Prediction of the univariant two-phase coexistence line of the tetrahydrofuran hydrate from computer simulation.

In this work, the univariant two-phase coexistence line of the tetrahydrofuran (THF) hydrate is determined from 100 to 1000 bar by molecular dynamics simulations. This study is carried out by putting in contact a THF hydrate phase with a stoichiometric aqueous solution phase. Following the direct coexistence technique, the pressure is fixed, and the coexistence line is determined by analyzing if the hydrate phase grows or melts at different values of temperature. Water is described using the well-known TIP4P/Ice model. We have used two different models of THF based on the transferable parameters for phase equilibria-united atom approach (TraPPE-UA), the original (flexible) TraPPe-UA model and a rigid and planar version of it. Overall, at high pressures, small differences are observed in the results obtained by both models. However, large differences are observed in the computational efforts required by the simulations performed using both models, being the rigid and planar version much faster than the original one. The effect of the unlike dispersive interactions between the water and THF molecules is also analyzed at 250 bar using the rigid and planar THF model. In particular, we modify the Berthelot combining rule via a parameter ξO-THF that controls the unlike water-THF dispersive interactions. We analyze the effect on the dissociation temperature of the hydrate when ξO-THF is modified from 1.0 (original Berthelot combining rule) to 1.4 (modified Berthelot combining rule). We use the optimized value ξO-THF = 1.4 and the rigid THF model in a transferable way to predict the dissociation temperatures at other pressures. We find excellent agreement between computer simulation predictions and experimental data taken from the literature.

Dissociation line and driving force for nucleation of the nitrogen hydrate from computer simulation.

In this work, we determine the dissociation line of the nitrogen (N2) hydrate by computer simulation using the TIP4P/Ice model for water and the TraPPE force field for N2. We use the solubility method proposed recently by some of us to evaluate the dissociation temperature of the hydrate at different pressures, from 500 to 1500 bar. Particularly, we calculate the solubility of N2 in the aqueous solution when it is in contact with a N2-rich liquid phase and when in contact with the hydrate phase via planar interfaces as functions of temperature. Since the solubility of N2 decreases with temperature in the first case and increases with temperature in the second case, both curves intersect at a certain temperature that determines the dissociation temperature at a given pressure. We find a good agreement between the predictions obtained in this work and the experimental data taken from the literature in the range of pressures considered in this work. From our knowledge of the solubility curves of N2 in the aqueous solution, we also determine the driving force for nucleation of the hydrate, as a function of temperature, at different pressures. In particular, we use two different thermodynamic routes to evaluate the change in chemical potential for hydrate formation. Although the driving force for nucleation slightly decreases (in absolute value) when the pressure is increased, our results indicate that the effect of pressure can be considered negligible in the range of pressures studied in this work. To the best of our knowledge, this is the first time the driving force for nucleation of a hydrate that exhibits crystallographic structure sII, along its dissociation line, is studied from computer simulation.

Effect of pressure on the carbon dioxide hydrate-water interfacial free energy along its dissociation line.

We investigate the effect of pressure on the carbon dioxide (CO2) hydrate-water interfacial free energy along its dissociation line using advanced computer simulation techniques. In previous works, we have determined the interfacial energy of the hydrate at 400 bars using the TIP4P/Ice and TraPPE molecular models for water and CO2, respectively, in combination with two different extensions of the Mold Integration technique [J. Colloid Interface Sci. 623, 354 (2022) and J. Chem. Phys. 157, 134709 (2022)]. Results obtained from computer simulation, 29(2) and 30(2) mJ/m2, are found to be in excellent agreement with the only two measurements that exist in the literature, 28(6) mJ/m2 determined by Uchida et al. [J. Phys. Chem. B 106, 8202 (2002)] and 30(3) mJ/m2 determined by Anderson et al. [J. Phys. Chem. B 107, 3507 (2002)]. Since the experiments do not allow to obtain the variation of the interfacial energy along the dissociation line of the hydrate, we extend our previous studies to quantify the effect of pressure on the interfacial energy at different pressures. Our results suggest that there exists a correlation between the interfacial free energy values and the pressure, i.e., it decreases with the pressure between 100 and 1000 bars. We expect that the combination of reliable molecular models and advanced simulation techniques could help to improve our knowledge of the thermodynamic parameters that control the interfacial free energy of hydrates from a molecular perspective.

Solubility of carbon dioxide in water: Some useful results for hydrate nucleation.

In this paper, the solubility of carbon dioxide (CO2) in water along the isobar of 400 bar is determined by computer simulations using the well-known TIP4P/Ice force field for water and the TraPPE model for CO2. In particular, the solubility of CO2 in water when in contact with the CO2 liquid phase and the solubility of CO2 in water when in contact with the hydrate have been determined. The solubility of CO2 in a liquid-liquid system decreases as the temperature increases. The solubility of CO2 in a hydrate-liquid system increases with temperature. The two curves intersect at a certain temperature that determines the dissociation temperature of the hydrate at 400 bar (T3). We compare the predictions with T3 obtained using the direct coexistence technique in a previous work. The results of both methods agree, and we suggest 290(2) K as the value of T3 for this system using the same cutoff distance for dispersive interactions. We also propose a novel and alternative route to evaluate the change in chemical potential for the formation of hydrates along the isobar. The new approach is based on the use of the solubility curve of CO2 when the aqueous solution is in contact with the hydrate phase. It considers rigorously the non-ideality of the aqueous solution of CO2, providing reliable values for the driving force for nucleation of hydrates in good agreement with other thermodynamic routes used. It is shown that the driving force for hydrate nucleation at 400 bar is larger for the methane hydrate than for the carbon dioxide hydrate when compared at the same supercooling. We have also analyzed and discussed the effect of the cutoff distance of dispersive interactions and the occupancy of CO2 on the driving force for nucleation of the hydrate.

Solubility of Methane in Water: Some Useful Results for Hydrate Nucleation.

In this paper, the solubility of methane in water along the 400 bar isobar is determined by computer simulations using the TIP4P/Ice force field for water and a simple LJ model for methane. In particular, the solubility of methane in water when in contact with the gas phase and the solubility of methane in water when in contact with the hydrate has been determined. The solubility of methane in a gas-liquid system decreases as temperature increases. The solubility of methane in a hydrate-liquid system increases with temperature. The two curves intersect at a certain temperature that determines the triple point T3 at a certain pressure. We also determined T3 by the three-phase direct coexistence method. The results of both methods agree, and we suggest 295(2) K as the value of T3 for this system. We also analyzed the impact of curvature on the solubility of methane in water. We found that the presence of curvature increases the solubility in both the gas-liquid and hydrate-liquid systems. The change in chemical potential for the formation of hydrate is evaluated along the isobar using two different thermodynamic routes, obtaining good agreement between them. It is shown that the driving force for hydrate nucleation under experimental conditions is higher than that for the formation of pure ice when compared at the same supercooling. We also show that supersaturation (i.e., concentrations above those of the planar interface) increases the driving force for nucleation dramatically. The effect of bubbles can be equivalent to that of an additional supercooling of about 20 K. Having highly supersaturated homogeneous solutions makes possible the spontaneous formation of the hydrate at temperatures as high as 285 K (i.e., 10K below T3). The crucial role of the concentration of methane for hydrate formation is clearly revealed. Nucleation of the hydrate can be either impossible or easy and fast depending on the concentration of methane which seems to play the leading role in the understanding of the kinetics of hydrate formation.

Simulation of the CO2 hydrate-water interfacial energy: The mold integration-guest methodology.

The growth pattern and nucleation rate of carbon dioxide hydrate critically depend on the precise value of the hydrate-water interfacial free energy. There exist in the literature only two independent experimental measurements of this thermodynamic magnitude: one obtained by Uchida et al. [J. Phys. Chem. B 106, 8202 (2002)], 28(6) mJ/m2, and the other by Anderson and co-workers [J. Phys. Chem. B 107, 3507 (2003)], 30(3) mJ/m2. Recently, Algaba et al. [J. Colloid Interface Sci. 623, 354 (2022)] have extended the mold integration method proposed by Espinosa and co-workers [J. Chem. Phys. 141, 134709 (2014)] to deal with the CO2 hydrate-water interfacial free energy (mold integration-guest or MI-H). Computer simulations predict a value of 29(2) mJ/m2, in excellent agreement with experimental data. The method is based on the use of a mold of attractive wells located at the crystallographic positions of the oxygen atoms of water molecules in equilibrium hydrate structures to induce the formation of a thin hydrate slab in the liquid phase at coexistence conditions. We propose here a new implementation of the mold integration technique using a mold of attractive wells located now at the crystallographic positions of the carbon atoms of the CO2 molecules in the equilibrium hydrate structure. We find that the new mold integration-guest methodology, which does not introduce positional or orientational information of the water molecules in the hydrate phase, is able to induce the formation of CO2 hydrates in an efficient way. More importantly, this new version of the method predicts a CO2 hydrate-water interfacial energy value of 30(2) mJ/m2, in excellent agreement with experimental data, which is also fully consistent with the results obtained using the previous methodology.

Density functional theory for the prediction of interfacial properties of molecular fluids within the SAFT-γ coarse-grained approach.

Recently, we have proposed the SAFT-VR Mie MF DFT approach [Algaba et al., Phys. Chem. Chem. Phys., 2019, 21, 11937-11948] to investigate systems that exhibit fluid-fluid interfaces. This formalism is based on the combination of the Statistical Associating Fluid Theory for attractive potentials of variable range using Mie intermolecular potential (SAFT-VR Mie) and a Density Functional Theory (DFT) treatment of the free energy. A mean-field approach is used to evaluate the attractive term, neglecting the pair correlations associated to attractions. This theory has been combined with reported SAFT-γ Coarse-Grained (CG) Mie force fields to provide an excellent description of the vapor-liquid interface of carbon dioxide and water pure fluids. The present work is a natural and necessary extension of this previous study. We assess the adequacy of the proposed methodology for dealing with inhomogeneous fluid systems of large complex molecules, in particular carbon tetrafluoride and sulfur hexafluoride greenhouse gases, the refrigerant 2,3,3,3-tetrafluoro-1-propene, and the long-chain n-decane and n-eicosane hydrocarbons. The obvious diversity of these fluids, their chemical and industrial interest, and the fact of that SAFT-γ CG Mie force fields have been reported for them justify such choice. With the aim of testing the theory, we perform Molecular Dynamics simulations in the canonical ensemble using the direct coexistence technique for the same models. We focus both on bulk, such as coexistence diagrams and vapor pressure curves, as well as interfacial properties, including surface tension. The comparison of the theoretical predictions with the computational results as well as with experimental data taken from the literature demonstrates the reliability and generalization of this method for dealing simultaneously with vapor-liquid equilibrium and interfacial phenomena. Hence, it appears as a potential tool for the interface analysis, with the main advantage over molecular simulation of low computational cost, and solving the experimental difficulties in accurately measuring the surface tension of certain systems.

Simulation of the carbon dioxide hydrate-water interfacial energy.

HYPOTHESIS: Carbon dioxide hydrates are ice-like nonstoichiometric inclusion solid compounds with importance to global climate change, and gas transportation and storage. The thermodynamic and kinetic mechanisms that control carbon dioxide nucleation critically depend on hydrate-water interfacial free energy. Only two independent indirect experiments are available in the literature. Interfacial energies show large uncertainties due to the conditions at which experiments are performed. Under these circumstances, we hypothesize that accurate molecular models for water and carbon dioxide combined with computer simulation tools can offer an alternative but complementary way to estimate interfacial energies at coexistence conditions from a molecular perspective. CALCULATIONS: We have evaluated the interfacial free energy of carbon dioxide hydrates at coexistence conditions (three-phase equilibrium or dissociation line) implementing advanced computational methodologies, including the novel Mold Integration methodology. Our calculations are based on the definition of the interfacial free energy, standard statistical thermodynamic techniques, and the use of the most reliable and used molecular models for water (TIP4P/Ice) and carbon dioxide (TraPPE) available in the literature. FINDINGS: We find that simulations provide an interfacial energy value, at coexistence conditions, consistent with the experiments from its thermodynamic definition. Our calculations are reliable since are based on the use of two molecular models that accurately predict: (1) The ice-water interfacial free energy; and (2) the dissociation line of carbon dioxide hydrates. Computer simulation predictions provide alternative but reliable estimates of the carbon dioxide interfacial energy. Our pioneering work demonstrates that is possible to predict interfacial energies of hydrates from a truly computational molecular perspective and opens a new door to the determination of free energies of hydrates.

Molecular dynamics of liquid-liquid equilibrium and interfacial properties of aqueous solutions of methyl esters.

In this work, the liquid-liquid phase equilibria and interfacial properties of methyl ester + water binary mixtures are determined at atmospheric pressure and from 278 to 358 K combining the direct coexistence technique and molecular dynamics simulations. Methyl esters are modelled using new parametrizations based on the united atom TraPPE model force field proposed recently by us [E. Feria, J. Algaba, J. M. Míguez, A. Mejía, P. Gómez-Álvarez and F. J. Blas, Phys. Chem. Chem. Phys., 2019, 22, 4974-4983] that are able to predict the vapour-liquid interfacial properties of pure methyl esters with high accuracy. In the case of water, we consider the well-known TIP4P/2005 model, the most popular rigid and non-polarizable model to describe the interfacial properties of pure water. The simulations are performed using the direct coexistence technique in the isothermal-isobaric or NPzT ensemble in combination with molecular dynamics. We obtain density profiles, temperature-densities and temperature-composition projections of the phase diagrams, and interfacial tensions. The liquid-liquid interfacial tension is calculated from the normal and tangential components of the pressure tensor according to the mechanical virial route. We pay attention particularly to the ability of the molecular models in predicting the experimental behavior of the systems. Simulation results are able to account for the liquid-liquid phase equilibria of these binary mixtures, in good agreement with the experimental data taken from the literature. Unfortunately, experimental values for interfacial tensions are substantially overestimated by predictions from computer simulations in all cases. To our knowledge, this is the first time that the liquid-liquid phase equilibrium and interfacial properties of methyl ester + water mixtures have been predicted from computer simulations.

Preferential Orientations and Anomalous Interfacial Tensions in Aqueous Solutions of Alcohols.

Literature studies on interfacial tension versus temperature between normal alcohols and water show that it increases with temperature and exhibits a maximum value at a given temperature depending on the molecular weight of the alcohol. This very unusual behavior is supposedly accompanied by the formation of monolayers of alcohol molecules oriented preferentially at the interface, a structural issue not confirmed until now. We use molecular-based models for water and alcohols in combination with molecular dynamics simulations to provide physical insights, from a molecular perspective, into the structural and thermodynamic behavior at the liquid-liquid interfaces of aqueous solutions of alcohols.

Vapour-liquid phase equilibria and interfacial properties of fatty acid methyl esters from molecular dynamics simulations.

We have determined the phase equilibria and interfacial properties of a methyl ester homologous series (from methyl acetate to methyl heptanoate) using direct simulations of the vapour-liquid interfaces. The methyl esters are modelled using the united atom approach in combination with transferable parameters for phase equilibria (TraPPE) force fields for alkanes, alkenes, carbon dioxide, ethers, and carboxylic acids in a transferable way. This allows us to take into account explicitly both dispersive and coulombic interactions, as well as the repulsive Pauli-exclusion interactions. Simulations are performed in the NVT or canonical ensemble using molecular dynamics. Vapour-liquid surface tension is determined using the virial route, i.e., evaluating the normal and tangential components of the pressure tensor along the simulation box. We have also calculated density profiles, coexistence densities, vapour pressures, surface entropies and enthalpies, and interfacial thickness as functions of temperature, as well as the normal boiling temperatures and the critical temperatures, densities, and pressures for each member of the series. Special attention is paid to the comparison between experimental data taken from the literature and our results obtained using molecular dynamics simulations. We also analyze the effect of increasing the molecular weight of the methyl esters (at fixed temperature) on all the properties considered, with special emphasis on phase equilibria envelopes and surface tension. The TraPPE force fields transferred from other molecules and chemical families are able to predict very accurately the experimental vapour-liquid phase envelopes of methyl esters. We also compare the results obtained from simulations of the surface tension, with experimental data taken from the literature. To our knowledge, this is the first time that vapour-liquid phase equilibria and interfacial properties, and particularly surface tension, of this methyl ester homologous series are obtained using computer simulation.

An accurate density functional theory for the vapor-liquid interface of chain molecules based on the statistical associating fluid theory for potentials of variable range for Mie chainlike fluids.

A new Helmholtz free energy density functional is presented to predict the vapor-liquid interface of chainlike molecules. The functional is based on the last version of the statistical associating fluid theory for potentials of variable range for homogeneous Mie chainlike fluids (SAFT-VR Mie). Following the standard formalism, the density functional theory (SAFT-VR Mie DFT) is constructed using a perturbative approach in which the free energy density contains a reference term to describe all the short-range interactions treated at the local level, and a perturbative contribution to account for the attractive perturbation which incorporates the long-range dispersive interactions. In this first work, we use a mean-field version of the theory in which the pair correlations are neglected in the attractive term. The SAFT-VR Mie DFT formalism is used to examine the effect of molecular chain length and the repulsive exponent of the intermolecular potential on density profiles and surface tension of linear chains made up of up to six Mie (λr - 6) segments with different values of the repulsive exponent of the intermolecular potential. Theoretical predictions from the theory are compared directly with molecular simulation data for density profiles and surface tension of Mie chainlike molecules taken from the literature. Agreement between theory and simulation data is good for short-chain molecules under all thermodynamic conditions of coexistence considered. Once the theory has proven that it is able to predict the interfacial properties, and particularly interfacial tension, the SAFT-VR Mie DFT formalism is used to predict the interfacial behavior of two new coarse-grained models for carbon dioxide and water recently proposed in the literature. In particular, the theoretical formalism, in combination with the coarse-grained models for carbon dioxide and water, is able to predict the interfacial properties of these important substances in a reasonable way.

Expresión de p63 y p73 en neurinomas del acústico y estudio de su posible relevancia clínica / Expression of p63 and p73 in acoustic neuroma and its possible clinical relevance

Objetivos: Determinar la expresión de p73 y p63 en muestras de neurinomas del acústico y estudiar su posible relevancia clínica. Material y método: Se realiza un estudio retrospectivo de 34 neurinomas del acústico intervenidos durante un período de tres años (2001-2003). Se revisan sus historias clínicas y se realiza un estudio inmunohistoquímico para valorar la expresión de p63 y p73 en las muestras histológicas y la correlación con los hallazgos clínicos más relevantes. Resultados: En el 41% de las muestras se observó una sobre-expresión de p63 y p73 siendo la correlación entre ambas proteínas del 100%. La edad de los pacientes con tinción positiva era mayor que la de los pacientes con tinción negativa sin llegar esta diferencia a ser estadísticamente significativa. El tamaño tumoral era mayor en los casos positivos, pero la diferencia tampoco ha llegado a niveles significativos. No existe correlación entre la expresión de los marcadores y el sexo, lado anatómico ni audiometría. Discusión y conclusión: Se observa inmunotinción positiva para p63 y p73 en casi la mitad de los neurinomas estudiados. A pesar de encontrar que estas proteínas están más expresadas en casos de mayor edad y mayor tamaño, la diferencia no ha llegado a valores significativos, posiblemente por el número limitado de muestras en el análisis. Sin embargo, la expresión de estas proteínas en casi la mitad de los pacientes tratados, puede significar que juegan un papel en el desarrollo y progresión de estos tumores, aunque sería necesario realizar estudios futuros para determinar este papel(AU)

Objectives: Assess p63 and p73 expression in acoustic neuroma and its correlation with clinical and radiological findings. Materials and methods: medical records of 34 patients who were operated on for acoustic neuroma during a 3-year period (2001-2003) were evaluated retrospectively. Immunohistochemical analysis of the schwannoma was performed with p63 and p73 antibodies and clinical patient characteristics were correlated with the immunoreactivity results. Results: 41% of the acoustic neuroma specimens showed p63 and p73 staining. Correlation between both proteins was 100%. Age of the patients tended to be older when staining was positive, but no statistical significance was achieved. Likewise, tumour size was bigger for positive tumours but, again, this difference was not statistically significant. There was no correlation between gender and immunostaining. Discussion and Conclusions: Expression of p63 and p73 was demonstrated in almost half of the patients studied. Although both proteins were more prevalent in older patients and bigger tumours, this difference was not statistically significant, probably due to the reduced sample size. No differences were found in laterality, gender or audiogram. However, the expression of these two proteins in almost half of the tumours shows that they can play a role in the development and progression of acoustic neuromas, although further studies are needed(AU)

Expression of p63 and p73 in acoustic neuroma and its possible clinical relevance.

OBJECTIVES: Assess p63 and p73 expression in acoustic neuroma and its correlation with clinical and radiological findings. MATERIALS AND METHODS: medical records of 34 patients who were operated on for acoustic neuroma during a 3-year period (2001-2003) were evaluated retrospectively. Immunohistochemical analysis of the schwannoma was performed with p63 and p73 antibodies and clinical patient characteristics were correlated with the immunoreactivity results. RESULTS: 41% of the acoustic neuroma specimens showed p63 and p73 staining. Correlation between both proteins was 100%. Age of the patients tended to be older when staining was positive, but no statistical significance was achieved. Likewise, tumour size was bigger for positive tumours but, again, this difference was not statistically significant. There was no correlation between gender and immunostaining. DISCUSSION AND CONCLUSIONS: Expression of p63 and p73 was demonstrated in almost half of the patients studied. Although both proteins were more prevalent in older patients and bigger tumours, this difference was not statistically significant, probably due to the reduced sample size. No differences were found in laterality, gender or audiogram. However, the expression of these two proteins in almost half of the tumours shows that they can play a role in the development and progression of acoustic neuromas, although further studies are needed.

Island cartilage tympanoplasty in revision cases: anatomic and functional results.

We report our experience with island cartilage tympanoplasty in revision cases and assess the anatomical and functional outcomes. We conducted a retrospective chart review at a tertiary referral center for patients who underwent revision tympanoplasty using cartilage with the island technique without mastoidectomy between January 2002 and December 2008. 60 cases were included in the study and successful closure without reperforation was obtained in 52 of 60 patients (87%). Three failed cases underwent a subsequent procedure endaurally with a positive result (92% accumulated success rate). Average postoperative pure-tone audiometry air-bone gap was 13 ± 7 dB compared with 21 ± 11 dB preoperatively (p = 0.004). An overall postoperative air-bone gap of 20 dB or less was achieved in 46 of the 60 patients (76.7%). Tympanoplasty with island cartilage grafting is a reliable procedure for revision cases with excellent anatomic results as well as significant improvement of hearing.

Miringoplastia con cartílago "en isla". Resultados anatómicos y funcionales de 122 casos / Island cartilage myringoplasty. Anatomical and functional results in 122 cases

Introducción y objetivos: En las perforaciones timpánicas con «alto riesgo» de fracaso como son perforaciones grandes, anteriores y/o peritubáricas, reperforaciones, patología de mucosa de oído medio, disfunción tubárica, atelectasia, etc. el porcentaje de fracaso de las miringoplastias es más elevado. Se ha descrito que los materiales que clásicamente se emplean en las miringoplastias (fascia y pericondrio) pueden jugar un papel en este hecho y la miringoplastia con cartílago ofrece mejores resultados. En este trabajo exponemos nuestra experiencia con la miringoplastia con cartílago y describimos la técnica empleada. Métodos: Estudio retrospectivo donde se revisan las historias clínicas de miringoplastias con cartílago realizadas de forma consecutiva durante un período de 5 años (2002–2007). Resultados: Se estudia una muestra de 99 pacientes y 122 intervenciones. Más del 66% de los casos son perforaciones que afectan a más de 3 cuadrantes de la membrana y el 26% de los casos fueron cirugías de revisión tras fracasos previos. A pesar de estos datos a priori desfavorables, la tasa de cierre de perforación de esta serie de 122 casos es del 92%. Los resultados funcionales en los casos de timpanoplastia tipo I muestran una mejoría de la transmisión aérea media con valores estadísticamente significativos. Discusión: Consideramos que la reconstrucción de los defectos timpánicos con cartílago es una alternativa recomendable en determinados casos que denominamos casos de «alto riesgo». Los resultados de esta serie ponen de manifiesto este hecho y además consideramos que son reproducibles de forma sencilla. Conclusiones: Creemos que la miringoplastia con cartílago debe ser tenida en cuenta en los casos que a priori sean desfavorables y donde una miringoplastia con uso de fascia o pericondrio puede fracasar (AU)

Introduction and objectives: In certain situations (“high risk perforations”) such as large perforations, revision cases, middle ear pathology, eustachian tube dysfunction and atelectatic ears, the failure rate of myringoplasty is high. Some authors have suggested that the materials most frequently used for myringoplasty (fascia and perichondrium) may have a role in this failure rate. Cartilage myringoplasty, however, achieves good results in these “high risk” cases. The purpose of this study is to analyze our results and describe the technique. Methods: A retrospective study of all consecutive patient charts for cartilage myringoplasties performed in a 5-year period (2002–2007) was carried out. Results: During the study period, cartilage was used in 99 patients (122 cases). More than 66% of the cases were large perforations and 26% of the cases were revision cases. Successful closure was achieved in 92% of the cases and the functional results show an improvement in the air-bone gap average with statistical significance for type I tympanoplasties. Discussion: The reconstruction of tympanic membrane perforations with cartilage is recommended in certain cases (“high risk” perforations). The results described here show that the anatomical and functional results are good and we consider the technique easy to learn. Conclusions: We consider cartilage myringoplasty a technique that could be used in “high risk” perforations where a technique using fascia or perichondrium may have a higher risk of failure (AU)

[Island cartilage myringoplasty. Anatomical and functional results in 122 cases]. / Miringoplastia con cartílago "en isla". Resultados anatómicos y funcionales de 122 casos.

INTRODUCTION AND OBJECTIVES: In certain situations ("high risk perforations") such as large perforations, revision cases, middle ear pathology, eustachian tube dysfunction and atelectatic ears, the failure rate of myringoplasty is high. Some authors have suggested that the materials most frequently used for myringoplasty (fascia and perichondrium) may have a role in this failure rate. Cartilage myringoplasty, however, achieves good results in these "high risk" cases. The purpose of this study is to analyze our results and describe the technique. METHODS: A retrospective study of all consecutive patient charts for cartilage myringoplasties performed in a 5-year period (2002-2007) was carried out. RESULTS: During the study period, cartilage was used in 99 patients (122 cases). More than 66% of the cases were large perforations and 26% of the cases were revision cases. Successful closure was achieved in 92% of the cases and the functional results show an improvement in the air-bone gap average with statistical significance for type I tympanoplasties. DISCUSSION: The reconstruction of tympanic membrane perforations with cartilage is recommended in certain cases ("high risk" perforations). The results described here show that the anatomical and functional results are good and we consider the technique easy to learn. CONCLUSIONS: We consider cartilage myringoplasty a technique that could be used in "high risk" perforations where a technique using fascia or perichondrium may have a higher risk of failure.

[Aerosol therapy in treatment of childhood otitis media with effusion]. / La aerosolterapia en el tratamiento de la otitis media serosa infantil.

INTRODUCTION AND OBJECTIVES: We address the efficacy of aerosol therapy in the treatment of otitis media with effusion during childhood. We study audiometric recovery in comparison with other classic treatments. MATERIAL AND METHODS: This is a retrospective analysis of 37 patients suffering from otitis media with effusion treated with aerosols. We analyze the pure tone audiometry gap results for the whole sample of patients. We also evaluate the characteristics of the group of patients that had previously required surgery and the group withdrawn from aerosol therapy for not responding. RESULTS: Thirty seven patients with a mean age of 6.8 years met the inclusion criteria. Audiometric tests were performed at the beginning of the treatment and after one month, 3 months and finally 6-12 months. In audiometric terms, 76% of the patients achieved results similar to those obtained after surgery. Seven patients were withdrawn from treatment due to poor or no response to aerosol therapy or due to a lack of collaboration. Two patients developed complications not related to aerosol therapy (tympanic perforation and cholesteatoma pearl). CONCLUSION: The efficacy of aerosol therapy is comparable to that obtained with classic treatments. We have found no differences in the outcomes obtained in the group previously treated with surgery. We found no indicators of poor response in those patients where the treatment failed.

La aerosolterapia en el tratamiento de la otitis media serosa infantil / Aerosol therapy in treatment of childhood otitis media with effusion

Introducción y objetivos: Comprobamos la eficacia de la aerosolterapia en el tratamiento de la otitis serosa infantil. Valoramos el nivel de recuperación auditiva en comparación con los tratamientos clásicos. Material y método: Realizamos un estudio retrospectivo de 37 pacientes pediátricos tratados con aerosolterapia por otitis media serosa. Valoramos los resultados del umbral audiométrico diferencial obtenidos en la muestra general. Valoramos asimismo las características del grupo de los pacientes que previamente habían requerido cirugía y del grupo de pacientes que abandonaron el protocolo de aerosolterapia por mala evolución. Resultados: Treinta y siete pacientes cumplieron los criterios de inclusión con una edad media de 6,8 años. Se realizaron controles audiométricos al inicio, al mes, a los 3 meses y a los 6 o 12 meses. El 76% de los pacientes obtuvo resultados audiométricos al año de seguimiento equiparables a los obtenidos con cirugía. Siete pacientes interrumpieron la aerosolterapia por mala evolución o falta de colaboración y en dos casos la necesidad de la cirugía se produjo por recurrencias de la patología tras resolución inicial al año. Dos pacientes presentaron complicaciones no directamente atribuibles a la aerosolterapia (perforación, perla de colesteatoma). Conclusión: La eficacia de la aerosolterapia es comparable a la obtenida con los tratamientos clásicos. No observamos diferencias en los resultados en el grupo que previamente había requerido cirugía. No detectamos factores indicadores de mala respuesta en el grupo en el que la aerosolterapia fracasó (AU)

Introduction and Objectives: We address the efficacy of aerosol therapy in the treatment of otitis media with effusion during childhood. We study audiometric recovery in comparison with other classic treatments. Material and Methods: This is a retrospective analysis of 37 patients suffering from otitis media with effusion treated with aerosols. We analyze the pure tone audiometry gap results for the whole sample of patients. We also evaluate the characteristics of the group of patients that had previously required surgery and the group withdrawn from aerosol therapy for not responding. Results: Thirty seven patients with a mean age of 6.8 years met the inclusion criteria. Audiometric tests were performed at the beginning of the treatment and after one month, 3 months and finally 6, 12 months. In audiometric terms, 76% of the patients achieved results similar to those obtained after surgery. Seven patients were withdrawn from treatment due to poor or no response to aerosol therapy or due to a lack of collaboration. Two patients developed complications not related to aerosol therapy (tympanic perforation and cholesteatoma pearl). Conclusion: The efficacy of aerosol therapy is comparable to that obtained with classic treatments. We have found no differences in the outcomes obtained in the group previously treated with surgery. We found no indicators of poor response in those patients where the treatment failed (AU)

Displasia fibrosa monostótica de seno frontal. A propósito de un caso / Fibrous monostotic dysplasia of frontal sinus. About a case

La displasia fibrosa es una lesión ósea benigna poco frecuente en la que el hueso sano es sustituido por tejido fibro-óseo desestructurado. Su etiología es desconocida, raramente produce síntomas y el diagnóstico se realiza mediante la clínica, radiología y el estudio histológico. El tratamiento debe reservarse a los casos que producen síntomas y en éstos el tratamiento es quirúrgico (AU)