Optimal management of Cogan’s syndrome: a multidisciplinary approach

Cogan's syndrome (CS) is a rare disorder characterized by nonsyphilitic interstitial keratitis (IK) and audio-vestibular symptoms. CS affects mainly young Caucasian adults, mostly during their first three decades of age, and may develop into typical and atypical variants. Typical CS manifests primarily with IK and hearing loss, whereas atypical CS usually presents with inflammatory ocular manifestations in association with audio-vestibular symptoms but mostly different Ménière-like symptoms and, more frequently, with systemic inflammation (70%), of which vasculitis is the pathogenic mechanism. CS is considered as an autoimmune- or immune-mediated disease supported mainly by the beneficial response to corticosteroids. Using well-developed assays, antibodies to inner ear antigens, anti-Hsp70, and antineutrophil cytoplasmic antibodies were found to be associated with CS. Corticosteroids represent the first line of treatment, and multiple immunosuppressive drugs have been tried with variable degrees of success. Tumor necrosis factor-alpha blockers and other biological agents are a recent novel therapeutic option in CS. Cochlear implantation is a valuable rescue surgical strategy in cases with severe sensorineural hearing loss unresponsive to intensive and/or innovative immunosuppressive regimens

Nasal manifestations in granulomatosis with polyangiitis: a case report and review of the literature

Granulomatosis with polyangiitis (GPA) is an anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides of medium and small arteries, characterized by necrotizing granulomatous inflammation of the upper and lower respiratory tract with coexist- ing glomerulonephritis. We report a case of GPA in a patient presenting with a six-month history of spontaneous epistaxis, nasal obstruction and frontal headache. Nasal endoscopy showed a large nasal septum perforation and an anterior translucid mass in the right nasal fossa. Findings were confirmed by computed tomography (CT) scan with contrast. The patient underwent func- tional transnasal endoscopic removal of the mass; histological examination showed tissue features suggestive of GPA; dosage of c-ANCA e p-ANCA antibodies confirmed GPA diagnosis. Nasal septum perforation has long been recognized as a feature of GPA, in which granulomatous destruction of nasal cartilage can result in perforation and saddle-nose deformity. Prompt diagno- sis of GPA is important to initiate therapy which may be life-saving and organ sparing

Audio-vestibular symptoms in systemic autoimmune diseases

Immune-mediated inner ear disease can be primary, when the autoimmune response is against the inner ear, or secondary. The latter is characterized by the involvement of the ear in the presence of systemic autoimmune conditions. Sensorineural hearing loss is the most common audiovestibular symptom associated with systemic autoimmune diseases, although conductive hearing impairment may also be present. Hearing loss may present in a sudden, slowly, rapidly progressive or fluctuating form, and is mostly bilateral and asymmetric. Hearing loss shows a good response to corticosteroid therapy that may lead to near-complete hearing restoration. Vestibular symptoms, tinnitus, and aural fullness can be found in patients with systemic autoimmune diseases; they often mimic primary inner ear disorders such as Menière’s disease and mainly affect both ears simultaneously. Awareness of inner ear involvement in systemic autoimmune diseases is essential for the good response shown to appropriate treatment. However, it is often misdiagnosed due to variable clinical presentation, limited knowledge, sparse evidence, and lack of specific diagnostic tests. The aim of this review is to analyse available evidence, often only reported in the form of case reports due to the rarity of some of these conditions, of the different clinical presentations of audiological and vestibular symptoms in systemic autoimmune diseases

Circuit Modeling of Discontinuous Planar Waveguides at High Frequencies

We present an accurate theoretical approach in view to design discontinuous optical waveguides at high frequencies. The model is based on the Floquet's theory and on the variational equivalent circuit. The distributed circuit model is developed through the use of the microwave network the- ory and the optical theory of the step discontinuities. This accurate approach considers dielectric periodic structures with high dielectric contrast and the transmission line model applied to guided modes of a discontinuous slab waveguide

Bragg reflector by means of the form birefringence effect in dielectric rings

Abstract In this work, form birefringence physics and the mechanisms of Si/SiO2 dielectric concentric optical rings are investigated. The optical rings are modeled by means of a Bragg reflector. Similarly to a negative uniaxial crystal, the dielectric concentric pattern admits two preferred propagation directions defined by an extraordinary and an ordinary refractive index representing two field polarizations. The circular grating profile splits the electromagnetic field into a radial (extraordinary field) and a tangential (ordinary field) component which represent two modes of the periodic structure. These two modes are characterized by the refractive index ellipse obtained by the Huygens principle. The model is developed through the wave front propagation inside the anisotropic structure. The Bragg theory and conservation of momentum vectors provide the Bragg angles of the ordinary and extraordinary rays for different optical wavelengths. The Bragg theoretical model is validated by the finite difference time domain (FDTD) approach for a wavelength of λ = 0.98 μ m

Transverse Resonance Circuit Modeling and Hertzian Potential Formulation for Integrated Optical Waveguides

In this work we present a new efficient numerical simulator based on the concepts of transverse resonance and electromagnetic Hertzian potentials. The method includes the transverse resonance circuit modelling (TRCM) well suited with scalar time-domain Hertzian potential modelling (HPM). The transverse circuit provides the effective refractive indices related to the guided modes of an optical waveguide. The simultaneous implementation of the TRCM and HPM approaches provides an accurate time domain electromagnetic field solution for two-dimensional and three-dimensional optical waveguides

Double grating design of 3D phase matched waveguide for second harmonic χ(2) process

Theoretical analysis on second harmonic (SH) generation with phase matched grating in waveguide is presented from the viewpoint of device design. Usually high intensity sources are necessary in order to observe a SH in a χ (2) nonlinear structure. For this purpose, the novel proposed design takes into account a double grating effect which enhances the guided SH signal along the waveguide. In the presented structure two grating are considered: the first grating, considered at the interface between air and core, is designed in order to obtain an efficient SH conversion process by considering the quasi phase matching (QPM) condition; the second grating, placed at the interface between the core and the substrate region, increases the SH power along the propagation direction through the coupling with the substrate modes generated by the diffraction effect. The novelty of this work is in the combined effect of the two gratings. The grating lengths and periods are designed by considering the nonlinear coupled mode theory with the effective dielectric constant (EDC) assumption. The analysis includes three dimensional (3D) cases where phase matching is involved, in particular the model is applied to a GaAs/AlGAs waveguides with fundamental wavelength at λ FU =1.55 μm and SH signal at λ SH =0.775 μm

Near Field and Optical Diffraction of 3D Dielectric Corner by Transmission Line Modeling and Multipole Expansion of Green's Function

We propose a novel modeling of the dielectric cubic corner, that is suitable for inclusion in a standard electromagnetic (EM) simulator. The model starts from a consideration of the equivalent current densities on the cube facets. It proceeds by employing a classical multipole expansion of the Green's function at the corner and introduces the novel principle of Simultaneous Transverse Resonance Diffraction (STRD) in order to determine the singularity of the EM field. The novel STRD approach considers the analogy between the EM field in proximity of the 90 deg. dielectric corner and resonant transmission lines. We combined the analytical and the numerical approaches in order to obtain an efficient numerical procedure. The theory is validated by standard finite element method (FEM) simulation, yielding information about the accuracy of the near field around the dielectric corner