Discussion

The incidence of the tympanosclerosis in ears with chronic middle-ear infection varies between 3 per cent and 43 per cent in the literature.^{Reference da Costa, Paparella, Schachern, Yoon and Kimberley7–Reference Emmet and Shea9} In the present series, tympanosclerosis was present in 32 per cent of the ears with chronic otitis media; 66 per cent of these ears had ossicular chain fixation (a clinically significant finding).

Knowing whether a patient with tympanosclerosis has a stapes fixation is important as this can have implications regarding the surgical results and potential complications. Additionally, stapes mobility is the most crucial factor to influence the hearing results. In one study, the best hearing results were found in patients with an intact ossicular chain and mobile stapes, and the poorest results were found in ears with a fixed stapes without suprastructure.^{Reference Lau and Tos10} Hearing results are better when the stapes is mobile and ossiculoplasty is performed with incus transposition.^{Reference Bayazit, Ozer, Kara, Gokpinar, Kanlikama and Mumbuç11} In ossicular attic fixation, ossicular reconstruction with a partial ossicular replacement prosthesis can give better results than the mobilisation of major ossicles in tympanosclerosis patients.^{Reference Teufert and De La Cruz6}

We considered that some clinical evaluation parameters might be predictive of the ossicular chain status in tympanosclerosis cases. In our clinic, a patient's clinical history (i.e. duration of hearing loss and/or ear discharge, recent ear discharge) is determined by examining the history notes taken in their pre-operative visits. We record and archive consistent data on audiogram charts; we re-review inconsistent data with the patient and record confirmed data. The analyses in this study showed no differences in age or disease duration between ears with chronic otitis media with tympanosclerosis and those with chronic otitis media without tympanosclerosis. However, ears with tympanosclerosis were clinically characterised by the absence of middle-ear suppurations, usually for a long time. In addition, the probability of a mobile stapes (determined during surgery) was higher in ears with tympanosclerosis when there was ear drainage in the year prior to surgery.

These findings show that careful clinical history taking in tympanosclerosis cases can inform the surgeon about ossicular chain status, though the condition of the ossicular chain can only be determined during ear surgery. Anamnesis is always important in disease diagnosis, in addition to imaging and laboratory findings. We could not find any study on the predictive value of computed tomography for ossicular chain mobility. One study investigating the value of pre-operative audiometry reported that hearing loss in ears with an intact ossicular chain is frequency-dependent, and the hearing loss in ears with an immobile ossicular chain is more significant at lower frequencies, preserving better hearing at 2000 Hz.^{Reference Dinç, Damar, Erdem, Eliçora, Akyıldız and Kumbul12}

Tympanosclerosis is characterised histologically by: decreased vascularisation and cell formation, increased hyalinisation, calcium deposition, and the formation of cartilage-like and/or bone-like tissue (secondary to increases in collagen fibrils due to progressive fibroblast infiltration of the connective tissue layer).^{Reference Sorensen and True13,Reference Ferlito14} The long-term absence of ear drainage may be due to widespread sclerosis of middle-ear mucosa. For this reason, the absence of ear drainage in the clinical history of a patient may indicate more extensive involvement of the ear by tympanosclerosis.

In conclusion, tympanosclerosis is characterised by the long-term absence of ear drainage. The clinical history of a patient may reveal valuable information regarding ossicular involvement in tympanosclerosis. The probability of a mobile ossicular chain or a mobile stapes is higher in ears with a clinical history of recent drainage.