Effects of cricothyroid muscle asymmetry on vocal fold vibration : experimental study

Orientador: Agricio Nubiato CrespoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de de Ciencias MedicasResumo: Estudos experimentais tem sido de grande utilidade para a compreensão da fisiologia da vibração das pregas vocais e seus mecanismos de compensação, em especial os estudos com situações de assimetria. A situação clínica de assimetria de tensão das pregas vocais tem sido particularmente enfocada nos últimos anos em decorrência de sua sintomatologia sutil e de uma incidência crescente após disseminação do uso da eletromiografia de laringe na prática diária dos otorrinolaringologistas. O objetivo deste estudo foi de descrever e analisar o padrão vibratório das pregas vocais em situação de assimetria causada pela simulação da ação unilateral do músculo cricotireóideo, que leva a uma assimetria de tensão das pregas vocais. O estudo foi desenvolvido em laringes excisadas e o padrão vibratório foi avaliado por meio de eletroglotografia e a optorreflectometria. A optoreflectometria consiste em método de análise do deslocamento vertical, individual de cada prega vocal. Para cada experimento as pregas vocais eram submetidas a fluxos aéreos crescentes e, dados referentes à pressão subglótica, freqüência fundamental de vibração das pregas vocais e o sinal elétrico produzido pelo eletroglotógrafo e pelos dois optorreflectômetros eram coletados. A análise dos dados se baseou no estudo descritivo qualitativo e quantitativo das curvas de vibração das duas pregas vocais e dos espectros extraídos a partir do eletroglotógrafo e cada optorreflectômetro. Os movimentos vibratórios das pregas vocais foram periódicos, no entanto, houve uma diferença de fase entre as pregas vocais em todos os experimentos. A freqüência fundamental foi a mesma para ambas as pregas vocais em cada etapa de variação do fluxo aéreo. Observou-se a presença de subharmônicos e bifonação em todos os experimentos. A prega vocal não tensionada apresentou maior variabilidade espectral com a variação do fluxo aéreo do que a prega vocal tensionadaAbstract: Experimental studies have been of great use in the comprehension of vocal fold physiology and its compensatory mechanisms. Studies of asymmetric conditions of the larynx have been of particular interest for these purposes. The clinical condition of vocal fold tension asymmetry has been increasingly reported in the past years. This is probably due to its subtle clinical presentation in contrast to the increasing number of diagnosis being made after the growing knowledge and use of laryngeal electromyography. The purpose of this study was to describe and analyze the vibratory pattern of the vocal folds in an asymmetric condition. Asymmetry was caused by simulation of the unilateral action of the cricothyroid muscle that leads to tension asymmetry of the vocal folds. The experiments were performed on excised larynges. Electroglotography and optoreflectometry were used to evaluate vocal fold vibration. Optoreflectometry analyzed vertical displacement of each vocal fold, separately. For each larynx vocal fold vibration was observed under increasing airflow. At each air flow variation data regarding, subglottic pressure, fundamental frequency of vibration and signals produced by electroglotography and both optoreflectometers were registered for posterior analysis. Data analysis consisted on a qualitative and quantitative description of the curves of vibration. Power spectrums were used for detailed analysis of spectral formation, identification of harmonics and signal perturbations. Vibratory movements of the vocal folds were periodic. A phase shift was found on all experiments. Fundamental frequency was the same for both vocal folds under the same airflow. Subharmonics and biphonation were observed on all experiments. The lax vocal fold showed greater spectral variation with increasing airflow than the tense vocal foldMestradoCiencias BiomedicasMestre em Ciências Médica

[balloon Laryngoplasty For Acquired Subglottic Stenosis In Children: Predictive Factors For Success].

The treatment of subglottic stenosis in children remains a challenge for the otorhinolaryngologist, and may involve both endoscopic and open surgery. To report the experience of two tertiary facilities in the treatment of acquired subglottic stenosis in children with balloon laryngoplasty, and to identify predictive factors for success of the technique and its complications. Descriptive, prospective study of children diagnosed with acquired subglottic stenosis and submitted to balloon laryngoplasty as primary treatment. Balloon laryngoplasty was performed in 37 children with an average age of 22.5 months; 24 presented chronic subglottic stenosis and 13 acute subglottic stenosis. Success rates were 100% for acute subglottic stenosis and 32% for chronic subglottic stenosis. Success was significantly associated with acute stenosis, initial grade of stenosis, children of a smaller age, and the absence of tracheostomy. Transitory dysphagia was the only complication observed in three children. Balloon laryngoplasty may be considered the first line of treatment for acquired subglottic stenosis. In acute cases, the success rate is 100%, and although the results are less promising in chronic cases, complications are not significant and the possibility of open surgery remains without prejudice

Histologic comparison of vocal fold microflap healing by second intention, with sutures and glue in rabbits

Orientador: Agrício Nubiato CrespoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências MédicasResumo: Alterações benignas das pregas vocais são causas importantes de disfonia e compreendem parte significativa dos casos atendidos pelo otorrinolaringologista na prática diária. Nas últimas décadas diversas técnicas foram descritas para o tratamento cirúrgico destas lesões, com sucesso variável. Para uma excelente qualidade vocal é necessária a preservação do complexo movimento ondulatório da superfície das pregas vocais. A presença de cicatriz nas pregas vocais pode comprometer o resultado da cirurgia e constitui hoje um dos principais desafios da fonocirurgia. Existem inúmeros tratamentos das cicatrizes das pregas vocais e, ainda hoje, com resultados bastante insatisfatórios. Diversos autores têm estudado o processo cicatricial procurando meios de intervir para interromper a produção de substâncias que alterem definitivamente as propriedades vibratórias das pregas vocais. Laringologistas com grandes séries de pacientes tratados cirurgicamente descrevem resultados excelentes com uma ou outra variação de suas técnicas cirúrgicas. Faltam, no entanto, estudos controlados que confirmem o melhor efeito de uma técnica sobre outra. Relatos clínicos tendem a favorecer uma ou outra técnica conforme a experiência e formação do cirurgião, disponibilidade de material e instrumental cirúrgico. Existem divergências quanto à necessidade de fechamento da incisão por meio de sutura, utilização de cola de fibrina ou permitir que a reepitelização ocorra por segunda intenção. Objetivo: Comparar os aspectos cicatriciais resultantes da técnica de microflap das pregas vocais quando utilizadas cola de fibrina, sutura e cicatrização por segunda intenção. Material e Métodos: Realizou-se estudo experimental em coelhos comparando as técnicas: microflap, microflap e seu fechamento com sutura e microflap e seu fechamento com cola de fibrina com o objetivo de avaliar os efeitos de cada técnica na cicatrização das pregas vocais. A cicatrização foi avaliada histologicamente em três tempos pós-operatórios: sete dias, trinta dias e três meses. Avaliou-se a concentração de colágeno, presença de células inflamatórias, espessuras do epitélio e da lâmina própria. Resultados: As três técnicas provocaram um aumento significativo na concentração de colágeno em comparação com grupo controle normal, não operado. A cicatrização por segunda intenção provocou menor concentração de colágeno aos 90 dias. Todas as técnicas apresentaram aumento significativo da espessura epitelial uma semana após as intervenções. O grupo submetido a sutura atingiu níveis semelhantes ao do grupo controle após 90 dias. Após sete dias a espessura da lâmina própria obteve valores próximos aos normais com todas as técnicas. Após 90 dias apenas o grupo submetido a confecção do microflap e uso de cola manteve espessura semelhante ao grupo controle, todos os outros tiveram uma significativa redução da espessura. O número de células inflamatórias aumentou significativamente com todas as técnicas exceto nas pregas vocais submetidas a microflap e cola após 30 dias e, também, nas pregas vocais submetidas à microflap e sutura após 90 dias. Conclusão: Apesar do uso da cola de fibrina e suturas em microfonocirurgia serem seguros e resultar em bons resultados conforme relatados por outros autores, ainda não há evidência científica que justifique seu usoAbstract: Benign lesions of the vocal cords are an important cause of dysphonia and represent a significant number of patients attended by the otolaryngologist specialist. Several techniques have been described for the surgical treatment of these lesions with variable outcome. Satisfactory vocal quality is imperative when considering a good or bad surgical outcome. To achieve satisfactory vocal quality the complex vibratory movement of the vocal folds must be preserved and kept at its best. Scarring of the vocal folds may compromise vocal outcome and this is the main challenge in microphonosurgery nowadays. Several treatments have been described to solve the problem of scar formation on the vocal folds. Nevertheless, satisfactory long-term vocal quality has been described as quite disappointing. Studies have focused on the early stages of the scarring process of the vocal cords and on the refinement of surgical techniques to prevent or minimize scar formation. There is, a lack of studies comparing surgical techniques and their impact on scar formation. Clinical reports tend to favor one or other technique but these vary depending on the surgeons personal experience and training, instrumentation and material availability. There is a consensus on the need of maximum preservation of the epithelium and superficial lamina propria and minimal exposure of vocal ligament. On the other hand the need of microsuture or glue to cover the wound is controversial. Objective: To compare scarring characteristics of microflap in vocal folds when left to heal by second intention and when the defect was closed with sutures or fibrin glue. Material and methods: A comparative experimental study comparing the microflap technique alone, microflap with microsuture and microflap with fibrin glue was carried out. The experiments were performed out on a rabbit model to evaluate the effects of each technique on vocal cord healing and scar formation. Healing was evaluated histologically one week, 30 and 90 days after surgical intervention. Scar formation was evaluated based on: collagen concentration, inflammatory cell infiltration, epithelium and lamina propria thickness. Results: A significant increase in collagen concentration was observed with all three techniques when compared to normal control vocal folds. Vocal folds submitted to microflap alone presented the smallest values for collagen concentration at 90 days. Conclusion: All techniques showed significant increase in epithelium thickness one week after the procedures. At 90 days epithelium thickness had decreased in all techniques but reached values similar to control vocal folds only in the suture group. Lamina propria thickness was similar to the control group in all groups after one week, after 90 days only the fibrin glue group was not significantly different from the control group. Inflammatory cells where significantly increased in all groups except for the suture group at 90 days. Although the use of sutures and glue is safe and can produce good vocal results as reported by experienced surgeons there remains to be no evidence consistently justifying its use in microphonosurgeryDoutoradoOtorrinolaringologiaDoutora em Ciências Médica

Pegylated interferon for treating severe recurrent respiratory papillomatosis in a child: case report

ABSTRACT CONTEXT: Recurrent respiratory papillomatosis (RRP) is the most common laryngeal tumor. During childhood, it may present in extremely severe forms defined by the need for frequent surgical procedures to relieve respiratory distress and/or involvement of extralaryngeal sites such as lung involvement. Adjuvant therapies are indicated in these cases and interferon is one of the options. Pegylated interferon is more effective than conventional alpha interferon and, given its reported results in relation to treating hepatitis C over the past decade, we hypothesized that this might be more effective than conventional interferon also for treating respiratory papillomatosis. Use of a treatment strategy that eliminates the need for general anesthesia is particularly appealing, yet obtaining approval for use of medications that are not currently used for this purpose is challenging. CASE REPORT: We report the case of a child with severe RRP that had been followed for the preceding six years, who was treated with pegylated interferon after failure of other adjuvant therapies. There was noticeable improvement in the frequency of surgical procedures, which was regarded very receptively, considering the child’s history and previous response to other therapies. CONCLUSION: Pegylated interferon may be a good option for diminishing the need for surgical intervention in severe cases of recurrent respiratory papillomatosis

Predicting Outcomes Of Balloon Laryngoplasty In Children With Subglottic Stenosis.

The treatment of subglottic stenosis in children remains a challenge for the otolaryngologist and may involve procedures such as endoscopy, open surgery, and often both. In the recent past, high-pressure balloons have been used in endoscopic treatment due to their relative facility and high success rates. To report success rates in the treatment of acquired subglottic stenosis with balloon laryngoplasty in children and identify predictive factors for the success of the technique and its complications. Descriptive, prospective study of children who were diagnosed with acquired subglottic stenosis and underwent balloon laryngoplasty as the primary treatment. Balloon laryngoplasty was performed in 48 children with an average age of 20.7 months: 31 presented with chronic subglottic stenosis and 17 with acute stenosis. Success rate was 100% for acute and 39% for chronic subglottic stenosis. Success was significantly associated with several factors, including recently acquired stenosis, initial grade of stenosis, younger patient age, and the absence of tracheotomy. Complications were transitory dysphagia observed in three children and a submucosal cyst in one of the patients. Balloon laryngoplasty may be considered as a first line of treatment for acquired subglottic stenosis. In acute cases, the success rate was 100%, and even though results are less promising in chronic cases, complications were not significant and the patients can undergo open surgery without contraindications. Predictive factors of success were acute stenosis, less severe grades of stenosis, younger patient age, and the absence of tracheotomy.79532-

Changes in host-parasitoid food web structure with elevation

Gradients in elevation are increasingly used to investigate how species respond to changes in local climatic conditions. Whilst many studies have shown elevational patterns in species richness and turnover, little is known about how food web structure is affected by elevation.Contrasting responses of predator and prey species to elevation may lead to changes in food web structure. We investigated how the quantitative structure of a herbivore‐parasitoid food web changes with elevation in an Australian subtropical rain forest.On four occasions, spread over 1 year, we hand‐collected leaf miners at twelve sites, along three elevational gradients (between 493 m and 1159 m a.s.l). A total of 5030 insects, including 603 parasitoids, were reared, and summary food webs were created for each site. We also carried out a replicated manipulative experiment by translocating an abundant leaf‐mining weevil Platynotocis sp., which largely escaped parasitism at high elevations (≥900 m a.s.l.), to lower, warmer elevations, to test if it would experience higher parasitism pressure.We found strong evidence that the environmental change that occurs with increasing elevation affects food web structure. Quantitative measures of generality, vulnerability and interaction evenness decreased significantly with increasing elevation (and decreasing temperature), whilst elevation did not have a significant effect on connectance. Mined plant composition also had a significant effect on generality and vulnerability, but not on interaction evenness. Several relatively abundant species of leaf miner appeared to escape parasitism at higher elevations, but contrary to our prediction, Platynotocis sp. did not experience greater levels of parasitism when translocated to lower elevations.Our study indicates that leaf‐mining herbivores and their parasitoids respond differently to environmental conditions imposed by elevation, thus producing structural changes in their food webs. Increasing temperatures and changes in vegetation communities that are likely to result from climate change may have a restructuring effect on host–parasitoid food webs. Our translocation experiment, however, indicated that leaf miners currently escaping parasitism at high elevations may not automatically experience higher parasitism under warmer conditions and future changes in food web structure may depend on the ability of parasitoids to adapt to novel hosts

Post-extubation laryngitis in children: diagnosis, management and follow-up

Objectives: To describe the occurrence of post-extubation laryngitis, analyze its one-year evolution, and correlate laryngeal lesions with clinical outcomes. Methods: Retrospective study including children up to 13 years old at a tertiary hospital between March 2020 and March 2022 with diagnosis of post-extubation laryngitis confirmed by endoscopic examination. Exclusion criteria were prior history of intubation or anatomical airway abnormalities. Medical records were reviewed to characterize patients, underlying diagnosis, laryngeal lesions, treatment, and outcomes at 12-month follow-up. Results: The study included 38 endoscopically confirmed post-extubation laryngitis cases, corresponding to 86.4% of suspected cases. The mean age was 13.24 months, and 60.5% were male. Acute respiratory failure was the leading cause of intubation. Initial treatment was clinical, and initial diagnosis was defined by nasopharynoglaryngoscopy and/or Microlaryngoscopy and Bronchoscopy (MLB) findings. Initial diagnostic MLB was performed in 65.7% of the patients. Approximately half (53%) of the patients exhibited moderate or severe laryngeal lesions. When compared to mild cases, these patients experienced a higher rate of extubation failures (mean of 1.95 vs. 0.72, p = 0.0013), underwent more endoscopic procedures, and faced worse outcomes, such as the increased need for tracheostomy (p = 0.0001) and the development of laryngeal stenosis (p = 0.0450). Tracheostomy was performed in 14 (36.8%) children. Patients undergoing tracheostomy presented more extubation failures and longer intubation periods. Eight (21%) developed laryngeal stenosis, and 17 (58.6%) had complete resolution on follow-up. Conclusion: Post-extubation laryngitis is a frequent diagnosis among patients with clinical symptoms or failed extubation. The severity of laryngeal lesions was linked to a less favorable prognosis observed at one-year follow-up. Otolaryngological evaluation, follow-up protocols, and increased access to therapeutic resources are essential to manage these children properly. Level of evidence: Level 4