Incidence of Olfactory Dysfunction and Associated Factors: A Nationwide Cohort Study From South Korea.

OBJECTIVES: Olfactory dysfunction, a reduced or complete loss of the ability to smell, is gaining attention because of its substantial impact on an individual's quality of life and the possibility that it is an important sign of underlying disease. However, olfactory dysfunction is underdiagnosed in the general population due to diagnostic difficulty and unpredictable prognosis. This study aimed to evaluate the prevalence of clinically diagnosed olfactory dysfunction in South Korea by using well-organized, nationwide, population-based cohort data, and the associations between olfactory dysfunction and risk of neurodegenerative disorders. METHODS: We investigated the Korean National Health Insurance Service-National Sample Cohort for patients diagnosed with olfactory dysfunction according to the International Classification of Diseases. Annual and overall incidence and prevalence of olfactory dysfunction during 2003 to 2013 and patient characteristics were analyzed. Based on those identified patients who were later diagnosed with neurodegenerative disorder, hazard ratios (HRs) of sociodemographic factors and comorbidities associated with neurodegenerative disorder were evaluated using a Cox proportional hazard regression model. RESULTS: In total, 6296 patients were clinically diagnosed with olfactory dysfunction during the study period (524.67 patients/year). The prevalence increased annually and was higher in female patients. The incidence of neurodegenerative disorders among patients with olfactory dysfunction was 4.2% within the study period. Multivariate cox regression analysis of the patients (n = 249) revealed that diabetes mellitus (HR = 1.976) and depression (HR = 2.758) were significant risk factors. CONCLUSIONS: Olfactory dysfunction is underdiagnosed in South Korea, but it is clinically important considering the possibility of presymptom of neurodegenerative disorders. In clinical practice, we should consider its association with neurodegenerative disorders and possibly other systemic conditions.

The Associations of Tonsillectomy with Adenoidectomy with Pneumonia and Appendicitis Based on National Sample Cohort Data from the Korean National Health Insurance Service.

Introduction The association between tonsillectomy with adenoidectomy (T&A) with appendicitis is controversial, and the association of T&A with pneumonia has not been investigated. Objective To investigate the associations of T&A with pneumonia and appendicitis using data from the Korean National Health Insurance Service National Sample Cohort. Methods We selected patients between the ages of 3 and 10 years who had undergone T&A in 2005 and were monitored since the performance of the T&A until 2013. The control group was established to have similar propensities for demographic characteristics compared to the T&A group. For eight years after the T&A, the number of patients with a diagnosis of pneumonia, patients who were admitted due to pneumonia, and those who underwent appendectomy were analyzed. The risk factors for pneumonia and appendectomy were analyzed. Results The number of pneumonia diagnoses was significantly higher in the T&A group than in the control group ( p = 0.023), but there were no significant differences in the number of admissions due to pneumonia between the 2 groups ( p = 0.155). Younger age and T&A were significant risk factors for the development of pneumonia. There were no significant differences in the number of appendectomies between the T&A and the control groups ( p = 0.425), neither were there significant risk factors for appendectomy. Conclusion Tonsillectomy with adenoidectomy was associated with an increase in pneumonia diagnoses, but it was not associated with the number of appendectomies. The associations of T&A with pneumonia and appendicitis were analyzed in this population-based study.

Monthly and seasonal variations in benign paroxysmal positional vertigo.

BACKGROUND: Several studies on seasonal variation in benign paroxysmal positional vertigo (BPPV) have been reported. However, the association between season and BPPV remains controversial; thus, further study is required. OBJECTIVE: We analyzed patients with BPPV to evaluate monthly and seasonal variations. METHODS: Patients with BPPV seen between 2013 and 2017 were retrospectively enrolled in this study. Differences among the months and seasons of BPPV visits were analyzed. Patients were divided into two groups according to age (65 years or older and younger than 65 years) and sex, respectively, and the differences were analyzed in each group. RESULTS: There was no significant difference in the monthly or seasonal distribution of BPPV in the 1,216 patients. There was also no significant difference in the monthly or seasonal distribution in the older and younger groups or in male and female patients. CONCLUSIONS: There was no significant difference in the monthly or seasonal distribution of patients with BPPV. Additional studies on seasonal variation in BPPV are required in terms of not only vitamin D levels but also other associated factors.

The effect of tonsillectomy with adenoidectomy on medical services used in association with otitis media based on Korean national sample cohort data.

BACKGROUND: The effect of tonsillectomy with adenoidectomy (T&A) on otitis media has been investigated, but there have been no reports of the relationship between T&A and medical services used in association with otitis media. We investigated the effect of T&A on otitis media with regard to the number and cost of medical services used. METHODS: From the National Health Insurance Service National Sample Cohort data in Korea, we selected patients 7 years old or younger in 2002 who had T&A in 2005 while between the ages of three and ten. A control group was established matching the patient group with similar propensities of demographic characteristics. The number and cost of medical services used in association with otitis media were analyzed for 3 years before T&A through 8 years after T&A. RESULTS: The total number of patients was 1,338, with 227 in the T&A group and 1,111 in the non-T&A group. The number of medical services used was not significantly different between the T&A and non-T&A groups before and after surgery. The cost of medical services used was significantly higher in the T&A group than in the non-T&A group one year before surgery. The cost of medical services used was not significantly different between the two groups after surgery. CONCLUSIONS: There were no significant differences between the T&A and non-T&A groups in the number and cost of medical services used in association with otitis media after surgery.

Slug is a novel molecular target for head and neck squamous cell carcinoma stem-like cells.

BACKGROUND: The acquisition of stem-like phenotype is partly attributed to the induction of epithelial-mesenchymal transition (EMT). Thus, the activation of factors involved in EMT can be linked to cancer stem cell genesis. However, the underlying mechanisms in head and neck squamous cell carcinoma (HNSCC) remain largely unknown. Herein, we investigate whether slug, one of the major effectors of EMT, affects the stemness of HNSCC cells. METHODS: We performed in vitro experiments to determine whether slug gene manipulation can influence the stemness phenotypes, including the capacity for self-renewal, expression of putative stemness markers, chemoresistance, and invasion in HNSCC cells. Further, we identified whether Slug knockout attenuates tumorigenicity of HNSCC cells in vivo. Finally, we examined whether prognosis of HNSCC patients after curative treatment may be affected by the level of slug expression. RESULTS: Overexpression of slug promoted self-renewal of HNSCC cells via activation of sphere formation, the expression of stem cell markers, and induction of chemoresistance to cisplatin. Also, slug overexpression increased the migration and invasion of HNSCC cells in vitro and was mainly observed during the invasion in HNSCC xenograft mouse model. By contrast, slug expression knockdown abrogated their self-renewal capacity, stemness-associated gene expression, and cisplatin chemoresistance. Furthermore, high levels of slug expression correlated with poor prognosis of patients with HNSCC. CONCLUSION: Inhibition of slug expression may represent a novel therapeutic strategy targeting HNSCC stem-like cells.

Prognostic implications of Fibroblast growth factor receptor 1 (FGFR1) gene amplification and protein overexpression in hypopharyngeal and laryngeal squamous cell carcinoma.

BACKGROUND: The gene encoding fibroblast growth factor receptor 1 (FGFR1) is emerging as a therapeutic and prognostic biomarker in various cancer types, including head and neck squamous cell carcinoma (SCC). Here, we investigated the clinicopathologic implication of FGFR1 gene amplification and protein overexpression in hypopharyngeal and laryngeal SCC. METHODS: Fluorescence in situ hybridization and immunohistochemistry were performed to determine FGFR1 gene amplification and protein overexpression in 209 surgically resected cases. RESULTS: FGFR1 amplification observed in 8 (8/66, 12.1%; 6 hypopharynx and 2 larynx) patients and high FGFR1 expression in 21 (21/199, 10.6%) patients significantly correlated with lymph node metastasis and advanced pathological stages. FGFR1 amplification was also associated with worse disease-free survival in multivariate analysis (hazard ratio = 4.527, P = 0.032). High FGFR1 expression was more frequently observed, consistent with the worsening of the degree of histologic differentiation. CONCLUSIONS: FGFR1 amplification may serve as an independent prognostic factor for disease-free survival in hypopharyngeal and laryngeal SCC. Aberrant FGFR signaling caused by FGFR1 gene amplification or protein overexpression may play a crucial role in the malignant evolution and progression of hypopharyngeal and laryngeal SCC, and offer novel therapeutic opportunities in patients with hypopharyngeal and laryngeal SCC that usually lack specific therapeutic targets.

Role of integrin ß1 as a biomarker of stemness in head and neck squamous cell carcinoma.

OBJECTIVES: Signaling between cancer stem cells (CSC) and their extracellular matrix has a crucial role in CSC progression and maintenance. However, mediators of this signaling pathway in head and neck squamous cell carcinoma (HNSCC) are largely unknown. Here, we explored whether integrin ß1, which is one of the key regulators of the communication between cells and their microenvironment, affected the stemness of HNSCC cells. MATERIALS AND METHODS: We examined self-renewal capacity, chemoresistance, and xenograft tumorigenicity after knockdown of integrin ß1 in primary HNSCC cells. In addition, we studied the role of focal adhesion kinase (FAK), an intracellular downstream molecule of integrin signaling, in influencing stemness of HNSCC. The relevance of Notch1 and integrin ß1 interactions in HNSCC cells was also examined. Finally, immunohistochemical analysis was carried out to test whether the coexpression of integrin ß1 and Notch1 in the samples from HNSCC patients correlated with their survival. RESULTS: Targeting integrin ß1 in HNSCC cells inhibited self-renewal, chemoresistance, and in vivo tumor-forming capacity. Treatment with an inhibitor of FAK decreased self-renewal capacities and expression of various putative stem cell markers (Oct4, Sox2, and Nanog) in a dose-dependent manner. Moreover, knockdown of integrin ß1 decreased the expression of Notch1 and its target genes (Hey1 and Hes1). Notably, HNSCC patients demonstrating simultaneous expression of integrin ß1 and Notch1 in their tissue samples had significantly worse survival rate. CONCLUSION: Integrin ß1/Notch1 axis has a significant role in the regulation of stemness in HNSCC.

Radioprotective effect of epicatechin in cultured human fibroblasts and zebrafish.

Radiation-induced normal cell damage limits the delivery of high-dose radiation to targeted cancer. This study investigated the effect of epicatechin (EC), a minor component of green tea extracts, on radiation-induced cellular damage in vitro in primary cultured human fibroblasts and in vivo in a zebrafish model. Cell viability, proliferation and wound-healing efficacy, mitochondrial membrane potential, and reactive oxygen species (ROS) generation as well as changes in the signaling pathway related to apoptosis were investigated in fibroblasts. The therapeutic effects of EC were explored in a zebrafish model. EC increased clonogenic survival and restored the migration ability of the fibroblasts after irradiation. EC inhibited radiation-induced ROS generation, mitochondrial dysfunction and cell death. EC significantly reduced the expression of p-JNK, p-38, and cleaved caspase-3 compared with their significant increase after radiation treatment. EC attenuated the radiation-induced embryotoxicity in a zebrafish model. These results suggest that EC represents an effective means of reducing cellular damage and facilitating wound healing after radiation exposure.

Effect of epicatechin against radiation-induced oral mucositis: in vitro and in vivo study.

PURPOSE: Radiation-induced oral mucositis limits the delivery of high-dose radiation to head and neck cancer. This study investigated the effectiveness of epicatechin (EC), a component of green tea extracts, on radiation-induced oral mucositis in vitro and in vivo. EXPERIMENTAL DESIGN: The effect of EC on radiation-induced cytotoxicity was analyzed in the human keratinocyte line HaCaT. Radiation-induced apoptosis, change in mitochondrial membrane potential (MMP), reactive oxygen species (ROS) generation and changes in the signaling pathway were investigated. In vivo therapeutic effects of EC for oral mucositis were explored in a rat model. Rats were monitored by daily inspections of the oral cavity, amount of oral intake, weight change and survival rate. For histopathologic evaluation, hematoxylin-eosin staining and TUNEL staining were performed. RESULTS: EC significantly inhibited radiation-induced apoptosis, change of MMP, and intracellular ROS generation in HaCaT cells. EC treatment markedly attenuated the expression of p-JNK, p-38, and cleaved caspase-3 after irradiation in the HaCaT cells. Rats with radiation-induced oral mucositis showed decreased oral intake, weight and survival rate, but oral administration of EC significantly restored all three parameters. Histopathologic changes were significantly decreased in the EC-treated irradiated rats. TUNEL staining of rat oral mucosa revealed that EC treatment significantly decreased radiation-induced apoptotic cells. CONCLUSIONS: This study suggests that EC significantly inhibited radiation-induced apoptosis in keratinocytes and rat oral mucosa and may be a safe and effective candidate treatment for the prevention of radiation-induced mucositis.

Characteristics, management of the neck, and oncological outcomes of malignant minor salivary gland tumours in the oral and sinonasal regions.

The aim of this study was to evaluate the characteristics of malignant tumours of the minor salivary glands in the oral and sinonasal regions, to make sure that the neck was managed correctly, and to identify oncological outcomes, retrospectively, at a single hospital. A total of 60 patients were reviewed. Forty-nine patients had intraoral lesions and 11 had sinonasal lesions. Of the 60 patients, 28 had stage I to II malignant tumours, and 32 had stage III to IV tumours. Treatment was almost exclusively surgical. One of the 16 patients whose nodes were clinically clear had an elective neck dissection. Adjuvant radiotherapy was given if indicated. The mean follow-up period was 52 months (range 13-190). Sinonasal lesions were all advanced T-stage at diagnosis, had more invaded resection margins, and a higher local recurrence rate than intraoral lesions. There was no regional recurrence in those patients whose nodes were clinically invaded and who had therapeutic neck dissection, or in the patient whose nodes were clinically clear and who had an elective neck dissection. Occult metastases developed exclusively in adenoid cystic carcinomas (ACC), the rate of which was 4/16. Regional recurrence developed in 4 patients who had never had elective treatment to the neck 2 of whom mixed pattern ACC and 2 who had low grade mucoepidermoid carcinomas (MEC). The overall survival was 90% at 2 years, 77% at 5 years, and 74% at 10 years. Sinonasal minor salivary gland tumours require careful follow-up because resection margins are more likely to be invaded by tumour, and they have a higher local recurrence rate than intraoral lesions. Elective neck dissection is needed, particularly for MEC and also to prevent regional recurrence in ACC.

Endoscopic resection of upper neck masses via retroauricular approach is feasible with excellent cosmetic outcomes.

PURPOSE: In this study, the authors introduce and evaluate the feasibility of endoscopic resection using the retroauricular approach for various benign lesions of the upper neck. PATIENTS AND METHODS: A retrospective comparative analysis was performed on the clinical outcomes of patients who underwent surgery for upper neck masses as endoscopic resection using the retroauricular approach or conventional transcervical resection at the authors' center from January 2010 through August 2011. The primary outcome was the cosmetic satisfaction of the patients in each group. In addition, the feasibility of the procedure was evaluated by comparing the operation time; hospital stay; amount and duration of drainage; complications such as marginal mandibular nerve, lingual, or hypoglossal nerve palsy; paresthesia of the ear lobe; and wound problems such as hematoma and skin necrosis. Statistical analysis was performed by independent-samples t test and the Fisher exact test, and a P value less than .05 was considered statistically significant. RESULTS: Thirty-six patients underwent endoscopic resection (endo group; 15 men, 21 women; mean age, 38.8 ± 15.0 years) and 40 patients underwent conventional transcervical resection (conventional group; 18 men, 22 women; mean age, 45.1 ± 14.1 years). The operating time in the endo group was longer than in the conventional group (P = .003). No significant difference was observed in the overall perioperative complications between the 2 groups. Cosmetic satisfaction evaluated with a graded scale showed much better results in the endo group (P < .001). CONCLUSIONS: Endoscopic resection using the retroauricular approach is feasible for various benign upper neck masses when conducted by an experienced endoscopic surgeon, with excellent cosmetic results.

Endoscopic axillo-breast approach for benign neck mass excision.

OBJECTIVES/HYPOTHESIS: Benign neck masses are usually found in younger patients, who are more likely to be concerned about postoperative scars. Until recently, a direct approach through a transcervical incision along the mass has been accepted as a standard surgical procedure for the benign neck mass. However, this conventional transcervical approach leaves a visible scar on the neck, regardless of the size of the incision. We assumed that an endoscopic gasless axillo-breast (A-B) approach might be a good alternative method for excision of benign neck masses. The aim of this study was to determine the safety and feasibility of a gasless A-B approach for the excision of benign neck masses by comparing it to the conventional open approach. STUDY DESIGN: Case series. METHODS: We prospectively compared the outcomes of endoscopic removal of benign neck lesions with the outcomes of conventional open surgery. RESULTS: Most patients in the endoscopy group were women, and the mean age was younger than in the open group. Although operative time was longer and amount of drainage was larger in the endoscopy group, there was no statistically significant difference in duration of drainage, hospitalization period, complication rate, and pain score. Endoscopically treated patients were more satisfied with the cosmetic outcome of the surgery than patients in the conventional open group. CONCLUSIONS: Endoscopic excision via an A-B approach without gas insufflation could be a good substitute for conventional transcervical excision in selected cases of benign neck lesion.

Larynx-Preserving Partial Pharyngectomy via Lateral Pharyngotomy for the Treatment of Small (T(1~2)) Hypopharyngeal Squamous Cell Carcinoma.

OBJECTIVES: To evaluate the oncologic and functional results of larynx-preserving partial pharyngectomy (LPP) via lateral pharyngotomy approach as a primary treatment for small (T1 or T2) hypopharyngeal squamous cell carcinoma (HPSCC). METHODS: We performed a retrospective review of 23 patients who underwent LPP through lateral pharyngotomy approach for small HPSCC at the our department between January 1991 and June 2007. Fourteen (61%) patients had adjuvant postoperative radiotherapy. RESULTS: The 2-years and 5-years disease specific survival rate was 77% and 61%, respectively. Nine patients (39%) had tumor recurrence. The most common pattern of recurrence was isolated distant failure (n=4, 44%) followed by local (n=2, 22%) and loco-regional (n=3, 34%) recurrence. The ultimate cure rate of the primary tumor was 87% (20 of 23). Twenty-two of the 23 patients (95%) could be decannulated, tolerate an oral diet, and had acceptable postoperative phonatory function. CONCLUSION: LPP via lateral pharyngotomy approach appears to be a feasible procedure for selected small HPSCC patients in terms of both oncologic and functional outcomes.

Diallyl sulfide induces growth inhibition and apoptosis of anaplastic thyroid cancer cells by mitochondrial signaling pathway.

Anaplastic thyroid carcinoma (ATC) is one of the most lethal solid tumors arising thyroid gland with dismal prognosis. One of the constituents of garlic, diallyl sulfide (DAS) was shown to inhibit chemically induced carcinogenesis in many animal models. This study examined whether DAS could induce growth inhibition and apoptosis in ATC cells. In MTT assay, DAS treatment inhibited the proliferation of ARO cells in a dose-dependent manner. Flow cytometric analysis showed that DAS treatment increased the accumulation of sub-G1 DNA and concomitant accumulation of cells in the G2/M phase in a dose-dependent manner. In addition, DAS-induced apoptosis was associated with a decrease in the level of Bcl-2 expression and an increase in the level of Bax expression, and cytochrome c was remarkably released from mitochondrial into the cytosol by DAS. Furthermore, caspase-9 and caspase-3 were activated by DAS, and DAS cleaved PARP. Taken together, DAS decreased cell proliferation and induced apoptosis via mitochondrial signaling pathway in ATC cells.

Tissue-engineered allograft tracheal cartilage using fibrin/hyaluronan composite gel and its in vivo implantation.

OBJECTIVES/HYPOTHESIS: Treatment and management of tracheal defects remain challenging in head and neck surgery. Various reconstruction techniques have been used, with no consensus on the best approach. The purpose of this study was to explore a novel strategy to fabricate tissue-engineered trachea by using fibrin/hyaluronic acid (HA) composite gel and evaluate the feasibility of creating tracheal cartilage. STUDY DESIGN: A preliminary animal experiment. METHODS: Chondrocytes from rabbit cartilage were expanded and seeded into a culture dish at high density to form mechanically stable allograft tracheal cartilage using fibrin/HA composite gel. After a longitudinal cervical skin incision, the trachea was exposed and a rectangular defect (1 x 0.5 cm) was created on the cervical trachea by scalpel on six rabbits. Tissue-engineered cartilage using fibrin/HA composite was trimmed and fixed to defect boundaries with Tissucol (Baxter International, Deerfield, IL). Postoperatively, the site was evaluated endoscopically, histologically, radiologically, and functionally. RESULTS: Postoperatively, rigid telescopic examination showed that the implanted scaffolds in all cases were completely covered with regenerated mucosa without granulation or stenosis. Histologic data showed ciliated epithelium regenerated at the operated site from 2 months postoperatively. Ciliary beat frequency of ciliated epithelium on implants was very similar to normal respiratory mucosa. Computed tomography images revealed fine luminal contour of the regenerated site. However, allograft cartilage implanted was found to be partially preserved on the postoperative specimen. CONCLUSIONS: The tracheal luminal contour and functional epithelial regeneration without graft rejection and inflammation were observed after repair of a tracheal resection using allogeneic implants with chondrocytes cultured with fibrin/HA.

Role of primary surgery for early-stage (T1-2N0) squamous cell carcinoma of the oropharynx.

To evaluate treatment outcomes and the role of primary definitive surgery for T(1-2), clinically N(0) oropharyngeal squamous cell carcinoma (OPSCC) patients, we performed a retrospective analysis of 46 consecutive cases treated primarily by surgery and/or postoperative radiotherapy at Yonsei University between May 1992 and December 2006. Twelve patients were T(1) and 34 were T(2). The most common location was the tonsil (54%), followed by the soft palate (19%), the base of the tongue (BOT) (15%) and the posterior wall (12%). Occult lymph node metastasis was noted in 12 cases (26%). Seventeen patients (37%) received adjuvant radiotherapy. The 5-year disease-specific survival rate (DSSR) was 83%: 100% for clinical stage I (T(1)N(0)) and 74% for clinical stage II (T(2)N(0)). The 5-year DSSR of patients with surgery alone was 86%. Thirteen of 14 patients (93%) treated with conservative surgery alone without mandible-splitting or adjuvant radiotherapy attained disease-free status. In addition, 25 of 40 patients (63%) with disease-free status were treated with surgery alone. Almost 30% of all patients may be candidates for adjuvant chemotherapy through histopathologic analysis according to the National Comprehensive Cancer Network (2007) guidelines. The results of the present study demonstrate excellent oncologic outcomes with primary surgery for the treatment of early-stage OPSCC and suggest that surgery offers the best opportunity to identify patients in whom adjuvant radio- or chemotherapy may be most appropriately applied.

The effect of allergen provocation on the nasal cycle estimated by acoustic rhinometry.

CONCLUSION: The overall duration and reciprocity of the nasal cycle were not changed after allergen provocation. The duration of immediate response was 38 min, but the amplitude of the nasal cycle was increased significantly after allergen provocation. OBJECTIVE: Nasal airflow is asymmetrical and subjected to spontaneous reciprocal changes which are referred to as the nasal cycle. Limited information is available on how this is affected by allergens. The purpose of this study was to evaluate the effects of allergen provocation on the nasal cycle. MATERIALS AND METHODS: This study was performed on 25 patients with allergic rhinitis and 25 subjects in a control group with no symptoms of allergic rhinitis. Acoustic rhinometry was used to test patients before and after allergen provocation. The patients underwent acoustic rhinometry at 15-min intervals for evaluation of nasal cycle and 3-min intervals for immediate response. RESULTS: With the allergic patients, 21 of the 25 patients (84.0%) showed a nasal cycle and they still had a nasal cycle after the allergen provocation. In the study on the changes in the immediate responses, the average recovery time was 38 min and the reduction rate of the non-patent side was higher than that of the patent side. Also, the average period of the nasal cycle was 153 min before the allergen provocation and 140 min on average after the allergen provocation; there were no statistical differences. The amplitude of each nasal cycle increased after allergen provocation and the difference had statistical meaning.

Particle image velocimetry measurements for the study of nasal airflow.

CONCLUSIONS: Particle image velocimetry (PIV) permits investigation of the distribution and velocity of the airflow in the nasal cavity. During breathing, the main laminar flow stream passes through the middle meatus and turbulent flow can be detected under physiologic conditions. OBJECTIVES: Physical models or casts of the nasal cavity have been utilized in several studies in an effort to understand its aerodynamics. PIV is a new technique for measuring the aerodynamic properties of tubular structures. In this article we evaluate nasal airflow characteristics during physiologic breathing under normal conditions and the usefulness of PIV. MATERIAL AND METHODS: A nasal model cast obtained by a combination of rapid prototyping and solidification of clear silicone was connected to a pump which simulated the physiological pressure in the upper airway system. A glycerol-water mixture was used as the flow material. The airstream was marked with spherical polyvinyl particles, observed through solidified clear silicone and analyzed using PIV. RESULTS: The main flow within the cavity, which was mostly laminar, passed through the middle meatus. Turbulence was clearly visible in the anteroinferior part of the middle turbinate. The flow rate was highest at the middle meatus during inspiration and expiration.