ABSTRACT
Abstract Introduction Grossly displaced membranes are characteristic of endolymphatic hydrops. The process whereby physiological membrane displacement becomes pathological may be mediated by stress, but the membrane biomechanics underlying this transition are unclear. Objective This study seeks to determine the role of suspensory tethers during pressure-induced membrane displacement in the generation of the membranous lesions seen in this disease entity using a biomechanical model approach. Methods The location of membrane suspensory tethers was identified histologically. The influence of tethers on model membrane configuration during displacement was assessed graphically. The relationship of membrane configuration during displacement to curvature radius was quantified trigonometrically. The relationship of curvature radius to stress susceptibility was determined mathematically. The net effect of suspensory tethers on membrane stress levels for various degrees of membrane distention and displacement was then calculated numerically. Results In the inferior labyrinth, suspensory tethers are found to occur on the membranes' boundaries. Such tethering is found to impose a biphasic effect on membrane curvature with increasing degrees of displacement. As a consequence, tensile stress susceptibility is found to decline with initial membrane displacement to a critical point nadir beyond which stress then increases monotonically. No such effect was found for the superior labyrinth. Conclusion Boundary tethers in the inferior labyrinth are associated with significant tensile stress reductions until a critical point of membrane displacement is reached. Displacements short of the critical pointmay be physiological and even reversible,whereas such displacements beyond the critical point are apt to be overtly hydropic and irreversible.
Subject(s)
Humans , Tympanic Membrane Perforation/physiopathology , Endolymphatic Hydrops/physiopathology , Stress, Mechanical , Biomechanical Phenomena , Cochlea/physiopathology , Flexural Strength/physiology , Ear, Inner/physiopathologyABSTRACT
OBJECTIVES@#To study the case characteristics of forensic medical identification of traumatic tympanic membrane perforations, and to discuss the key points of forensic medical identification and evaluations methods for tympanic membrane perforations.@*METHODS@#Twenty-four cases of traumatic tympanic membrane perforations accepted by the Academy of Forensic Science during 2017 were retrospectively analysed. The data of perforation size, form, predilection site, healing time and healing mode were evaluated.@*RESULTS@#For the traumatic tympanic membrane perforations, the study showed that the small size of perforation （<1/2 quadrant） with irregular shape was common. The location of perforations was almost on the anterior and inferior quadrant, and centripetal migration healing was common. The healing rate within 6 weeks was up to 90%.@*CONCLUSIONS@#In the identification cases of traumatic tympanic membrane perforations, the key is to determine whether it is traumatic and whether it will heal spontaneously within 6 weeks. It is suggested to check the tympanic membrane weekly by an otic endoscope combined with acoustic impedance measurement at the sixth week, which can improve the accuracy, objectivity and scientificity of the identification.
Subject(s)
Humans , Retrospective Studies , Tympanic Membrane/injuries , Tympanic Membrane Perforation/physiopathology , Wound Healing/physiologyABSTRACT
Response inversion during warm air stimulation is the most controversial finding seen in caloric tests of individuals with tympanic membrane perforation. In such cases, very few studies explore the possible interferences found in the caloric test, bringing about controversies in the interpretation of test results. AIM: This paper aimed at analyzing warm air stimulation effects in individuals with tympanic membrane perforation in comparison with normal healthy controls. MATERIALS AND METHODS: Prospective, non-randomized study in which 48 individuals without vestibular complaints were assessed, 33 had one tympanic membrane perforated and 15 had no ear drum alteration. RESULTS: 39.39 percent of the individuals had response inversion found during the warm air test. In the absence of this phenomenon, nystagmus responses were symmetrical. CONCLUSION: Nystagmus responses to the caloric test in individuals with tympanic membrane perforation were similar to those from healthy controls, with the exception of the fact that they had inverted responses in the warm caloric test.
A inversão de respostas durante a estimulação a ar quente é o achado mais controverso que aparece na prova calórica de indivíduos com perfuração da membrana timpânica. Nestes casos, poucos estudos exploraram as possíveis interferências nos achados da prova calórica, trazendo controvérsias de interpretação no resultado do exame. OBJETIVO: Este trabalho teve o objetivo de analisar a estimulação calórica a ar em indivíduos com perfuração da membrana timpânica em comparação com indivíduos hígidos, sem esta alteração. MATERIAL E MÉTODO: Estudo prospectivo, não-randomizado, no qual foram avaliados 48 indivíduos sem queixas vestibulares, sendo 33 indivíduos com membrana timpânica perfurada unilateralmente e 15 indivíduos sem nenhuma alteração na membrana timpânica. RESULTADOS: 39,39 por cento dos indivíduos apresentaram inversão de respostas na prova calórica a ar quente. Na ausência deste fenômeno as respostas das nistágmicas foram simétricas. CONCLUSÃO: As respostas nistágmicas na prova calórica em indivíduos com perfuração da membrana timpânica foram similares aos indivíduos hígidos, com exceção da presença de inversão de respostas na prova calórica quente.