## 1 Introduction  
Stapes surgery remains the procedure of choice for hearing rehabilitation in otosclerosis [1], even though this disease was described almost 400 years ago [2] Otosclerosis is a rather common cause of adult conductive hearing loss, with a clinical prevalence estimated at 0.3% to 0.38% [3]. During the stages surgery, the chorda typani (CT) nerve is manipulated, leaving the operated patient with potential consequences. CT is considered as a \"taste nerve\"; however, other functions have also been discovered. The CT nerve is said to be responsible for non-gustatory information such as texture, temperature [4], and pain [5], for conveying the general sensations from the tongue [6] and for having parasympathetic fibers for submandibular and sublingual glands that stimulate salivary flow [5]. In humans, taste receptor cells are found on the tongue, palate, and other parts of the pharynx and epiglottis [7]. They are innervated by the branches of facial, glossopharyngeal and vagal nerves [8]. Taste receptor cells form taste buds that are organized in macroscopically visible structures named papillae. Papillae are named regarding their shape: foliate (can be found on the back lateral sides of the tongue), vallate (the largest among papillae, found on the dorsum of the posterior tongue) and mushroom-shaped fungiform papillae (FP) (located at the first 2/3 of the tongue). FP have complex sensory functions, including responses to chemical, thermal and mechanical stimuli [9]. FP of anterior 2/3 of the tongue are innervated by CT, a branch of the facial nerve [7]. However, according to animal studies, they could be dually innervated, including the trigeminal nerve fibers [10]. As described by [PERSON] et al., 2007 [11], the CT also innervates the contralateral side of the anterior 2/3 of the tongue, explaining the normal taste and FP morphology after ipsilateral CT injury. On the other hand, the number and morphology of papillae are expected to reflect the viability of the appropriate nerve. [PERSON] et al., 2000 [12] reported that neural damage leads to a decrease in the number of papillae. For that reason, the degeneration process of papillae after severing the CT nerve remains unclear [13]. Taste perception is reported to be influenced by the density and morphology of papillae. Consequently, the visualization of FP is essential [14; 15], being the most anatomically accessible. This has been in the focus of scientific interest for many years, yet the techniques have evolved. In vivo techniques allow the visualization of papillae number [12], structure, and vascularization [14]. Some techniques of papillae quantification require the usage of food dye [16]. Very few studies concentrate on postoperative FP morphology [17]. Only one study [18] applies narrow-band imaging (NBI), a noninvasive technique to visualize FP vascular patterns of the anterior 2/3 of the tongue. NBI is a relatively new method of blood vessel visualization that illuminates the structures in narrowed red, green, and blue spectrum bands with interference filters. That increases the contrast between the epithelial surface and the subjacent vascular network [19]. It has been essential in evaluating different organ systems and has an enormous added value in assessing a lesion's malignant potential [20]. To obtain detailed images of epithelium, NBI can be performed with the contact endoscopy technique [21; 22]. The alterations in taste are not the only complaints after the stapes surgery. A tingling sensation and tongue numbness are common postoperative findings. The CT nerve is believed to confer the general sensory fibers to the anterior 2/3 of the tongue. A static two-point discrimination test proved to be a sensitive and specific tool for the tongue general sensation assessment [6]. Although there is a lot of evidence of CT function impairment in relation to stapes surgery, many questions remain unanswered.