The Olfactory System: Basic Anatomy and Physiology for General Otorhinolaryngologists

Olfaction is one of the five basic human senses, and it is known to be one of the most primitive senses. The sense of olfaction may have been critical for human survival in prehistoric society, and although many believe its importance has diminished over time, it continues to have an impact on human interaction, bonding, and propagation of the species. Even if we are unaware of it, the sense of smell greatly affects our lives and is closely related to overall quality of life and health. Nonetheless, olfaction has been neglected from a scientific perspective compared to other senses. However, olfaction has recently received substantial attention since the loss of smell and taste has been noted as a key symptom of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Studies investigating olfaction loss in association with coronavirus disease 2019 (COVID-19) have revealed that olfactory dysfunction can be both conductive and sensorineural, possibly causing structural changes in the brain. Olfactory training is an effective treatment for olfactory dysfunction, suggesting the reorganization of neural associations. A reduced ability to smell may also alert suspicion for neurodegenerative or psychiatric disorders. Here, we summarize the basic knowledge that we, as otorhinolaryngologists, should have about the sense of smell and the peripheral and central olfactory pathways for managing and helping patients with olfactory dysfunction.

The Usefulness of Medial Sural Artery Perforator Free Flap for Head and Neck Reconstruction / 대한이비인후과학회지

Background and Objectives@# The ideal flap for head and neck reconstruction should be pliable, have sufficiently long pedicle and minimize donor defects. Anterolateral thigh free flap (ALTFF) and radial forearm free flap (RFFF) have been the workhorse flaps for head and neck reconstruction. However, ALTFF is too bulky and RFFF leaves a conspicuous scar on the donner site. Medial sural artery perforator free flap (MSAPFF) is a possible alternative, which has the benefit of thin RFFF and low donor site morbidity of ALTFF. Here, we evaluated for the first time the usefulness of MSAPF for head and neck reconstruction in Korean patients. Subjects and Method We carried out a retrospective study of patients who underwent MSAPFF for head and neck reconstruction from October 2018 to July 2019 by retrieving their data from electronic medical records. Patient characteristics, flap characteristics, surgical outcomes, and complications of donor sites were analyzed. @*Results@# Eight patients underwent MSAPFF reconstruction after head and neck surgery. The recipient sites were the following: the floor of the mouth, palate, tongue, the base of the tongue and nasolabial fold. The average median flap size was 34.1 cm2 (range 17.5-50 cm2), length 7.1 cm (5.0-10.0 cm), width 4.7 cm (range 3.5-5.0 cm), and pedicle length 9.2 cm (range 8-10 cm). There was one flap failure because of pedicle arterial insufficiency. All donor sites were closed primarily without any complication. @*Conclusion@# Based on the findings of this study, MSAPFF may be a new workhorse flap because it has thin, pliable tissue with low donor-site morbidity for head and neck reconstruction.

Comparison Between Signature Cytokines of Nasal Tissues in Subtypes of Chronic Rhinosinusitis

PURPOSE: Endotype in chronic rhinosinusitis (CRS) has been established in the last decade. However, the exact immunologic profile of CRS still has controversy because it has a considerable immunologic heterogeneity. Therefore, we investigated various inflammatory mediators according to different nasal tissues in chronic rhinosinusitis and compared them within the same subject. METHODS: We collected uncinate process mucosa (UP) and nasal polyp (NP) tissues from controls, CRS without NP (CRSsNP) and CRS with NP (CRSwNP). Expression levels of 28 inflammatory mediators including T helper (Th) 1, Th2, Th17, proinflammatory cytokines and remodeling markers were determined by multiplex immunoassay and were analyzed using paired tests as well as principal component analysis (PCA) to investigate endotype in each subtype of CRS. RESULTS: Signature inflammatory mediators are interleukin (IL)-5, C-C motif chemokine ligand (CCL)-24, monocyte chemoattractant protein (MCP)-4, and vascular cell adhesion molecule (VCAM)-1 in eosinophilic NP, whereas IL-17A, IL-1β, and matrix metallopeptidase (MMP)-9 were detected as signature inflammatory markers in non-eosinophilic NP. Despite differences in inflammatory cytokine profile between eosinophilic and non-eosinophilic NP, the common upregulation of IL-5, CCL-11, IL-23, IL-2Rα, VCAM-1, MMP-3 and MMP-9 were shown in NP compared to UP within the same subject. In the PCA, we observed that Th2 immune response was helpful in discriminating between nasal tissues in subtypes of CRS and that there was a partial overlap between non-eosinophilic NP and eosinophilic NP in terms of Th2 mediators. CONCLUSIONS: Commonly upregulated mediators in NP were Th2-associated, compared with UP regardless of CRS subtypes, whereas signature markers were distinct in each NP subtype. These findings imply that Th2 inflammatory responses may play a role in the development of NP regardless of CRSwNP subtypes.

Effects of Residual Hearing on the Auditory Steady State Response for Cochlear Implantation in Children

BACKGROUND AND OBJECTIVES: We aim to explore the effects of residual auditory steady state response (ASSR) on cochlear implantation (CI) outcomes in children lacking auditory brainstem responses (ABRs). SUBJECTS AND METHODS: We retrospectively reviewed the data of child CI recipients lacking ABRs. All ears were divided into two groups: with residual ASSR and without ASSR. For each frequency, the T- and C-levels and the electrical dynamic ranges of postoperative 3-month and 1-year mappings were compared between the groups. To evaluate speech perception, patients who received simultaneous bilateral CIs were divided into two groups: group 1 exhibited responses at all frequencies in both ears; in group 2, at least one ear evidenced no response. The Categories of Auditory Perception (CAP) and Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) scores were compared between the groups. RESULTS: We enrolled 16 patients. At 2 kHz, the postoperative 3-month and 1-year T-levels of patients with residual hearing were lower than those of hearing loss group (p=0.001, p=0.035). In residual hearing group, the ASSR threshold correlated positively with the postoperative 1-year T-level (p=0.012, R² =0.276) and C-level (p=0.002, R² =0.374). Of 10 simultaneous bilateral CI recipients, 5 exhibited ASSRs at all frequencies and the other 5 showed no response at ≥1 frequency. The latter had higher CAP scores at the postoperative 1-year (p=0.018). CONCLUSIONS: In children exhibiting hearing loss in ABR testing, residual hearing at 2 kHz ASSR correlated positively with the post-CI T-level. Those with ASSRs at all frequencies had significantly lower CAP scores at the postoperative 1year. CI should not be delayed when marginal residual hearing is evident in ASSR.

Analysis of Sleep Questionnaires of Commercial Vehicle Operators in Korea / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Obstructive sleep apnea (OSA) is highly prevalent in commercial vehicle operators (CMVOs). This study aimed to evaluate the poor sleep quality, daytime sleepiness, and the prevalence of self-reported OSA in CMVOs. SUBJECTS AND METHOD: We performed a retrospective review of the medical records of patients who visited a single institution with sleep problems from 2011 January to 2016 December. Among the patients, a total of 38 CMVOs was analyzed. Clinical information, questionnaires about sleep quality (Pittsburg sleep questionnaire, PSQI), excessive daytime sleepiness (Epworth sleepiness scale, ESS) and risk factors for OSA (STOP-Bang) were analyzed. The frequency of motor vehicle accidents and near accidents was assessed, and polysomnography (PSG) was used for OSA diagnosis purposes. RESULTS: The mean age of the study population was 45.3±11.8 years. The average score of PSQI, ESS, and STOP-Bang were 6.75±4.22, 10.79±7.12, and 4.62±3.34, respectively. A significant association between near accidents and high-risk group of OSA was observed [odds ratio (OR)=2.73, 95% confidence interval (CI)=1.08–4.48]. Subjects with poor sleep quality showed significantly increased risk of near accidents (OR=2.34, 95% CI=1.01–3.56). Receiver operating characteristic curves of STOP-Bang questionnaire using apnea-hypopnea index (cut-off value=5) indicates that suspected OSA group predicted by STOP-Bang score was significantly correlated with OSA severity (area under curve=0.72, sensitivity 77.1%, specificity 59.4%). CONCLUSION: Administration of STOP-Bang questionnaire before a PSG can identify high-risk subjects, supporting its further use in OSA screening of CMVOs.

Analysis of Sleep Questionnaires of Commercial Vehicle Operators in Korea / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES@#Obstructive sleep apnea (OSA) is highly prevalent in commercial vehicle operators (CMVOs). This study aimed to evaluate the poor sleep quality, daytime sleepiness, and the prevalence of self-reported OSA in CMVOs.SUBJECTS AND METHOD: We performed a retrospective review of the medical records of patients who visited a single institution with sleep problems from 2011 January to 2016 December. Among the patients, a total of 38 CMVOs was analyzed. Clinical information, questionnaires about sleep quality (Pittsburg sleep questionnaire, PSQI), excessive daytime sleepiness (Epworth sleepiness scale, ESS) and risk factors for OSA (STOP-Bang) were analyzed. The frequency of motor vehicle accidents and near accidents was assessed, and polysomnography (PSG) was used for OSA diagnosis purposes.@*RESULTS@#The mean age of the study population was 45.3±11.8 years. The average score of PSQI, ESS, and STOP-Bang were 6.75±4.22, 10.79±7.12, and 4.62±3.34, respectively. A significant association between near accidents and high-risk group of OSA was observed [odds ratio (OR)=2.73, 95% confidence interval (CI)=1.08–4.48]. Subjects with poor sleep quality showed significantly increased risk of near accidents (OR=2.34, 95% CI=1.01–3.56). Receiver operating characteristic curves of STOP-Bang questionnaire using apnea-hypopnea index (cut-off value=5) indicates that suspected OSA group predicted by STOP-Bang score was significantly correlated with OSA severity (area under curve=0.72, sensitivity 77.1%, specificity 59.4%).@*CONCLUSION@#Administration of STOP-Bang questionnaire before a PSG can identify high-risk subjects, supporting its further use in OSA screening of CMVOs.