profunda unilateral

Con el objetivo de determinar los umbrales auditivos y contrastarlos con los procedimientos de enmascaramiento mínimo y máximo con los de oclusión en usuarios con hipoacusia neurosensorial profunda unilateral, candidatos a implante BAHA, se tomaron 16 candidatos de la Clínica José A. Rivas, los cuales primero fueron evaluados otológicamente y se les descartó alguna patología retrococlear. Ellos decidieron voluntariamente su participación en la investigación y firmaron el consentimiento informado. Se les realizó otoscopia y membrana timpánica, luego la audiometría que evaluó los umbrales mínimos de audición, adicionalmente se realizó la logoaudiometría y la Inmitancia acústica para corroborar la función del oído medio. Seguidamente se realizó la evaluación de audiometría tonal con el BAHA utilizando en el oído con la hipoacusia el procesador DIVINO en campo libre con el enmascaramiento en donde se aplicó un ruido de 15 dB por encima del umbral en el oído con audición normal y 30 dB por encima del umbral aéreo para el masking máximo. Luego se realizó la oclusión, introduciendo material de impresión cubriendo totalmente el CAE. Para los dos procedimientos se tomaron los umbrales de las frecuencias 500 Hz, 1000 Hz, 2000 Hz y 4000 Hz con el parlante a 0 grados azimut. Se encontraron diferencias importantes entre los dos procedimientos; siendo la oclusión, el mejor procedimiento para la evaluación de implante BAHA.

In order to determine the hearing thresholds and compare them with masking procedures with the minimum and maximum occlusion in users with deep unilateral sensorineural Hypoacusis, 16 BAHA Candidates were taken from the Jose A. Rivas Clinic, who were first evaluated otológically and as a result they got negative any retrocochlear pathology. They decided voluntarily their participation in the research and signed informed consent. It was performed an otoscopy and tympanic membrane, then an audiometry that evaluated their minimal hearing thresholds, in addition it was made a logoaudiometry and an acoustic immittance to corroborate the function of the middle ear. Then an evaluation was developed by doing a tonal audiometry using the BAHA in the ear with hypoacusis using the “DIVINO” processor in an open place with the masking where it was applied a noise of 15 dB above the threshold in the ear with normal hearing and 30 dB above the air threshold for the maximum masking. Then the occlusion was performed by introducing impression material covering the entire CAE. For both procedures the thresholds for the frequencies were 500 Hz, 1000Hz, 2000Hz and 4000Hz with the speaker at 0 degrees azimuth. We found significant differences between the procedures, the occlusion is the best procedure for the evaluation of a BAHA implant.

Enmascaramiento. Un tipo de sincronización. Primera parte

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Abstract: Organisms adapt their temporary niche with two complementary mechanisms. The first mechanism is referred to as entrainment of the endogenous biological clock, which circumscribes temporarily the activity of the subject into day or night. The second mechanism is defined as masking, and this refers to an alternative route which does not involve the activity of the pacemaker. It involves, instead, a sharp response of the animal during light-time, inhibiting or enhancing the expression of locomotor activities in nocturnal or diurnal species, respectively. Masking describes the direct and immediate effects on the expression of any biological rhythm induced by the season-dependent signals present in the environment. Moreover, this masking mechanism appears to complement the biological clock entrainment, which is used by organismsto adapt to their specific nocturnal or diurnal niche. Several constraints arise when trying to study the biological clock entrainment or the light-associated oscillators system. Theseare due to the fact that the zeitgeber influences the biological clock and affects the output response of the circadian clock. According to the aforementioned description, it appears the masking effects occur as a natural event and result from an inevitable consequence to the season-dependent life of living organisms. Circadian rhythms do not only reflect the physiological output responses of the biological clocks as their activities also result from a mixture of responses arising either from the masking effects and/or from the entrainment mechanisms driving the timing of the biological clock within the animal. Although conspicuous differences do exist between maskingand entrained- rhythms, both rhythms follow a similar timecourse. Nevertheless, the transition between light and darkness (environmental change) under the masking rhythm results in abrupt changes in the animal behavior activity (i.e, from a resting to an ambulatory activity or viceversa). In contrast, when the environment acts as a zeitgeber under the biological clock entrainment, the behavioural transition of the animal appears to be less abrupt and, therefore, the environment factors affecting the biological rhythms never match. Based on different chronobiological studies in animals, several authors have described different forms of masking mechanisms used by the brain, and classified according to the light-induced decrease or increase locomotor activity responses: a) Positive Masking refers to the increase or decrease of locomotor activity response in a diurnal or nocturnal animal, respectively, as a result of the increase in lighting; b) Negative Masking refers to the decrease of locomotor activity responses as a result of decrease in lighting in a diurnal animal, or an increase in lighting in a nocturnal animal; c) Paradoxical Positive Masking refers either to the increase locomotor activity responses of a nocturnal animal exposed to increase lighting or an increase in locomotor activity responses in a diurnal animal after lighting decreases; d) Paradoxical Negative Masking refers to the decrease of locomotor activity responses in a nocturnal animal when lighting is decreased, or to the decrease of locomotor activity responses in a diurnal animal when lighting is increased. In addition to the aforementioned classification of different masking mechanisms on the behavioral locomotor activity responses in both diurnal and nocturnal animals, other authors classify different forms of masking, based on the neural mechanisms that generate the masking effects. Authors defined the occurence of different forms of masking effects when enviromental factors (i.e, light, darkness) produce direct or indirect effects on the cyrcadian rhythm in an animal. Thus, a) Type I masking occurs when the environment produces a direct effect on the circadian rhythm output; b) Type II masking occurs when behavioral changes in the animal affect other physiological brainrhythms, for instance, an increase or decrease of behavioral locomotor activity may affect the temperature rhythm of an organism, enhancing the expression of an altered activity on the biological clock; c) Type III masking occurs when physiological or biochemical changes alter the neural output of the biological clock that conveys the time-related information of the biological rhythm; for instance, physiological or pathological conditions have been shown to affect the functional activity of specific neural pathways and their membrane receptors involved in the regulation of the body temperature. Such situations appear to modify the phase of the body temperature rhythm with the phase of the biological clock, which both rhythms appear to match under basal conditions. The sensibility limits necessary to generate the inhibition of the synthesis and release of melatonine, in rats and hamster, suggest the involvement of the rods, the predominant photoreceptor in the rodent retina. Nevertheless, studies the mutant mice rd/rd (the mutation rd generates the total loss of photoreceptors type rods and a considerable loss of photoreceptors type cones) presented an inhibition in the synthesis and release of the melatonine and locomotor activity induced by the light. This suggests that the photoreceptors type cones and rods are not necessary to mediate the effects of the light on the locomotor activity and that the light masking depends on another type of contained photoreceptor in the retina. Some studies report the loss of the rhythmycity in drinking, locomotion or sleep-wakefulness, not only when the animals are kept in light constant, also when the animals are kept under lightdarkness cycles (L:D). Other studies that involve to mutant mice of the two genescryptocromos, which they are arrhythmic in constant conditions; they show a SCN functional diminished, light pulses applied in the subjective night do not generate alterations in the inhibition of the locomotor activity induced by the light. This suggests the loss of the masking responses induced by light. Certainly, these results point to a loss or attenuation of the masking by the SCN lesion. On the other hand, other works showing a persistence of the masking pd drinking and locomotor activity in L:D conditions after the SCN lesions. The lesions of other structures of the rodent visual system alter the light masking. It is more a significant increase of the masking in subjects with IGL lesion is observed. Subsequently, it was reported that the masking induced by the light was more significant in mice that were submitted to an NGLd lesions, which suggests that the increase in the masking to the light observed after the IGL lesions are probably due to an incidental damage of the NGLd. It also has been reported that the light masking increase after the visual cortex lesions in hamster and mice. The mutant mice clock shows brilliant light pulses: between 100 to 1600 lux they induce a complete suppression of the locomotor activity (negative masking). On the other hand, dim light pulses induce an increment of the basal levels of the locomotor activity (positive masking) in a similar way to that of the normal subjects. The participation of other genes clock in the regulation of the light-masking has not been specific. The masking is not a limited phenomenon to conditions of laboratory. There are few examples of the direct effects of light on the temporary organization of the behavior in wildlife. An impressive case is the owl primate (Aotus lemurinus griseimembra), which shows a pattern of locomotor activity that depends on the lunar cycle. This primate is nocturnal, but its activity increases (positive masking) when the luminescence is found between 0.1 and 0.5 lux, the luminescence generated precisely by the brightness of the moon. Intensities of light lower to this diminish the locomotor activity (negative masking) of the subject. The masking mechanism is an important process in the adaptation of an organism to its environment as it confers this the capacity to respond quickly to a sudden change in environmental conditions. Since the functional point of view the masking contributes to an increment in the amplitude of a entrainment rhythm, promotes direct responses to geophysical variables that the organism selects that they optimize its evolution and its adaptation to its temporary niche, all this contributes to an increase in the probability of survival of the subject to its environment.