205 research outputs found

    Nonequilibrium, thermostats and thermodynamic limit

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    The relation between thermostats of "isoenergetic" and "frictionless" kind is studied and their equivalence in the thermodynamic limit is proved in space dimension d=1,2d=1,2 and, for special geometries, d=3d=3.Comment: 22 pages PRA 2-columns format v3: Typos corrected as acknowledge

    Current reservoirs in the simple exclusion process

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    We consider the symmetric simple exclusion process in the interval [−N,N][-N,N] with additional birth and death processes respectively on (N−K,N](N-K,N], K>0K>0, and [−N,−N+K)[-N,-N+K). The exclusion is speeded up by a factor N2N^2, births and deaths by a factor NN. Assuming propagation of chaos (a property proved in a companion paper "Truncated correlations in the stirring process with births and deaths") we prove convergence in the limit N→∞N\to \infty to the linear heat equation with Dirichlet condition on the boundaries; the boundary conditions however are not known a priori, they are obtained by solving a non linear equation. The model simulates mass transport with current reservoirs at the boundaries and the Fourier law is proved to hold

    Surgical multidisciplinary approach of orbital complications of sinonasal inflammatory disorders

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    Orbital infection complicating sinonasal inflammatory disorders may lead to serious sequelae, including blindness and death, if untreated. Communication between the otorhinolaryngologist, neuroradiologist, ophtalmologist, neurosurgeon and maxillo-facial surgeon is critical and time-sensitive for a successful treatment. The large majority of pre-septal cellulitis cases resolves after broad-spectrum antibiotic therapy. Also orbital cellulitis has been found responsive to pharmacological approach in most cases. The management of the subperiosteal abscess (SPA) is more controversial. An aggressive surgical approach is always recommended also in case of cavernous sinus thrombosis. In cases of surgical indication, debate is still open on the timing and the approach (endoscopic or external). The surgeon should be prepared to convert an endoscopic approach to an external one if needed and this should be included in the informed consent. Decompression of one or more orbital walls may be necessary if orbital pressure remains elevated. Immediate surgery is indicated in children with large SPA or orbital abscesses (OA), or in immune-compromised patients. Moreover, any worsening in the ophthalmological function must be carefully considered as a landmark in candidacy to surgery

    Transnasal endoscopic removal of malformation of the odontoid process in a patient with type I Arnold-Chiari malformation: a case report

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    The endoscopic endonasal approach is emerging as a feasible alternative to the trans-oral route for the resection of the odontoid process, when the latter produces a compression of the brainstem and cervicomedullary junction. This type of approach has some advantages, such as excellent pre-vertebral exposure of the cranio-vertebral junction in patients with small oral cavities and the possibility to avoid the use of mouth retractors. A typical case of a 24-year-old male patient with a previous diagnosis of type I Arnold-Chiari Malformation, suffering from a posterior dislocation of the odontoid process causing severe anterior compression of the brainstem, is presented to stress the potential of this technique. Trans-nasal endoscopic removal of the odontoid process was performed and resolution of the ventral compression of the brainstem was achieved. This report demonstrates that in selected cases, an endoscopic endonasal approach should now be considered an excellent alternative to the traditional trans-oral approach

    Complications in endoscopic ear surgery

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    Objective: The aim of this study was to examine the premise that endoscopic ear surgery (EES) is associated with a low rate of complications (intraoperative and postoperative). Study design: Retrospective review at two institutions. Setting: Tertiary referral center. Patients: The study included 825 patients who underwent exclusive EES between 2008 and 2016 at the Otorhinolaryngology-Head and Neck Surgery Department of Modena University Hospital, and between 2014 and 2016 at the Otorhinolaryngology-Head and Neck Surgery Department of Verona University Hospital. Interventions: Exclusive endoscopic ear surgery between 2008 and 2016 (tympanoplasties, second look or revision tympanoplasties, myringoplasties, stapedoplasties, canalplasties, ossiculoplasties, and exploratory tympanotomies). All surgical procedures were performed by two experienced surgeons. Main outcome measure: For each procedure, intraoperative, and early and delayed postoperative complications were evaluated. Results: The most common ear pathologies for which patients were sent for EES were cholesteatoma (33.6%), chronic otitis media (36.3%) and otosclerosis (26.8%). There was no case of major intraoperative complications such as injury to the dura or vascular structures. We observed minor intraoperative complications in 4.1% of the cases. Only 1.3% of patients experienced early postoperative complications. Delayed complications affected less than 1% of the cohort. Conclusions: Data from this study confirm the safety of the endoscopic technique, with very low complication rates, indicating that EES is a reliable therapeutic option, in particular, for tympanoplasties, myringoplasties, and stapedoplasties, as well as second look procedures. We have reported our experience with EES morbidity so that it can be compared with data from other centers using the same surgical technique

    Exclusive endoscopic transcanal transpromontorial approach: a new perspective for internal auditory canal vestibular schwannoma treatment

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    OBJECTIVE The aim of this study was to describe the first case series in which an exclusive endoscopic transcanal transpromontorial approach (EETTA) was used to treat small vestibular schwannomas (VSs) and meningiomas of the internal auditory canal (IAC). METHODS The authors performed a retrospective review of patients who had undergone surgery using an EETTA to the IAC at 2 university tertiary care referral centers during the period from November 2011 to January 2015. RESULTS Ten patients underwent surgery via an EETTA for the treatment of VS in the IAC at the University Hospital of Modena or the University Hospital of Verona. The patients had Koos Grade I or II tumors and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Class D hearing status preoperatively. Gross-total resection was achieved in all patients. No major complications such as cerebrospinal fluid leakage or hemorrhage were reported. In 7 of 10 (70%) patients, facial nerve function was normal immediately after surgery (Rough Grading System [RGS] Grade I). Two patients presented with a transitory facial palsy immediately after surgery (RGS Grade II-III) but experienced complete recovery during the follow-up period. The mean follow-up was 10 months. CONCLUSIONS The EETTA proved to be successful for the removal of VS or meningioma involving the cochlea, fundus, and IAC, with possible lower complication rates and less invasive procedures than those for traditional microscopic approaches. The potential for the extensive and routine use of this approach in lateral and posterior skull base surgery will depend on the development of technology and surgical refinements and on the diffusion of skull base endoscopic skills among the otolaryngological and neurosurgical communities

    Validation of the Modena bleeding score in endoscopic sinus surgery

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    Introduction: The Modena bleeding score is a categorical rating scale that allows the assessment of the surgical field in relation to bleeding during endoscopic surgery. It has recently been presented and validated in the field of endoscopic ear surgery by the present authors. The Modena bleeding score provides five grades for rating the surgical field during endoscopic procedures (from grade 1 − no bleeding to grade 5 − bleeding that prevents every surgical procedure except those dedicated to bleeding control). Objective: The aim of this study was to validate the Modena bleeding score in the setting of endoscopic sinus surgery. Methods: Fifteen three-minute videos of endoscopic sinus surgery procedures (each containing three bleeding situations) were evaluated by 15 specialists, using the Modena bleeding score. Intra and inter-rater reliability were assessed, and the clinical validity of the Modena bleeding score was calculated using a referent standard. Results: The data analysis showed an intra-rater reliability ranging from 0.6336 to 0.861. The inter-rater reliability ranged from 0.676 to 0.844. The clinical validity was α = 0.70; confidence limits: 0.64 − 0.75, corresponding to substantial agreement. Conclusion: The Modena bleeding score is an effective method to score bleeding during endoscopic sinus surgery. Its application in future research could facilitate the performance and efficacy assessment of surgical techniques, materials or devices aimed to bleeding control during endoscopic sinus surgery

    Salvage neck dissection for isolated neck recurrences in head and neck tumors: Intra and postoperative complications

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    Background and Objectives: The current evidence regarding complications after salvage neck dissection (ND) for isolated regional recurrences (IRRs) in head and neck cancers is poor. The aim of this study is to evaluate the incidence and differences in complication rates of salvage ND after primary surgery, radiotherapy, chemoradiotherapy, or combined treatments. Methods: This was a multicentric retrospective study on 64 patients who underwent salvage ND for IRR in three Italian institutes between 2008 and May 2020. Results: Complications were detected in 7 of the 34 patients (20.8%) and surgeons described difficult dissection in 20 patients (58.82%). Accidental vascular ligations or nervous injury during surgery were never detected. None of the variables analyzed were statistically significant in predicting the risk of complications, disease-free survival, or overall survival. Conclusions: IRR represents a rare entity among total relapses. The incidence of complications after salvage ND for IRR is higher than after primary surgery but at an acceptable rate in experienced hands. However, an adequate balance between functional and oncological outcomes is mandatory
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