The Effect of Anatomic Clearance Between Tongue

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Jan 15, 2014 - DOI 10.1007/s12078-014-9162-7. The Effect of Anatomic Clearance Between. Tongue and Soft Palate on Retronasal. Olfactory Function.
The Effect of Anatomic Clearance Between Tongue and Soft Palate on Retronasal Olfactory Function Aytug Altundag, Murat Salihoglu, Melih Cayonu, Hakan Tekeli & Gurkan Kayabasoglu Chemosensory Perception ISSN 1936-5802 Volume 7 Number 1 Chem. Percept. (2014) 7:40-45 DOI 10.1007/s12078-014-9162-7

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Author's personal copy Chem. Percept. (2014) 7:40–45 DOI 10.1007/s12078-014-9162-7

The Effect of Anatomic Clearance Between Tongue and Soft Palate on Retronasal Olfactory Function Aytug Altundag & Murat Salihoglu & Melih Cayonu & Hakan Tekeli & Gurkan Kayabasoglu

Received: 8 September 2013 / Accepted: 5 January 2014 / Published online: 15 January 2014 # Springer Science+Business Media New York 2014

Abstract Research shows that odorants travel to the olfactory receptors by two routes. Oral conditions, mouth movements, mastication, and swallowing are known to influence the perception of retronasal stimuli. The dimension of the anatomical clearance between the soft palate and tongue might affect the retronasal olfaction because retronasal olfaction is only possible when the soft palate–tongue barrier is opened. Therefore, in this present study, our aim is to evaluate the effect of the anatomical clearance between tongue and soft palate on retronasal olfactory function. After rating the mallampati score for the classification of the clearance between tongue and soft palate, the “Sniffin’ Sticks” test for orthonasal olfaction and retronasal olfactory testing were performed. The study was carried out on 276 subjects, and the mean age of the participants was 27 years ranging from 19 to 53 years. The participants were divided into two groups: Group 1 included participants with mallampati Class 1 and 2 scores; Group 2 included participants with mallampati Class 3 and 4 scores. A. Altundag (*) Division of Otorhinolaryngology, Istanbul Surgery Hospital, Istanbul 34365, Sisli, Turkey e-mail: [email protected] M. Salihoglu Department of Otorhinolaryngology, Gulhane Military Medicine Academy Haydarpaşa Training Hospital, Uskudar, Istanbul 34668, Turkey M. Cayonu Department of Otorhinolaryngology, Amasya University Training and Research Hospital, Amasya 05100, Turkey H. Tekeli Department of Neurology, Gulhane Military Medicine Academy Haydarpasa Training Hospital, Uskudar, Istanbul 34668, Turkey G. Kayabasoglu Department of Otorhinolaryngology, Sakarya University Training and Research Hospital, Adapazarı, Turkey

This study clearly shows that the dimensional differences in the anatomical clearance between the soft palate and tongue had no effects on retronasal olfaction. Keywords Retronasal olfaction . “Sniffin’ Sticks” . Tongue . Palate . Swallowing

Introduction Research shows that odorants travel to the olfactory receptors by two routes (Fig. 1). Sniffing brings odorants through the nostrils into the nasal cavity (orthonasal olfaction); chewing and swallowing force odorants emitted by foods upward, behind the palate, into the nasal cavity from the rear of the mouth (retronasal olfaction). There are clear differences between orthonasal and retronasal olfaction in neuronal processing and perception so that these two pathways convey two distinct sensory signals (Buettner et al. 2001; Landis et al. 2005; Pfaar et al. 2006; Rombaux et al. 2006 and 2007; Bojanowski and Hummel 2012). Approximately 5 % of the general population is anosmic, but about 15 % have a reduced sense of smell (Murphy et al. 2002; Vennemann et al. 2008; Landis and Hummel 2006). A significant number of patients complain of a reduction in their sense of smell, so it becomes important to reveal the factors that can influence both orthonasal olfaction and retronasal olfaction. Despite this fact, retronasal olfaction so far has received far less attention than its orthonasal counterpart. There are numerous studies about pathologies causing conductive orthonasal olfaction dysfunction (Simopoulos et al. 2012; Becker et al. 2012; Schriever et al. 2013; Nguyen et al. 2012; Garzaro et al. 2012; Haxel et al. 2011). However, there is little data about the factors affecting the retronasal odors from reaching the olfactory mucosa.

Author's personal copy Chem. Percept. (2014) 7:40–45

Fig. 1 The retronasal and orthonasal routes of olfaction

Oral conditions, mouth movements, mastication, and swallowing are known to influence the perception of retronasal stimuli (Heilmann et al. 2002; Welge-Lüssen et al. 2009; Hummel 2008). It is found that adenoid vegetation, narrowing the patency of retropalatal area, has negative effects on retronasal olfaction (Konstantinidis et al. 2005). Likewise, the dimension of the anatomical clearance between the soft palate and tongue might affect the retronasal olfaction because retronasal olfaction is only possible when the soft palatetongue barrier is opened (Buettner et al. 2001 and 2002). Therefore, in this present study, our aim is to evaluate the effect of the anatomical clearance between tongue and soft palate on retronasal olfactory function.

Material and Methods This study was approved by the Clinical Research Ethics Committee of the Istanbul Cerrahpasa Medical Faculty (10.05.13-83045809/11274) and conducted at otorhinolaryngology clinics of the Gulhane Military Medicine Academy Haydarpaşa Training Hospital and Istanbul Surgery Hospital. Informed consent was obtained from all participating subjects. Volunteers with signs of nasal polyposis or rhinosinusitis and with a history of subjective olfactory dysfunction were excluded from the study. Also, volunteers with Grade 2, 3 or 4 tonsil hypertrophy, according to Friedman tonsil grading (Friedman et al. 1999), were excluded from the study. Only volunteers with Grade 1 tonsil size, which implied tonsils hidden within the pillars, were included in the study in order to minimize the tissue effect of the palatine tonsil. For the classification of the clearance between tongue and soft palate, the modified mallampati classification was used.

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The modified mallampati classification was assessed as described (Mallampati et al. 1985; Samsoon and Young 1987) (Fig. 2). The procedure involved asking the patient to comfortably rest in a seated position with the mouth open and the tongue protruding without phonation, providing visualization of the oropharyngeal isthmus. Based on the what was observed, four classifications were assigned: Class 1 allowed the observer to examine the entire uvula and tonsils or pillars; Class 2 allowed observation of the uvula but not the tonsils; Class 3 allowed observation of the soft palate but not the uvula; Class 4 allowed observation of the hard palate only. After rating the Friedman tongue position, the “Sniffin’ Sticks” olfactory test and retronasal olfactory test were conducted with 276 patients. No patient loss occurred during the test processes. Psychophysical testing of orthonasal olfactory function was performed with the validated “Sniffin’ Sticks” test. Odorants were presented in commercially available felt-tip pens (“Sniffin’ Sticks”, Burghart GmbH, Wedel, Germany) (Hummel et al. 1997; Kobal et al. 2000). For odor presentation, the pen’s cap was removed by the experimenter for approximately 3 s, and the tip of the pen was placed approximately 1.0–2.0 cm in front of the nostrils. The test consists of one threshold and two suprathreshold subtests, namely a test for olfactory thresholds of n-butanol, a test for odor discrimination (16 triplets with two different odors), and one for odor identification (16 common odors, presented in a fouralternative, forced-choice procedure). The maximum score of each subtest was 16, resulting in a maximum composite score of 48 (TDI [threshold, discrimination, and identification] score) (Wolfensberger et al. 2000). This score allows a diagnosis of anosmia, hyposmia, or normosmia. In those patients where orthonasal lateralized testing had been performed, results for the best nostril were used for further statistical evaluations (Hummel et al. 2007). None of the subjects was excluded from the study according to the TDI score. For retronasal olfactory testing, a standardized, validated test was used (Heilmann et al. 2002). The test is based on identification of odorized powders or granules presented to the oral cavity (e.g., spices, instant drinks, and instant soups; Table 1). The substances were applied to the midline of the tongue on fenestrated plastic sticks. Subjects were free to sample as much stimulant as needed for identification. This approach also minimized the problem of standardizing the area of stimulation, differences in tongue, or oral cavity size. In a typical trial, the experimenter placed approximately 0.05 g on the middle of the tongue inside the oral cavity. After administration of each powder, participants rinsed their mouths with tap water. The procedure was self-timed. Each substance was identified by means of a closed set with four verbal items using a forced-choice procedure. The test result was a sum score of the correctly identified stimuli.

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Fig. 2 Modified mallampati classification (1–4)

Statistical Analysis

Results

Data analysis was performed by SPSS 21.0 (Statistical Package for Social Sciences, SPSS Inc., Chicago, IL, USA). The normal distribution of considered variables was first evaluated using the Shapiro–Wilk test. Data was shown as mean±standard deviation for continuous variables, and the number of cases was used for categorical variables. Demographic data of the subjects were compared by T or chi-square tests. The T test was used to evaluate the relationship between independent variables and retronasal olfactory testing scores. The effect of gender and palate grading on retronasal olfactory scores was examined with a linear regression model. Correlational analyses were calculated according to Pearson. The level of significance was set at 0.05.

The study was carried out on 276 subjects, and the mean age of the participants was 27±7.7 years ranging from 19 to 53 years. The participants were divided into two groups: Group 1 included participants with mallampati Class 1 and 2 scores; Group 2 included participants with mallampati Class 3 and 4 scores. There were no differences between the groups in terms of age, cigarette smoking, and alcohol consumption. However, there were statistically significant differences in terms of gender between the two groups. Table 2 summarizes the characteristics of each of the variables of interest by groups. Differences in retronasal olfaction scores were not significant between the two groups. The effect of mallampati scoring on retronasal olfactory scores was not found to be significant by linear regression model (p=0.24).

Table 1 Odorized powder or granules used for retronasal olfactory testing

Target item

Distracter items

Brand name (distributor name and city Location)

Ginger Grapefruit Bread Milk Strawberry

Mustard, paprika, curry Lemon, sour cherry, red currant Sauerkraut, pizza, garlic Vanilla, banana, coconut Apple, red currant, tangerine

Zencefil (Doğasal®, Ankara) Grapefruit (Firmenich®, İstanbul) Rusk bread (Etimek®, Bilecik) Süttozu (Pınar®, İstanbul) Çilek (Ori®, İstanbul)

Vanilla Orange Onion Cocoa Celery Mushrooms Paprika Coffee Smoked ham Cloves Garlic Muscat Curry Cinnamon Raspberry

Cherry, banana, honey Raspberry, strawberry, cherry Chives, salami, smoked ham Caramel, muscat, juniper Chives, parsley, carrots Bread, fish, white wine Ginger, curry, mustard Cinnamon, muscat, cocoa Fish, bread, chives Anise, caraway, dill Ham, chives, celery Cinnamon, coffee, cocoa Mustard, cheese, cucumber Honey, caramel, cocoa Peach, pineapple, white grapes

Vanilin (Dr. Oetker®, İzmir) Portakal (Ori®, İstanbul) Soğan (Arifoğlu®, İstanbul) Kakao (Dr. Oetker®, İzmir) Kereviz kök granül (Kurucum®, Isparta) Mushrooms (Firmenich®, İstanbul) Karabiber (Bağdat®, Ankara) Türk Kahvesi (Ülker®, İzmir) Smoked ham (Firmenich®, İstanbul) Karanfil (Arifoğlu®, İstanbul) Sarımsak Granül (Bağdat®, Ankara) Muscat (Firmenich®, İstanbul) Köri (Bağdat®, Ankara) Tarçın (Doğasal®, Ankara) Raspberry (Firmenich®, İstanbul)

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Table 2 Comparison of the two groups (Group 1 included participants with mallampati classes 1 and 2; group 2 included participants with mallampati classes 3 and 4) Characteristics

Group 1

Group 2

p value

Age Male gender/N Smoking (%) Alcohol usage (%) Retronasal olfactory test scores TDI scores

27.5±7.5 145/191 83 (44 %) 37 (19 %) 16 ±2.6 31.2±7.8

26.1±8 78/85 39 (46 %) 13 (15 %) 15.4 ±2.4 29.2±9.9

0.2 0.002 0.7 0.4 0.09 0.1

Also, there was no correlation between gender and retronasal olfactory scores (p=0.57). There was a significant negative correlation between smoking and retronasal olfactory scores (p