# Numerical Study of Tympanosclerosis Including Its Effect on Human Hearing
## 1 Introduction  
Tympanosclerosis is characterized by the calcification of the tissues of the eardrum and middle ear ossicles. When this calcification only involves the eardrum, it is designated as myringosclerosis. Tympanosclerosis, itself, can also invade the malleus, the malleus and incus, or all the tympanic cavity of the middle ear. It is easy to identify a tympanosclerosis due to the typical white and opaque look of the eardrum. The affected area can vary considerably between cases [1]. Tympanosclerosis within the middle ear is similar to that occurring within the eardrum. When it occurs in the middle ear, it often leads to conductive hearing loss, caused by the ossicular fixation. The eardrum can be divided into a \"_pars tensa_\" and \"_pars flacida_\". The \"_pars tensa_\" has three layers. The exterior layer is the epidermis that continues with the external auditory canal. The intermediate layer, the lamina propria, is mainly composed of collagen fibers (responsible for its mobility). The interior layer is the mucosal epithelium, which continues in the middle ear mucosa. Tympanosclerosis develops in the lamina propria. Histologically, tympanosclerosis arises as an acellular hyalilization of the subepithelial connective tissue of the eardrum and the middle ear, with deposition of proteinaceous substances. In most instances, calcification is also present. Tympanosclerosis occurs due to the fact of a degenerative process within the connective tissue. This leads to the degradation of the collagen fibers and originates dystrophic calcification. This degeneration may be a consequence of inflammation or an infection within the middle ear due to the fact of, for example, bacterial proteinases and collagenases. Another possible cause of tympanosclerosis is an autoimmune process [2]. A study by [PERSON] et al. proposed that a correlation exists between the presence of atherosclerosis and tympanosclerosis, where people with atherosclerosis are more prone to having tympanosclerosis [3]. Tympanosclerosis or myringosclerosis can be caused by a prior history of tympanostomy tube placement and/or an associated history of otitis media. Unless the involvement of the eardrum is particularly severe, it is rare for tympanosclerosis to cause significant conductive hearing loss. Tympanosclerosis is a less common pathology than myringosclerosis. Tympanosclerosis frequently develops after an acute or chronic otitis media. Children who have otitis media with effusion and ventilation tubes have a higher risk of developing tympanosclerosis, between 11 and 37% [4; 5]. If the tympanosclerosis is extensive, it may affect hearing. Audiometry tests (tonal and vocal audiograms) should be conducted if there is hearing loss. In the vast majority of cases, the air-bone gap is smaller than 40 dB. Tympanometry produces flattened tympanograms, type B tracing, with a low static admittance due to the increased stiffness of the eardrum [6]. Computerized tomography (CT) can be used to determine if tympanosclerosis exists in the middle ear. In a study by [PERSON] (2006), 35.6% of patients with chronic otitis media, suppurative or not, had tympanosclerosis. In these patients, 77.8% had dry ear and conductive hearing loss [7]. Studies [8; 9] have shown that tympanosclerosis plaques have a concentration of phosphate and calcium, with a Ca/P ratio similar to hydroxyapatite (HA). In the lamina propria, the crystals of carbonate apatite appear dispersed in the matrix of degenerated connective tissue [10]. Tympanoplasty and ossicular reconstruction can be performed in cases of tympanosclerosis. The risks of cochlear damage occur due to the extensive dissection that is required in tympanosclerotic ears and the coexistence of labyrinthine erosion. Treatment is only necessary when hearing loss exists. When only myringosclerosis is present, hearing loss is rare.