Impact of Middle versus Inferior Total Turbinectomy on Nasal Aerodynamics

Numerical and experimental analysis of pollen inhalation exposure in nasal airways following various middle turbinectomy

BACKGROUND

Middle turbinectomy (MT) has always been controversial. MT significantly alters the anatomy and redistributes the inhaled air. The current study is designed to quantify the effect of MT with varying resection volumes on airflow and associated pollen inhalation exposure characteristics in the nasal airways.

METHODS

Six realistic models following bilateral comprehensive Functional Endoscopic Sinus Surgery (FESS) deriving from CT images were constructed and their corresponding post-MT models with four types of MT procedures were virtually conducted. Inhalation exposure to pollen particles was simulated by the Computational Fluid-Particle Dynamics (CFPD) approach and validated through in vitro experiments.

RESULTS

Following the excision of the middle turbinate, a significant escalation in airflow was observed within the upper-middle region of the nasal cavities. Pollen deposition was observed to be more prominent in the nasal septum, laryngopharynx, and maxillary sinus, varying with the types of MT procedures. Notably, particles with diameters smaller than 50 μm exhibited two distinct "high peaks" and three "small peaks" within the nasal airways.

CONCLUSION

MT resulted in increased airflow volume within the upper-middle region of the nasal cavities. Following MT, notable shifts in pollen particle deposition hot spots were observed, transitioning from the nasal vestibule, nasal septum, and middle meatus to the nasal septum and laryngopharynx. These findings are anticipated to contribute valuable perspectives on pollen inhalation exposure risk assessments following diverse MT surgical interventions.

In-silico decongested trial effects on the impaired breathing function of a bulldog suffering from severe brachycephalic obstructive airway syndrome

BACKGROUND AND OBJECTIVE

Brachycephalic obstructive airway syndrome (BOAS) susceptible dogs (e.g., French bulldog), suffer health complications related to deficient breathing primarily due to anatomical airway geometry. Surgical interventions are known to provide acceptable functional and cosmetic results; however, the long-term post-surgery outcome is not well known. In silico analysis provides an objective measure to quantify the respiratory function in postoperative dogs which is critical for successful long-term outcomes. A virtual surgery to open the airway can explore the ability for improved breathing in an obstructed airway of a patient dog, thus supporting surgeons in pre-surgery planning using computational fluid dynamics.

METHODS

In this study five surgical interventions were generated with a gradual increment of decongested levels in a bulldog based on computed tomography images. The effects of the decongested airways on the breathing function of a patient bulldog, i.e., airflow characteristics, pressure drop, wall shear stress, and air-conditioning capacity, were quantified by benchmarking against a clinically healthy bulldog using computational fluid dynamics (CFD) method.

RESULTS

Our findings demonstrated a promising decrease in excessive airstream velocity, pressure drop, and wall shear stress in virtual surgical scenarios, while constantly preserving adequate air-conditioning efficiency. A linear fit curve was proposed to correlate the reduction in the pressure drop and decongested level.

CONCLUSIONS

The in silico analysis is a viable tool providing visual and quantitative insight into new unexplored surgical techniques.

Swing Door Compressive Fracture Technique for Turbinoplasty: Retrospective Study Based on Computed Tomography and NOSE Scale

BACKGROUND

Treatment of inferior turbinate hypertrophy is performed using different techniques in rhinoplasty. However, the reported results are not consistent. In this study, we aimed to evaluate the outcomes of Swing door compressive fracture (SDCF) technique for turbinoplasty using computed tomography (CT) and Nasal Obstruction Symptom Evaluation (NOSE) scale.

METHODS

This study involved retrospective analysis of 24 patients who underwent inferior turbinoplasty using Swing door compressive fracture (SDCF) technique with or without septoplasty. The angle between the inferior turbinate and lateral nasal wall, total area, inferior turbinate area and the area medial to inferior turbinate were measured preoperatively and postoperatively using coronal section CT images for objective evaluation. Moreover, the NOSE scale was used for subjective evaluation.

RESULTS

The angle between inferior turbinate and lateral nasal wall was decreased by 25.3% after the treatment (p <0.0001). Inevitably, postoperative total nasal airway area (area 1) did not face a statistically significant change (p = 0.6878). On the other hand, the area of inferior turbinate (area 2) decreased significantly compared to preoperative value (p = 0.0021), while the area 3, the area medial to inferior turbinate was widened 1.5 times postoperatively. The total preoperative NOSE score was moderate (39.58 ± 22.31%) and it was decreased to mild (5.83 ± 8.81%) after the treatment (p <0.0001).

CONCLUSIONS

The Swing door compressive fracture (SDCF) technique for turbinoplasty is an effective and straightforward modality. However, the further study involving more patients and longer follow-up period is mandatory.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Identifying Obstructive Sleep Apnoea in Patients with Empty Nose Syndrome

Obstructive sleep apnoea (OSA) is characterised by repetitive episodes of upper airway collapse and breathing cessation during sleep. Empty nose syndrome (ENS) is a surgically iatrogenic phenomenon of paradoxical nasal obstruction despite an objectively patent nasal airway. This study aimed to investigate sleep quality and the presence of OSA in ENS patients. Forty-eight ENS patients underwent full-night polysomnography. Total nasal resistance (TNR) was determined using anterior rhinomanometry. Symptoms and quality of life were evaluated by the empty nose syndrome 6-item questionnaire (ENS6Q), Sino-Nasal Outcome Test-22 (SNOT-22), and Epworth Sleepiness Scale questionnaires (ESS). Fourteen, twelve, and fourteen patients had mild, moderate, and severe OSA, respectively. The apnoea–hypopnoea index (AHI) and the lowest SpO₂ were 23.8 ± 22.4/h and 85.9 ± 11.1%, respectively. N1, N2, N3 and rapid-eye-movement sleep comprised 30.2 ± 16.9%, 47.3 ± 15.5%, 2.1 ± 5.4%, and 20.0 ± 8.1% of the total sleep time. Body mass index, neck circumference, serum total immunoglobulin E, and ENS6Q score were significantly associated with AHI in the regression analysis. The ENS6Q scores correlated positively with AHI, arousal index, and ESS score, but negatively with TNR. ENS patients showed a high OSA prevalence and significant sleep impairment. The extent of OSA was associated with obesity levels and ENS symptom severity. The ENS6Q scores correlated negatively with nasal resistance, and positively with arousal frequency and daytime sleepiness. The recognition of individuals experiencing marked OSA and provision of appropriate intervention is critical to preventing long-term morbidity and mortality, and improving therapeutic outcomes in ENS patients.

Anosmia following middle nasal concha resection: an anatomic and developmental review with clinical correlation

Losing the sense of smell can be associated with a significant decrease in quality of life. Fortunately, this occurs infrequently with modern paranasal sinus surgery that has stressed minimally invasive, tissue-sparing principles. However, over time, more extensive surgical applications have emerged that incorporate increased tissue removal. Post-operative period sequelae can occur, including anosmia. Understanding the potential implications of expanded tissue removal, such as middle nasal concha (turbinate) resection, is clinically important and is facilitated by an understanding of anatomy. Our understanding of anatomic nuances is enhanced through an appreciation of embryonic and fetal development. We herein review the developmental anatomy of the middle nasal concha of the ethmoid sinus and olfactory nerve area as it relates to middle nasal concha removal during endoscopic sinus surgery. We present images from our analysis of twelve embryonic and fetal specimens that highlight the important relationship between the middle nasal concha and olfactory nerves. We also review the clinical issues surrounding turbinate preservation versus resection and present a clinical correlation to underscore the uncommon but significant complication of anosmia following sinus surgery with middle nasal concha resection. We highlight knowledge gaps, discuss case selection and review surgical technique modifications for middle nasal concha surgery to reduce the chance of this complication in the future. This article is protected by copyright. All rights reserved.

Clinical perspectives on nasopharyngeal morphology in humans

The nasopharynx is an integral component of the upper aerodigestive tract, whose morphologic features share an intimate relationship with a vast array of clinical, functional, and quality of life conditions related to contemporary humans. Its composite architecture and central location amidst the nasal cavity, pharyngotympanic tube, palate, and skull base bears implications for basic physiologic functions including breathing, vocalization, and alimentation. Over the course of evolution, morphological modifications of nasopharyngeal anatomy have occurred in genus Homo which serve to distinguish the human upper aerodigestive tract from that of other mammals. Understanding of these adaptive changes from both a comparative anatomy and clinical perspective offers insight into the unique blueprint which underpins many clinical pathologies currently encountered by anthropologists, scientists, and otorhinolaryngologists alike. This discussion intends to familiarize readers with the fundamental role that nasopharyngeal morphology plays in upper aerodigestive tract conditions, with consideration of its newfound clinical relevance in the era of the COVID-19 pandemic.

Double pedicled nasoseptal flap for skull base repair after endoscopic expanded endonasal approach

BACKGROUND

Expanded endonasal approach offers a spectacular corridor for skull base tumour resection but requires reliable multilayer reconstruction techniques with a vascularized nasoseptal flap.

METHOD

On the basis on our substantial experience of 136 patients operated on between January 2008 and January 2020, the double pedicled nasoseptal flap technique was developed for skull base repair. The technique is finely detailed. The nasal floor mucosa was preserved. CSF leakage occurred in 4% of patients.

CONCLUSION

Double pedicled nasoseptal flap is a reproducible and efficient technique for skull base reconstruction after expanded endonasal approach and is associated with limited rhinological complications.

Wet surface wall model for latent heat exchange during evaporation

Air conditioning is a dual heat and mass transfer process, and the human nasal cavity achieves this through the mucosal wall surface, which is supplied with an energy source through the sub-epithelial network of capillaries. Computational studies of air conditioning in the nasal cavity have included temperature and humidity, but most studies solved these flow parameters separately, and in some cases, a constant mucosal surface temperature was used. Recent developments demonstrated that both heat and mass transfer need to be modeled. This work expands on existing modeling efforts in accounting for the nasal cavity's dual heat and mass transfer process by introducing a new subwall model, given in the Supplementary Materials. The model was applied to a pipe geometry, and a human nasal cavity was recreated from CT-scans, and six inhalation conditions were studied. The results showed that when the energy transfer from the latent heat of evaporation is included, there is a cooling effect on the mucosal surface temperature.

Adjunctive Middle Turbinectomy for Endoscopic Medial Orbital Wall – Thyroid Eye Disease Decompression

Introduction Middle turbinate resection (MTR) is commonly performed during endonasal endoscopic sinus and skull base surgery.

Objective The purpose of this study was to characterize the additional orbital soft-tissue volume expansion during endoscopic medial orbital wall decompression with adjunctive MTR.

Methods A retrospective review of patients who underwent endoscopic medial wall decompression with MTR was performed. The imaging software AW (GE Healthcare, Chicago, IL, USA) was used to overlay pre and postoperative orbital computed tomography (CT) images to visualize the preoperative position of the middle turbinate and the postoperative orbital soft tissue in the ethmoid bed. The imaging software Vitrea (Vital Images Inc., Minnetonka, MN, USA) was used to manually segment postoperative scans to determine the volume of orbital tissue which had filled the space previously occupied by the middle turbinate or medial to it.

Results Nine orbits from 5 patients were included in this study; all patients were female with a history of hyperthyroidism. The average age was 55.6 years (range 32–74). Of the 9 orbits, 7 (78%) had orbital soft tissue within the space of the resected middle turbinate postoperatively. The average volume of orbital tissue within or medial to this space was 0.83 +/− 0.67 cc. No patients had any postoperative complications.

Conclusions In this patient cohort, adjunctive middle turbinate resection for endoscopic medial orbital wall decompression added ∼ 0.83 cc of volume for orbital soft tissue after medial wall decompression. Middle turbinate resection is a useful adjunct to the orbital surgeon's armamentarium to augment the results of a medial orbital decompression for select patients.

Evaluation of nasal function after endoscopic endonasal surgery for pituitary adenoma: a computational fluid dynamics study

OBJECTIVE

To analyze the effect of different endoscopic endonasal approaches (EEAs) on nasal airflow and heating and humidification in patients with pituitary adenoma (PA) by computational fluid dynamics (CFD).

METHODS

A three-dimensional pre-surgical model (Pre) of the nasal cavity and 6 that were post-EEA surgery were created from computed tomography scans as follows: small posterior septectomy (0.5 cm, sPS), middle posterior septectomy (1.5 cm, mPS), large posterior septectomy (2.5 cm, lPS), and sPS with middle turbinate resection (sPS-MTR), mPS-MTR, and lPS-MTR. Simulations were performed by CFD to compare the changes in different models.

RESULTS

The temperature in the nasal vestibule rose more rapidly than in other parts of the nasal cavities in all models. There were no apparent differences in temperature and humidity among the models in sections anterior to the middle turbinate head (C6 section). MTR significantly influenced airflow distribution between the bilateral nasal cavities and the different parts of the nasal cavity, while changes in temperature and humidity in each section were mainly affected by MTR. The temperature and humidity of the choana and nasopharynx of each postoperative model were significantly different from those of the preoperative model and the change in values significantly correlated with the surface-to-volume ratio (SVR) of the airway.

CONCLUSIONS

Changes due to the different nasal structures caused different effects on nasal function following the use of EEA surgery for the treatment of PA. CFD provided a new approach to assess nasal function, promising to provide patients with individualized preoperative functional assessment and surgical planning.

Empty Nose Syndrome Pathophysiology: A Systematic Review

OBJECTIVE

The pathophysiology of empty nose syndrome (ENS) remains unclear despite significant research. The pathophysiologic mechanism of ENS was systematically reviewed.

DATA SOURCES

MEDLINE and Embase.

REVIEW METHODS

Data were systematically reviewed for studies that provided original data on pathophysiology.

RESULTS

A total of 2476 studies were screened, and 19 met the inclusion criteria: 13 case-control and 6 cross-sectional. Nine pathophysiologic themes were identified.• Demographics: ENS symptoms had no relationship with climatic factors.• Symptomatology: ENS patients demonstrated high symptom severity.• Mental health: Anxiety and depression including hyperventilation were reported in >50% of ENS patients and correlated with ENS symptom severity.• Anatomic features: Structural changes in response to turbinate surgery were similar between ENS and non-ENS patients.• Airflow analysis: Airflow parameters were similar between ENS and non-ENS patients after turbinate surgery. On computational fluid dynamic analysis, differences were found on multiple outcomes.• Diagnostic testing: The menthol detection test was impaired in ENS, and cotton placement in the airway improved ENS symptoms.• Cognitive function: Functional magnetic resonance imaging showed activation in emotional processing area during breathing.• Olfactory function: Subjective impairment was reported in ENS, but quantitative measures were similar to non-ENS patients.• Mucosal physiology/innate immunity: Turbinate histopathology in ENS showed a tissue-remodeling pattern. Nasal nitric oxide level was lower in ENS patients.

CONCLUSION

There is evidence of high comorbid mental health disorders in ENS patients. An abnormal trigeminal-thermoreceptor response may be present in some patients. The influence of altered airflow and the evidence of surgery as the cause for ENS are unclear.

Inhalation and deposition of spherical and pollen particles after middle turbinate resection in a human nasal cavity

Middle turbinate resection significantly alters the anatomy and redistributes the inhaled air. The superior half of the main nasal cavity is opened up, increasing accessibility to the region. This is expected to increase inhalation dosimetry to the region during exposure to airborne particles. This study investigated the influence of middle turbinate resection on the deposition of inhaled pollutants that cover spherical and non-spherical particles (e.g. pollen). A computational model of the nasal cavity from CT scans, and its corresponding post-operative model with virtual surgery performed was created. Two constant flow rates of 5 L/min, and 15 L/min were simulated under a laminar flow field. Inhaled particles including pollen (non-spherical), and a spherical particle with reference density of 1000 kg/m³ were introduced in the surrounding atmosphere. The effect of surgery was most prominent in the less patent cavity side, since the change in anatomy was proportionally greater relative to the original airway space. The left cavity produced an increase in particle deposition at a flow rate of 15 L/min. The main particle deposition mechanisms were inertial impaction, and to a lesser degree gravitational sedimentation. The results are expected to provide insight into inhalation efficiency of different aerosol types, and the likelihood of deposition in different nasal cavity surfaces.

Middle turbinate resection is unlikely to cause empty nose syndrome in first year postoperatively

PURPOSE

Empty nose syndrome (ENS) is characterized by nasal dryness, crusting, and paradoxical nasal obstruction most commonly after inferior turbinate resection. ENS has also been reported to occur after middle turbinate resection (MTR), and concern for causing ENS is a possible reason surgeons preserve the MT during endoscopic sinus surgery (ESS). The objective was to determine whether MTR during ESS led to ENS.

MATERIALS AND METHODS

This was a prospective case series of 95 consecutive patients that underwent bilateral subtotal MTR during ESS with either Draf IIB or Draf III frontal sinusotomies, for chronic rhinosinusitis with or without nasal polyps, and frontal sinus inverted papillomas. Demographic data and postoperative Empty Nose Syndrome 6-item Questionnaire (ENS6Q) scores were obtained. Nasal crusting was also documented on last postoperative nasal endoscopy.

RESULTS

Pathologies included chronic rhinosinusitis with nasal polyps (69), without nasal polyps (12), and inverted papillomas (14). Fifty-six patients underwent subtotal MTRs during ESS with Draf IIB, and 39 with Draf III. Mean follow-up was 19.4 months (range 12-49). Mean postoperative ENS6Q score was 2.1. Only 2.1% had ENS6Q scores ≥ 11, and 6.3% had nasal crusting at last follow-up. None of the patients with ENS6Q scores ≥ 11 had nasal crusting at last follow-up. There were no significant differences in outcomes between ages, genders, surgery types, or pathologies.

CONCLUSIONS

Patients who underwent bilateral subtotal MTR during ESS were unlikely to develop ENS by at least 1 year postoperatively, based on patients rarely experiencing ENS6Q scores ≥ 11 or persistent nasal crusting.

Nasal air conditioning following total inferior turbinectomy compared to inferior turbinoplasty - A computational fluid dynamics study

BACKGROUND

The aim of this study was to use computational fluid dynamics (CFD) to investigate the effects on nasal heat exchange and humidification of two different surgical techniques for reducing the inferior turbinate under different environmental conditions.

METHODS

Virtual surgery using two techniques of turbinate reduction was performed in eight nasal airway obstruction patients. Bilateral nasal airway models for each patient were compared: 1) Pre-operative 2) Post inferior turbinoplasty 3) Post total inferior turbinate resection (ITR). Two representative healthy models were included. Three different environmental conditions were investigated 1) ambient air 2) cold, dry air 3) hot, humid air. CFD modelling of airflow and conditioning was performed under steady-state, laminar, inspiratory conditions.

FINDINGS

Nasal conditioning is significantly altered following inferior turbinate reduction surgery, particularly with ITR under cold, dry inspired air (CDA). The degree of impairment is minor under the simulated range of environmental conditions (temperature = 12-40 °C; relative humidity = 13-80%). Streams of significantly colder air are found in the nasopharynx and more prevalent under CDA in ITR. These are related to high velocity flow streams, which remain cool in their centre throughout the widened inferior nasal cavity.

INTERPRETATION

Reduced air-mucosal heat exchange and moisture carrying capacity occurs under cooler temperatures in patients following inferior turbinate surgery. The clinical impact in extremely cold and dry conditions in groups with poor baseline respiratory function, respiratory illness, or endurance athletes is of special interest.

Numerical study on the heat-recovery capacity of the human nasal cavity during expiration

The characteristics of the thermal field in the human nasal cavity during the expiration period were investigated using computational fluid dynamics. Heat and water-vapor recovery features were quantitatively investigated under realistic distributions of the epithelial surface and air temperature. A constant expiratory flow rate of 250 mL/s was assumed. The epithelial surface temperature was approximately 34.3-34.4 °C in the nasopharynx and 33.5-33.6 °C in the vestibule region, and these values are in good agreement with the measurement data in the literature. We observed that heat-recovery from the exhaled air mostly occurred in the posterior turbinate region, and the amount of heat recovered is estimated to be approximately 1/3 of the heat supply during inspiration. Because of this heat transfer from the exhaled air to the epithelial surface, the temperature of the epithelial surface increased in this region, and the exhaled air temperature dropped through the turbinate airway. Water-vapor recovery primarily occurs in the posterior segments of the turbinates; however, the amount of water-vapor transfer was approximately 1/5 of that in inspiration. Accordingly, the relative humidity of the exhaled air remained constant throughout the airway.

Modified Posterior Pedicle Middle Turbinate Flap: An Additional Option for Skull Base Resurfacing

OBJECTIVES/HYPOTHESIS

Although the Hadad-Bassagusteguy flap represents the first choice for middle and posterior skull base reconstruction and coverage of exposed bony areas, in some cases it is unavailable. The aim of this study is to describe, as an alternative option in selected cases, a modified posterior pedicle middle turbinate flap (mPPMTF) extended to the lacrimal area. Anatomical features, step-by-step harvesting technique, and surgical applications are presented.

STUDY DESIGN

Anatomic dissection study and case report.

METHODS

Four mPPMTFs were raised in two fresh-frozen cadaver heads. A study of the vascular supply and measurements of length, width, and area of the flap were performed. The ability of the flap to cover the ventral skull base, particularly the upper clivus area, was tested. A clinical case in which an mPPMTF was used for clivus resurfacing after osteoradionecrosis is reported.

RESULTS

The vascular supply of the mPPMTF was identified as the middle turbinate branch of the sphenopalatine artery. The flap had a mean length of 6.92 cm, mean maximum width of 1.08 cm, and mean total area of 5.33 cm² . The flap was able to reach the upper clivus, with a clival coverage ratio of 70.66%. In the clinical case, good surgical outcomes were observed, with accelerated re-epithelization without complications.

CONCLUSIONS

The mPPMTF represents an alternative to the Hadad-Bassagusteguy flap for posterior cranial fossa and nasopharynx resurfacing. The main drawbacks are its technically demanding and time-consuming harvesting.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E767-E774, 2021.

Study of the Anatomical Structure of the Nasopharyngeal Cavity and Distribution of the Air Flow Field

To build a biomechanical numerical model of the nasopharynx, construct an accurate computerized numerical description of its specific anatomical structures, analyze the distribution of air flow field, starting with the anatomical structure of the pharyngeal recess, correlate its anatomical characteristics with the occurrence and development of nasopharyngeal carcinoma from the perspective of biomechanics. In this study, the nasal and nasopharyngeal cavities of healthy male adult, with the pharyngeal recess in an open state, were scanned by CT to obtain DICOM imaging data. Then, they were imported into Mimics 20.0 to build a model which was recorded in binary STL format. Each file was imported into Geomagic studio 12.0 to construct a 3D model saved in an IGES format. Then, it was imported into ANSYS Workbench for numerical simulation of air flow field. The authors found that:Above all, the causes and pathogenesis of nasopharyngeal carcinoma can be identified from the perspective of biomechanics through the construction of a 3D model and analysis of the characteristics of air flow field. With more in-depth research, it is expected that a more solid scientific foundation will be created for related quantitative analysis.

Prelacrimal approach vs conventional surgery for inverted papilloma in the maxillary sinus

BACKGROUND

The prelacrimal approach, termed endoscopic modified medial maxillectomy (EMMM), has recently been applied for treatment of inverted papilloma (IP) in the maxillary sinus. EMMM provides wider access to the maxillary sinus while preserving the inferior turbinate and nasolacrimal duct.

METHODS

We reviewed patients with IP in the maxillary sinus to compare the surgical results obtained by conventional surgery (ie, endoscopic maxillary sinus antrostomy or in combination with the Caldwell-Luc approach) with those obtained by EMMM.

RESULTS

All patients had a T3 on the Krouse staging system, and the average follow-up time was 46.0 months. Of the 18 patients in the conventional group, recurrence was seen in 3 patients (16.6%). No recurrence was seen in the 27 patients who showed preservation of the inferior turbinate and nasolacrimal duct, and no complications occurred in the EMMM group.

CONCLUSIONS

EMMM is an effective surgical approach that reduces recurrence with fewer complications.

Extended endoscopic approaches to the maxillary sinus

OBJECTIVES

Treatment of inflammatory and neoplastic disease in the maxillary sinus, pterygopalatine and infratemporal fossae requires appropriate surgical exposure. As modern rhinology evolves, so do the techniques available. This paper reviews extended endoscopic approaches to the maxillary sinus and the evidence supporting each technique.

METHODS

A literature search of the Ovid Medline and PubMed databases was performed using appropriate key words relating to endoscopic approaches to the maxillary sinus.

RESULTS

Mega-antrostomy and medial maxillectomy have a role in the surgical treatment of refractory inflammatory disease and sinonasal neoplasms. The pre-lacrimal fossa approach provides excellent access but can be limited because of anatomical variations. Both the transseptal and endoscopic Denker's approaches were reviewed; these appear to be associated with morbidity, without any significant increase in exposure over the afore-described approaches.

CONCLUSION

A range of extended endoscopic approaches to the maxillary sinus exist, each with its own anatomical limitations and potential complications.

Distinct Histopathology Characteristics in Empty Nose Syndrome

OBJECTIVES/HYPOTHESIS

Empty nose syndrome (ENS) is a controversial disorder and the change of histopathology has never been discussed. This study aimed to conduct a structured histological review to improve the diagnosis and understanding of ENS. Further immunohistochemical staining of transient receptor potential channel melastatin 8 (TRPM8) was performed.

STUDY DESIGN

A prospective case-control study in a tertiary medical center.

METHODS

Consecutive patients with ENS who were diagnosed and received surgical intervention after failure of conservative management were included. Patients with benign pituitary gland tumor receiving transsphenoidal excision were enrolled as control group. Biopsy of inferior turbinate was obtained during surgery for histological review and immunohistochemical staining.

RESULTS

Seventeen patients with ENS and six patients as a control group were established for structured histological review. Patients with ENS presented significantly more squamous metaplasia, a higher rate of submucosal fibrosis, and a lower submucosal gland number grading. Additionally, a unique histological change called goblet cell metaplasia was found in the ENS group. The respiratory epitheliums of ENS were mostly intact with preservation of ciliated cells and goblet cells. The ENS group had a significantly lower expression level of TRPM8.

CONCLUSIONS

The nasal mucosa of ENS experienced some airway remodeling and thermoreceptors downregulation, which contribute to clinical symptoms. The distinct histology of ENS included preserved respiratory epithelium and goblet cell metaplasia, accompanying with characteristics similar to atrophic rhinitis. Biopsy of the inferior turbinate may help diagnose ENS.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E14-E18, 2021.

Management of Postsurgical Empty Nose Syndrome

Empty nose syndrome (ENS) is a controversial condition associated with disruption of nasal airflow caused by excessive loss of turbinate tissue. ENS arises after total or near-total inferior turbinate resection. Patients present with intense fixation on the perception of nasal obstruction. Diagnostic tools to assess for empty nose syndrome include a validated patient questionnaire and the office cotton test. Treatment involves topical moisturization, behavioral/psychiatric assessment/treatment, and surgical reconstruction. Current data show promising long-term efficacy after surgical intervention. Postprocedural ENS is best prevented by minimizing inferior and middle turbinate tissue loss.

Update on empty nose syndrome: disease mechanisms, diagnostic tools, and treatment strategies

PURPOSE OF REVIEW

To discuss the proposed pathophysiology of empty nose syndrome (ENS), summarize and evaluate the role of validated diagnostic tools in the diagnosis of ENS, and review the medical and surgical treatment strategies for patients with ENS.

RECENT FINDINGS

Historically, ENS has been associated with a reduction in nasal turbinate size; new data suggest that impaired trigeminal nerve function may also play a role in the pathophysiology of the disease. The newly validated empty nose syndrome 6 item questionnaires and Cotton test are steps forward to standardize the diagnosis of ENS. Finally, there has been a marked increase in surgical treatment strategies to reconstitute turbinate volume with various implant materials.

SUMMARY

The diagnosis of ENS remains controversial but the last several years have seen a rejuvenation of interest in this disease entity. The validated empty nose syndrome 6 item questionnaires and Cotton test provide a standardized and objective means by which to characterize ENS. Prevention of iatrogenic ENS through avoidance of excessive turbinate reduction remains critical in preventing paradoxical nasal obstruction. Nasal humidification, patient education, and treatment of possible concomitant medical conditions (e.g., depression) constitute first lines of treatment. We support the cautious use of these screening tools as adjuncts to clinical decision-making. Although injectable implants to augment turbinate volume show promise as a therapeutic surgical technique, there is insufficient data to fully support their use at this time.

Numerical simulation of nasal airflows and thermal air modification in newborns

Warming, filtering, and humidification of inspired air are major functions of the upper airway, which can be negatively altered by local disorders or surgical interventions. These functions have not been described in neonates because of ethical and technical problems difficult to solve. Numerical simulations can get around these limitations. The objective of this study was to analyze physiological nasal airflow and thermal distribution using computational fluid dynamics (CFD) techniques in neonates. CT imaging of neonates was collected from the Pediatric Radiology Department of our center. CFD has been used to simulate nasal airflow numerically, with ambient air set at 19 °C, following the recommendations for a neonate's bedroom. Thermal distribution within the nasal cavity was analyzed and coupled with airflow patterns over complete respiratory cycles. Sixteen patients have been included in the study. During inspiration, important air warming is noticed in the first centimeter of the nasal cavity (+ 8 °C at the anterior end of the inferior turbinate). During the expiration phase, the temperature decreases slightly (- 3 °C) between the pharynx and the nostrils. A model with asymmetric nasal fossae showed that nasal obstruction leads to decreased airflow and abnormally high temperatures in the obstructed side (+ 2 °C at the nasal valve, + 4 °C at the choana). According to our results, the nasal valve area is of crucial importance in air warming in neonates, when ambient air is 19 °C, since about 70% of air warming is performed in this area. When needed, surgical interventions should respect the anatomy of this zone and restore normal airflows and warming. Graphical abstract .

An optimization method for surgical reduction of hypertrophied inferior turbinate

Surgical reductions of the hypertrophied inferior turbinate (HIT) can improve nasal obstruction. However, there is currently a lack of personalized and objective methods to guide surgical operations, which results in the excessive or inadequate resection of HIT. In this study, we proposed an optimizing method based on homotopy deformation to determine the resected amount and shape of the tissue by matching the flow resistance in the two nasal passageways. The simulation results obtained using computational fluid dynamics showed that after such an optimization procedure, the most obstructed nasal side could have a similar air flux as the less obstructed side. A 35% and a 56% less tissue resection in the optimizing operation compared to that in the total turbinectomy could well balance the air flow between the two nasal cavities in the simulations for patients 1 and 2 with unilateral nasal obstruction respectively. Compared with the optimization operation, the total turbinectomy made a more aggressive resection of HIT, which could worsen the air conditioning capacity of the nose. A sensitivity test indicated that in the optimization operation, the most constricted region in the nasal cavity should be adequately enlarged. However, more tissue resection than is required for the optimization operation did not improve the flow in the obstructed side strikingly. Simulations of the optimization operation in both nasal cavities for a patient with bilateral nasal obstruction were also performed. The flow rate could reach the normal level and be well balanced in the two sides after such an optimization procedure.

Patient-Reported Outcome Measures and Provocative Testing in the Workup of Empty Nose Syndrome-Advances in Diagnosis: A Systematic Review

Background

The last 5 years have seen a surge of both clinical and scientific interest in empty nose syndrome (ENS). Although ENS is still considered a controversial diagnosis plagued by a lack of standardized diagnostic criteria, ENS is increasingly becoming recognized as a legitimate, physiologic disease entity. As such, it is important for clinicians to understand the most up-to-date diagnostic tools to assess ENS, confirm the diagnosis, and create a more standardized means to counsel these complex patients.

Objective

Contemporary literature review to discuss diagnostic modalities in the evaluation of ENS, in order to introduce evidence-based diagnostic criteria.

Methods

A systematic review was conducted in PubMed and Embase (2013–2019) using the search term “empty nose syndrome” to identify peer-reviewed articles on the topic of ENS. Articles advancing contemporary methods of ENS diagnosis and testing were included. A quality assessment was conducted using The Rational Clinical Examination Levels of Evidence.

Results

The novel development of the Empty Nose Syndrome 6 Questionnaire (ENS6Q) offers the clinician a validated patient-reported outcome measure to supplement history and physical examination. The in-office cotton test, performed by placing an endoscopically directed cotton plug in the site of tissue loss, may help to identify patients who may benefit from turbinate augmentation. Tools such as the sinus computed tomography scan, computational fluid dynamics, and intranasal trigeminal nerve function testing currently have insufficient evidence to support routine use in the workup of ENS. Up to 66% of ENS patients present with comorbid anxiety or depression.

Conclusion

The ENS6Q and cotton test assist in creating a standardized approach to the evaluation of patients suspected of ENS. These instruments should be used as an adjunct, rather than the sole criteria, on which to ascertain the presumptive diagnosis. Patients suspected of ENS should be screened for comorbid psychological dysfunction.

Computational Fluid Dynamics to Evaluate the Effectiveness of Inferior Turbinate Reduction Techniques to Improve Nasal Airflow

Importance

Inferior turbinate reduction (ITR) is a commonly performed procedure for the treatment of nasal obstruction. Which portion of the inferior turbinates should be surgically addressed to improve nasal airflow has yet to be determined.

Objective

To use computational fluid dynamics (CFD) analysis to evaluate the airflow changes after reduction along different portions of the inferior turbinate.

Design, Setting, and Participants

Computed tomographic scans of 5 patients were selected. Seven CFD models were created for each patient: 1 unaltered and 6 various ITRs, including 3 one-third ITRs (anterior, middle, and posterior one-third); 2 two-thirds ITRs (anterior and posterior two-thirds); and 1 full-length ITR model. Total airflow rate and nasal resistance was obtained through CFD analysis, and regression analysis was performed on the increased nasal volume, locations, and nasal resistance for all 5 patients.

Main Outcomes and Measures

Total airflow rate and nasal resistance was obtained through CFD analysis, and regression analysis was performed on the increased nasal volume, locations, and nasal resistance for all 5 patients.

Results

Full ITR over the whole length was consistently most effective to improve nasal airflow and resistance for all 5 patients (2 men and 3 women), adjusted for the volume. Regression analysis showed a strong linear (R2≥0.79) relationship between nasal volume changes and nasal airflow. However, the most effective location of partial turbinate reduction was not consistent among patients. Surprisingly, for some patients, posterior ITRs were more effective than anterior ITRs. The site of most effective partial ITR differed from 1 side to the other even in the same individual.

Conclusions and Relevance

The effectiveness of partial ITR and target location likely depends on individual patient anatomy. The fact that full ITRs were consistently most effective and the linear regression between flow and nasal volume changes may indicate that the entire length of the IT has a functional impact on nasal airflow and resistance.

Level of Evidence

NA.

Review: The role of computational simulation in understanding the postoperative sinonasal environment

Nasal surgery improves symptoms in a majority of patients for whom medical treatment has failed. In rhinosinusitis patients, endoscopic sinus surgery aims to alleviate obstruction and re-establish mucociliary clearance. Surgery alters the structure-function relationship within the nasal passage, which is difficult to assess clinically. Computational modelling has been used to investigate this relationship by simulating air flow and environmental variables inside realistic three-dimensional models of the human nasal airway but many questions remain unanswered and need further investigation. The application of computational models to improve pre-surgical planning and post-surgical treatment may not be currently possible due to the absence of knowledge correlating the model-predicted parameters to physiological variables. Links between these parameters to patient outcomes are yet to be established. This article reviews the recent application of computational modelling to understand the nasal structure-function relationship following surgery in patients with sinusitis and nasal obstruction.

Lin E, Poetker DM, Garcia GJM. Clinical Importance of Nasal Air Conditioning: A Review of the Literature

Background

Nasal air conditioning (ie, heating and humidification of inspired air) is an important function of the nasal cavity. This function may be reduced in cases of aggressive nasal surgery. Future virtual surgery planning tools may be used to design surgical approaches that preserve the nasal air conditioning capacity while decreasing airflow resistance. However, it is unclear whether there is a threshold below which impaired nasal air conditioning is associated with negative health consequences.

Objective

This study aims to review the literature on the clinical impact of reduced nasal air conditioning and its implications for nasal surgery outcomes.

Methods

A literature search was performed on PubMed and Scopus databases for articles that investigated the effect of air temperature and humidity on mucociliary clearance, respiratory epithelial structure, and the prevalence and severity of respiratory diseases.

Results

Inspiration of cold, dry air has direct effects on the respiratory epithelium, such as reduced mucociliary clearance and loss of cilia. Nasal surgeries do inflict some changes to the nasal mucosa and geometry that may result in decreased heating and humidification, but it is unclear how long these effects last. Laryngectomy patients serve as a human model for the absence of nasal air conditioning. The heat and moisture exchangers that many laryngectomy patients wear have been shown to improve lung function and reduce pulmonary symptoms associated with breathing unconditioned air, such as increased coughing and thickened mucus.

Conclusion

Nasal air conditioning is an important mechanism to maintain mucociliary clearance and prevent infection by inhaled pathogens. Preservation of nasal air conditioning capacity should be considered in the implementation of future virtual surgery planning tools. However, a threshold for the onset of negative health consequences due to impaired nasal air conditioning is not yet available.

Functional relevance of computational fluid dynamics in the field of nasal obstruction: A literature review

BACKGROUND

Nasal airway obstruction (nasal obstruction) is a common symptom affecting the quality of life of patients. It can be estimated by patient perception or physical measurements. Computational fluid dynamics (CFD) can be used to analyse nasal ventilation modalities. There is a lack of comparative studies investigating the correlations between CFD variables and patient perception or physical measurements.

OBJECTIVE OF THE REVIEW

Our goal was to define correlations between CFD variables and patient perception and physical measurements. We also aimed to identify the most reliable CFD variable (heat flux, WSS, total pressure, temperature…) characterising nasal breathing perception.

TYPE OF REVIEW

Systematic literature review using PRISMA guidelines.

SEARCH STRATEGY

The selected studies were obtained from the US National Library of Medicine (PubMed) online database, MEDLINE (Ovid), Google Scholar and the Cochrane Library using a combination of MeSH terms (nose, paranasal sinus, fluid dynamics, rhinology) and non-MeSH terms (CFD, nasal airway, nasal airflow, numerical, nasal symptoms). Studies that did not incorporate objective or subjective clinical assessment were excluded.

EVALUATION METHOD

We compared all results obtained by authors regarding CFD variables and assessment of nasal airway obstruction (clinical or physical).

RESULTS

To compare nasal obstruction with CFD variables, most authors use CFD-calculated nasal resistances, airflow, heat flux, wall shear stress, total pressure, velocities and streamlines. We found that heat flux appears to be the CFD variable most closely correlated with patient perception. Total pressure, wall shear stress and velocities are also useful and show good correlations. Correlations between CFD-calculated nasal resistances and patient perception are stronger after correction of the nasal cycle.

CONCLUSIONS

The growing number of CFD studies on the nose has led to a better understanding of nasal obstruction. The clinical interpretation of previously unknown data, such as WSS and heat flux, is opening up new horizons in the understanding of this symptom. Heat fluxes are among the best CFD values correlated with patient perception. More studies need to be performed including temperature and humidity exchanges.

Normative ranges of nasal airflow variables in healthy adults

PURPOSE

Virtual surgery planning based on computational fluid dynamics (CFD) simulations of nasal airflow has the potential to improve surgical outcomes for patients with nasal airway obstruction (NAO). Virtual surgery planning requires normative ranges of airflow variables, but few studies to date have quantified inter-individual variability of nasal airflow among healthy subjects. This study reports CFD simulations of nasal airflow in 47 healthy adults.

METHODS

Anatomically accurate three-dimensional nasal models were reconstructed from cone beam computed tomography scans and used for steady-state inspiratory airflow simulations with a bilateral flowrate of 250 ml/s. Normal subjective sensation of nasal patency was confirmed using the nasal obstruction symptom evaluation and visual analog scale. Healthy ranges for several CFD variables known to correlate with subjective nasal patency were computed, including unilateral airflow, nasal resistance, airspace minimal cross-sectional area (mCSA), heat flux (HF), and surface area stimulated by mucosal cooling (defined as the area where HF > 50 W/m²). The normative ranges were targeted to contain 95% of the healthy population and computed using a nonparametric method based on order statistics.

RESULTS

A wide range of inter-individual variability in nasal airflow was observed among healthy subjects. Unilateral airflow varied from 60 to 191 ml/s, airflow partitioning ranged from 23.8 to 76.2%, and unilateral mCSA varied from 0.24 to 1.21 cm². These ranges are in good agreement with rhinomanometry and acoustic rhinometry data from the literature. A key innovation of this study are the normative ranges of flow variables associated with mucosal cooling, which recent research suggests is the primary physiological mechanism of nasal airflow sensation. Unilateral HF ranged from 94 to 281 W/m², while the surface area stimulated by cooling ranged from 27.4 to 64.3 cm².

CONCLUSIONS

These normative ranges may serve as targets in future virtual surgery planning for patients with NAO.

Review: The role of computational simulation in understanding the postoperative sinonasal environment

Nasal surgery improves symptoms in a majority of patients for whom medical treatment has failed. In rhinosinusitis patients, endoscopic sinus surgery aims to alleviate obstruction and re-establish mucociliary clearance. Surgery alters the structure-function relationship within the nasal passage, which is difficult to assess clinically. Computational modelling has been used to investigate this relationship by simulating air flow and environmental variables inside realistic three-dimensional models of the human nasal airway but many questions remain unanswered and need further investigation. The application of computational models to improve pre-surgical planning and post-surgical treatment may not be currently possible due to the absence of knowledge correlating the model-predicted parameters to physiological variables. Links between these parameters to patient outcomes are yet to be established. This article reviews the recent application of computational modelling to understand the nasal structure-function relationship following surgery in patients with sinusitis and nasal obstruction.

Computational fluid dynamic analysis of aggressive turbinate reductions: is it a culprit of empty nose syndrome?

BACKGROUND

Empty nose syndrome (ENS) remains highly controversial, with aggressive inferior turbinate reduction (ITR) or mucociliary dysfunction frequently implicated. However, the appropriate degree of ITR is highly debatable.

METHODS

We applied individual computed tomography (CT)-based computational fluid dynamics (CFD) to 5 patients receiving relatively aggressive ITR but with no ENS symptoms, and compared them to 27 symptomatic ENS patients who all had histories of aggressive ITRs, and 42 healthy controls. Patients' surgical outcomes were confirmed with 22-item Sino-Nasal Outcome Test (SNOT-22) (ITR: 6.40 ± 4.56; ENS: 58.2 ± 15.9; healthy: 13.2 ± 14.9), Nasal Obstruction Symptom Evaluation (NOSE) scores (ITR: 4.00 ± 2.24; ENS: 69.4 ± 17.1; healthy: 11.9 ± 12.9), and Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) (≥11 for ENS).

RESULTS

Both aggressive ITR without ENS symptoms and symptomatic ENS patients had significantly lower nasal resistance (ITR: 0.059 ± 0.020 Pa·s/mL; ENS: 0.052 ± 0.015 Pa·s/mL; healthy: 0.070 ± 0.021 Pa·s/mL) and higher cross-sectional areas surrounding the inferior turbinate (ITR: 0.94 ± 0.21 cm² ; ENS: 1.19 ± 1.05 cm² ; healthy: 0.42 ± 0.22 cm² ) than healthy controls. The lack of significant differences among patient groups indicated similar degrees of surgeries between ITR with and without ENS symptom cohorts. However, symptomatic ENS patients have paradoxical significantly less airflow in the inferior meatus (ITR: 47.7% ± 23.6%; ENS: 25.8% ± 17.6%; healthy: 36.5 ± 15.9%; both p < 0.01), but higher airflow around the middle meatus (ITR: 49.7% ± 22.6%; ENS: 66.5% ± 18.3%; healthy: 49.9% ± 15.1%, p < 0.0001) than aggressive ITR without symptoms and controls. Aggressive ITR patients have increased inferior meatus airflow as expected (p < 0.05). This imbalanced airflow produced less inferior wall-shear-stress distribution among symptomatic ENS patients only (ITR: 42.45% ± 11.4%; ENS: 32.2% ± 12.6%; healthy: 49.7% ± 9.9%). ENS patients (n = 12) also had impaired nasal trigeminal function, as measured by menthol lateralization detection thresholds (ITR: 15.2 ± 1.2; ENS: 10.3 ± 3.9; healthy: 13.8 ± 3.09, both p < 0.0001). Surprisingly, aggressive ITR patients without ENS symptoms have better menthol lateralization detection thresholds (LDTs) than healthy controls.

CONCLUSION

Although turbinate tissue loss is linked with ENS, the degree of ITR that might distinguish postoperative patient satisfaction in their nasal breathing vs development of ENS symptoms is unclear. Our results suggest that a combination of distorted nasal aerodynamics and loss of mucosal sensory function may potentially lead to ENS symptomology.

Middle Turbinate Friendly Technique for Cribriform Cerebrospinal Fluid Leak Repair

OBJECTIVE

To compare surgical outcomes between 2 techniques for cribriform cerebrospinal fluid leak (CSF) repair with middle turbinate preservation (MTP) vs middle turbinate resection (MTR). A secondary outcome is to examine the effectiveness of collagen dura matrix (CDM) as a grafting material for repair of isolated cribriform skull base defects.

STUDY DESIGN

A retrospective chart review was performed of consecutive patients who underwent cribriform CSF repair at Emory University over the past 15 years.

SETTING

Tertiary care rhinology practice.

SUBJECTS

Adult patients with cribriform defects limited to the cribriform plate that did not extend lateral to the middle turbinate (MT) and were reconstructed with a free graft (mucosal or synthetic).

METHODS

Patients were stratified into 2 primary groups by surgical technique: MTP vs MTR. A subset of patients underwent repair with CDM alone and was analyzed separately for CSF repair failure rate.

RESULTS

Of 68 patients identified with cribriform defects, 42 underwent repair with MTP and 26 underwent repair with MTR. Average follow-up time was 495 days. Patients with idiopathic intracranial hypertension were also equally distributed (P = .20). Primary CSF leak repair success was 95.6%, with 100% of leaks ultimately repaired. A subset of 39 patients underwent repair with CDM alone, with a primary repair success rate of 94.9%.

CONCLUSIONS

We present an effective method for repair of cribriform CSF leaks while preserving the MT. CDM can be successfully used as a free graft alone for repair of isolated cribriform CSF leaks.

Climatic adaptation in human inferior nasal turbinate morphology: Evidence from Arctic and equatorial populations

OBJECTIVES

The nasal turbinates directly influence the overall size, shape, and surface area of the nasal passages, and thus contribute to intranasal heat and moisture exchange. However, unlike the encapsulating walls of the nasal cavity, ecogeographic variation in nasal turbinate morphology among humans has not yet been established. Here we investigate variation in inferior nasal turbinate morphology in two populations from climatically extreme environments.

MATERIALS AND METHODS

Twenty-three linear measurements of the inferior turbinate, nasal cavity walls, and airway passages were collected from CT scans of indigenous modern human crania from Equatorial Africa (n = 35) and the Arctic Circle (n = 35). MANOVA and ANCOVA were employed to test for predicted regional and sex differences in morphology between the samples.

RESULTS

Significant morphological differences were identified between the two regional samples, with no evidence of significant sexual dimorphism or region-sex interaction effect. Individuals from the Arctic Circle possessed superoinferiorly and mediolaterally larger inferior turbinates compared to Equatorial Africans. In conjunction with the surrounding nasal cavity walls, these differences in turbinate morphology produced airway dimensions that were both consistent with functional expectations and more regionally distinct than either skeletal component independently.

CONCLUSION

This study documents the existence of ecogeographic variation in human nasal turbinate morphology reflecting climate-mediated evolutionary demands on intranasal heat and moisture exchange. Humans adapted to cold-dry environments exhibit turbinate morphologies that enhance contact between respired air and nasal mucosa to facilitate respiratory air conditioning. Conversely, humans adapted to hot-humid environments exhibit turbinate morphologies that minimize air-to-mucosa contact, likely to minimize airflow resistance and/or facilitate expiratory heat-shedding.

Impact of endoscopic craniofacial resection on simulated nasal airflow and heat transport

BACKGROUND

Endoscopic craniofacial resections (CFR) are performed for extensive anterior skull base lesions. This surgery involves removal of multiple intranasal structures, potentially leading to empty nose syndrome (ENS). However, many patients remain asymptomatic postoperatively. Our objective was to analyze the impact of CFR on nasal physiology and airflow using computational fluid dynamics (CFD). This is the first CFD analysis of post-CFR patients.

METHODS

Three-dimensional sinonasal models were constructed from 3 postoperative images using Mimics^TM . Hybrid computational meshes were created. Steady inspiratory airflow and heat transport were simulated at patient-specific flow rates using shear stress transport k-omega turbulent flow modeling in Fluent^TM . Simulated average heat flux (HF) and surface area where HF exceeded 50 W/m² (SAHF50) were compared with laminar simulations in 9 radiographically normal adults.

RESULTS

Three adults underwent CFR without developing ENS. Average HF (W/m² ) were 132.70, 134.84, and 142.60 in the CFR group, ranging from 156.24 to 234.95 in the nonoperative cohort. SAHF50 (m² ) values were 0.0087, 0.0120, and 0.0110 in the CFR group, ranging from 0.0082 to 0.0114 in the radiographically normal cohort. SAHF50 was distributed throughout the CFR cavities, with increased HF at the roof and walls compared with the nonoperative cohort.

CONCLUSION

Average HF was low in the CFR group compared with the nonoperative group. However, absence of ENS in most CFR patients may be due to large stimulated mucosal surface area, commensurate with the nonoperative cohort. Diffuse distribution of stimulated area may result from turbulent mixing after CFR. To better understand heat transport post-CFR, a larger cohort is necessary.

A hierarchical stepwise approach to evaluate nasal patency after virtual surgery for nasal airway obstruction

BACKGROUND

Despite advances in medicine and expenditures associated in treatment of nasal airway obstruction, 25-50% of patients undergoing nasal surgeries complain of persistent obstructive symptoms. Our objective is to develop a "stepwise virtual surgery" method that optimizes surgical outcomes for treatment of nasal airway obstruction.

METHODS

Pre-surgery radiographic images of two subjects with nasal airway obstruction were imported into Mimics imaging software package for three-dimension reconstruction of the airway. A hierarchical stepwise approach was used to create seven virtual surgery nasal models comprising individual (inferior turbinectomy or septoplasty) procedures and combined inferior turbinectomy and septoplasty procedures via digital modifications of each subject's pre-surgery nasal model. To evaluate the effects of these procedures on nasal patency, computational fluid dynamics modeling was used to perform steady-state laminar inspiratory airflow and heat transfer simulations in every model, at resting breathing. Airflow-related variables were calculated for virtual surgery models and compared with dataset containing results of healthy subjects with no symptoms of nasal obstruction.

FINDINGS

For Subject 1, nasal models with virtual septoplasty only and virtual septoplasty plus inferior turbinectomy on less obstructed side were within the healthy reference thresholds on both sides of the nasal cavity and across all three computed variables. For Subject 2, virtual septoplasty plus inferior turbinectomy on less obstructed side model produced the best result.

INTERPRETATION

The hierarchical stepwise approach implemented in this preliminary report demonstrates computational fluid dynamics modeling ability to evaluate the efficiency of different surgical procedures for nasal obstruction in restoring nasal patency to normative level.

Impact of Middle Turbinectomy on Airflow to the Olfactory Cleft: A Computational Fluid Dynamics Study

BACKGROUND

The impact of middle turbinate resection (MTR) on olfaction remains a point of debate in the current literature. Few studies have objectively evaluated olfactory cleft airflow following MTR; thus, the mechanism by which MTR may impact olfaction is poorly understood. It is not known whether the postsurgical changes in airway volume, flow, and resistance increase odorant transport or disrupt the patterns of normal airflow. Computational fluid dynamics can be used to study the nasal airway and predict responses to surgical intervention.

OBJECTIVE

To evaluate the functional impact of MTR on nasal airflow, resistance, and olfaction.

METHODS

Five maxillofacial computed tomography scans of patients without signs of significant sinusitis or nasal polyposis were used. Control models for each patient were compared to their corresponding model after virtual total MTR. For each model, nasal airway volume, nasal resistance, and air flow rate were determined. Odorant transport of 3 different odorants in the nasal cavity was simulated based on the computed steady airflow field.

RESULTS

Total airflow significantly increased following bilateral MTR in all patient models ( P < .05). Consistent with our airflow results, we found a decrease in nasal resistance following MTR. MTR significantly increased area averaged flux to the olfactory cleft when compared to controls for phenylethyl alcohol (high-sorptive odorant). Results for carvone (medium sorptive) were similarly elevated. MTR impact on limonene, a low flux odorant, was equivocal.

CONCLUSION

MTR increases nasal airflow while decreasing the nasal resistance. Overall, olfactory flux increased for high sorptive (phenylethyl alcohol) and medium sorpitve (l-carvone) odorants. However, the significant variation observed in one of our models suggests that the effects of MTR on the nasal airflow and the resultant olfaction can vary between individuals based on individual anatomic differences.

Identification of a Novel High Yielding Source of Multipotent Adult Human Neural Crest-Derived Stem Cells

Due to their extraordinarily broad differentiation potential and persistence during adulthood, adult neural crest-derived stem cells (NCSCs) are highly promising candidates for clinical applications, particularly when facing the challenging treatment of neurodegenerative diseases or complex craniofacial injuries. Successful application of human NCSCs in regenerative medicine and pharmaceutical research mainly relies on the availability of sufficient amounts of tissue for cell isolation procedures. Facing this challenge, we here describe for the first time a novel population of NCSCs within the middle turbinate of the human nasal cavity. From a surgical point of view, high amounts of tissue are routinely and easily removed during nasal biopsies. Investigating the presence of putative stem cells in obtained middle turbinate tissue by immunohistochemistry, we observed Nestin⁺/p75^NTR+/S100⁺/α smooth muscle actin (αSMA)^- cells, which we successfully isolated and cultivated in vitro. Cultivated middle turbinate stem cells (MTSCs) kept their expression of neural crest and stemness markers Nestin, p75 ^NTR and S100 and showed the capability of sphere formation and clonal growth, indicating their stem cell character. Application of directed in vitro differentiation assays resulted in successful differentiation of MTSCs into osteogenic and neuronal cell types. Regarding the high amount of tissue obtained during surgery as well as their broad differentiation capability, MTSCs seem to be a highly promising novel neural crest stem cell population for applications in cell replacement therapy and pharmacological research.

Computational fluid dynamics after endoscopic endonasal skull base surgery-possible empty nose syndrome in the context of middle turbinate resection

BACKGROUND

Empty nose syndrome (ENS) is a rare and debilitating disease with a controversial definition, etiology, and treatment. One puzzling fact is that patients who undergo an endoscopic endonasal approach (EEA) often have resection of multiple anatomic structures, yet seldom develop ENS. In this pilot study, we analyzed and compared the computational fluid dynamics (CFD) and symptoms among post-EEA patients, ENS patients, and healthy subjects.

METHODS

Computed tomography scans of 4 post-EEA patients were collected and analyzed using CFD techniques. Two patients had significant ENS symptoms based on results of the Empty Nose Syndrome 6-item Questionnaire (score >11), whereas the other 2 were asymptomatic. As a reference, their results were compared with previously published CFD results of 27 non-EEA ENS patients and 42 healthy controls.

RESULTS

Post-EEA patients with ENS symptoms had a similar nasal airflow pattern as non-EEA ENS patients. This pattern differed significantly from that of EEA patients without ENS symptoms and healthy controls. Overall, groups with ENS symptoms exhibited airflow dominant in the middle meatus region and a significantly lower percentage of airflow in the inferior turbinate region (EEA with ENS, 17.74 ± 4.00% vs EEA without ENS, 51.25 ± 3.33% [t test, p < 0.02]; non-EEA ENS, 25.8 ± 17.6%; healthy subjects, 36.5 ± 15.9%) as well as lower peak wall shear stress (EEA with ENS, 0.30 ± 0.13 Pa vs EEA without ENS, 0.61 ± 0.03 Pa [p = 0.003]; non-EEA ENS, 0.58 ± 0.24 Pa; healthy subjects, 1.18 ± 0.81 Pa).

CONCLUSION

These results suggest that turbinectomy and/or posterior septectomy may have a varying functional impact and that ENS symptoms go beyond anatomy and correlate with aerodynamic changes. The findings open the door for CFD as a potential objective diagnosis tool for ENS.

Inferior Turbinate Swing Technique: A Novel Surgical Route to Approach Maxillary Sinus Area Pathology

The inferior turbinate is an important structure for maintenance of adequate physiologic function within the nasal cavity. However, it hampers access to lesions involving maxillary sinus areas, including postoperative mucocele or benign tumor, and acts as an inferior limit to widening the natural ostium of a maxillary sinus. Here, we introduce a novel technique, interior turbinate swing, to facilitate entry to the inferior meatus or maxillary sinus while maintaining integrity of the inferior turbinate. In this technique, the anterior part of inferior turbinate is cut with sharp scissors, rotated posteriorly, and held in the nasopharynx. The inferior turbinate swing technique was employed in 38 subjects, and no patients exhibited recurrence of the causative disease without complication. Therefore, we may conclude that the inferior turbinate swing technique is a simple, effective, and safe treatment option for the management of postoperative mucocele, maxillary sinusitis with narrow inlet, or benign tumors.

Efficacy and Safety of Autologous Stromal Vascular Fraction in the Treatment of Empty Nose Syndrome

OBJECTIVES

Regenerative treatment using stem cells may serve as treatment option for empty nose syndrome (ENS), which is caused by the lack of turbinate tissue and deranged nervous system in the nasal cavity. We aimed to assess the efficacy and safety of the autologous stromal vascular fraction (SVF) in the treatment of ENS.

METHODS

In this prospective observational clinical study, we enrolled 10 ENS patients who volunteered to undergo treatment of ENS through the injection of autologous SVF. Data, including demographic data, pre- and postoperative Sino-Nasal Outcome Test-25 (SNOT-25) scores, overall patient satisfaction, and postoperative complications, were prospectively collected. Nasal secretion was assessed using the polyurethane foam absorption method, and the levels of biological markers were analyzed in both ENS group and control group using enzyme-linked immunosorbent assay. The SVF extracted from abdominal fat was diluted and injected into both inferior turbinates.

RESULTS

Among the 10 initial patients, one was excluded from the study. Subjective satisfaction was rated as "much improved" in two and "no change" in seven. Among the improved patients, the mean preinjection SNOT-25 score was 55.0 and the score at 6 months after injection was 19.5. However, the average SNOT-25 score of nine participants at 6 months after injection (mean±standard deviation, 62.4±35.8) did not differ significantly from the baseline SNOT25 score (70.1±24.7, P>0.05, respectively). Among the various inflammatory markers assessed, the levels of interleukin (IL)-1β, IL-8, and calcitonin gene-related peptide were significantly higher in ENS patients. Compared with preinjection secretion level, the nasal secretions from SVF-treated patients showed decreased expressions of IL-1β and IL-8 after injection.

CONCLUSION

Although SVF treatment appears to decrease the inflammatory cytokine levels in the nasal mucosa, a single SVF injection was not effective in terms of symptom improvement and patient satisfaction. Further trials are needed to identify a more practical and useful regenerative treatment modality for patients with ENS.

Investigation of the abnormal nasal aerodynamics and trigeminal functions among empty nose syndrome patients

BACKGROUND

Abnormal nasal aerodynamics or trigeminal functions have been frequently implicated in the symptomology of empty nose syndrome (ENS), yet with limited evidence.

METHODS

Individual computed tomography (CT)-based computational fluid dynamics (CFD) was applied to 27 ENS patients to simulate their nasal aerodynamics and compared with 42 healthy controls. Patients' symptoms were confirmed with Empty Nose Syndrome 6-item Questionnaire (ENS6Q), 22-item Sino-Nasal Outcome Test (SNOT-22), and Nasal Obstruction Symptom Evaluation (NOSE) scores. Nasal trigeminal sensitivity was measured with menthol lateralization detection thresholds (LDTs).

RESULTS

ENS patients had significantly lower (∼25.7%) nasal resistance and higher (∼2.8 times) cross-sectional areas compared to healthy controls (both p < 0.001). Despite inferior turbinate reductions, CFD analysis demonstrated that ENS patients had increased airflow concentrated in the middle meatus region (66.5% ± 18.3%) compared to healthy controls (49.9% ± 15.1%, p < 0.0001). Significantly less airflow (25.8% ± 17.6%) and lower peak wall shear stress (WSS) (0.58 ± 0.24 Pa) were found in the inferior meatus (vs healthy: 36.5% ± 15.9%; 1.18 ± 0.81 Pa, both p < 0.05), with the latter significantly correlated with the symptom scores of ENS6Q (r = -0.398, p = 0.003). Item-wise, complaints of "suffocation" and "nose feels too open" were also found to be significantly correlated with peak WSS around the inferior turbinate (r = -0.295, p = 0.031; and r = -0.388, p = 0.004, respectively). These correlations were all negative, indicating that less air-mucosal stimulations resulted in worse symptom scores. ENS patients (n = 12) also had impaired menthol LDT when compared to healthy controls (p < 0.0001).

CONCLUSION

This is the first CFD examination of nasal aerodynamics in a large cohort of ENS patients. The results indicated that a combination of loss of neural sensitivity and poorer inferior air-mucosal stimulation may potentially lead to ENS symptomology.

Numerical simulation of two consecutive nasal respiratory cycles: toward a better understanding of nasal physiology

BACKGROUND

Computational fluid dynamic (CFD) simulations have greatly improved the understanding of nasal physiology. We postulate that simulating the entire and repeated respiratory nasal cycles, within the whole sinonasal cavities, is mandatory to gather more accurate observations and better understand airflow patterns.

METHODS

A 3-dimensional (3D) sinonasal model was constructed from a healthy adult computed tomography (CT) scan which discretized in 6.6 million cells (mean volume, 0.008 mm³ ). CFD simulations were performed with ANSYS©FluentTMv16.0.0 software with transient and turbulent airflow (k-ω model). Two respiratory cycles (8 seconds) were simulated to assess pressure, velocity, wall shear stress, and particle residence time.

RESULTS

The pressure gradients within the sinus cavities varied according to their place of connection to the main passage. Alternations in pressure gradients induced a slight pumping phenomenon close to the ostia but no movement of air was observed within the sinus cavities. Strong movements were observed within the inferior meatus during expiration contrary to the inspiration, as in the olfactory cleft at the same time. Particle residence time was longer during expiration than inspiration due to nasal valve resistance, as if the expiratory phase was preparing the next inspiratory phase. Throughout expiration, some particles remained in contact with the lower turbinates. The posterior part of the olfactory cleft was gradually filled with particles that did not leave the nose at the next respiratory cycle. This pattern increased as the respiratory cycle was repeated.

CONCLUSION

CFD is more efficient and reliable when the entire respiratory cycle is simulated and repeated to avoid losing information.

Aerodynamic evaluation of the empty nose syndrome by means of computational fluid dynamics

The potential outcome of a surgical enlargement of internal nasal channels may be a complication of nasal breathing termed the Empty Nose Syndrome (ENS). ENS pathophysiology is not entirely understood because the expansion of air pathways would in theory ease inhalation. The present contribution is aimed at defining the biophysical markers responsible for ENS. Our study, conducted in silico, compares nasal aerodynamics in pre- and post-operative geometries acquired by means of computer tomography from the same individual. In this article, we elucidate and analyse the deviation of airflow patterns and nasal microclimate from the healthy benchmarks. The analysis reveals 53% reduction in flow resistance, radical re-distribution of nasal airflow, as well as dryer and colder nasal microclimate for the post-operative case.

Surgical outcome for empty nose syndrome: Impact of implantation site

OBJECTIVE/HYPOTHESIS

Endonasal submucosal implantation has been confirmed to be beneficial for patients with empty nose syndrome (ENS). However, the optimal implantation site has not been defined. This study aimed to evaluate whether lateral nasal wall implantation is superior to inferior nasal wall implantation in terms of clinical benefits and improvements in quality of life.

STUDY DESIGN

Retrospective study in a tertiary medical center.

METHODS

Consecutive ENS patients between 2010 and 2015 with operative histories of inferior turbinectomies and indicated for surgical implantation were enrolled, with at least 1-year follow-up. Patients were divided into lateral and inferior nasal wall groups. SinoNasal Outcome Test (SNOT)-22, Beck Depression Inventory (BDI)-II, and Beck Anxiety Inventory (BAI) were applied before and 1 year after implantation.

RESULTS

Of the total 30 ENS patients analyzed, 14 were in the inferior nasal wall group and 16 were in the lateral nasal wall group. There were no significant intergroup differences in demographic data and preoperative SNOT-22, BDI-II, and BAI scores. Postoperative assessment revealed that the lateral nasal wall group had significantly better SNOT-22 score improvements than the inferior nasal wall group, particularly regarding rhinological symptoms and sleep function.

CONCLUSION

Lateral nasal wall implantation may provide significantly better clinical outcomes than inferior nasal wall implantation, and thus may be the preferred, more optimal site for implant placement in ENS patients.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:554-559, 2018.

Correlation of Nasal Mucosal Temperature With Subjective Nasal Patency in Healthy Individuals

Importance

Historically, otolaryngologists have focused on nasal resistance to airflow and minimum airspace cross-sectional area as objective measures of nasal obstruction using methods such as rhinomanometry and acoustic rhinometry. However, subjective sensation of nasal patency may be more associated with activation of cold receptors by inspired air than with respiratory effort.

Objective

To investigate whether subjective nasal patency correlates with nasal mucosal temperature in healthy individuals.

Design, Setting, and Participants

Healthy adult volunteers first completed the Nasal Obstruction Symptom Evaluation (NOSE) and a unilateral visual analog scale to quantify subjective nasal patency. A miniaturized thermocouple sensor was then used to record nasal mucosal temperature bilaterally in 2 locations along the nasal septum: at the vestibule and across from the inferior turbinate head.

Main Outcomes and Measures

Nasal mucosal temperature and subjective patency scores in healthy individuals.

Results

The 22 healthy adult volunteers (12 [55%] male; mean [SD] age, 28.3 [7.0] years) had a mean (SD) NOSE score of 5.9 (8.4) (range, 0-30) and unilateral VAS score of 1.2 (1.4) (range, 0-5). The range of temperature oscillations during the breathing cycle, defined as the difference between end-expiratory and end-inspiratory temperatures, was greater during deep breaths (mean [SD] change in temperature, 6.2°C [2.6°C]) than during resting breathing (mean [SD] change in temperature, 4.2°C [2.3°C]) in both locations (P < .001). Mucosal temperature measured at the right vestibule had a statistically significant correlation with both right-side visual analog scale score (Pearson r = -0.55; 95% CI, -0.79 to -0.17; P = .008) and NOSE score (Pearson r = -0.47; 95% CI, -0.74 to -0.06; P = .03). No other statistically significant correlations were found between mucosal temperature and subjective nasal patency scores. Nasal mucosal temperature was lower (mean of 1.5°C lower) in the first cavity to be measured, which was the right cavity in all participants.

Conclusions and Relevance

The greater mucosal temperature oscillations during deep breathing are consistent with the common experience that airflow sensation is enhanced during deep breaths, thus supporting the hypothesis that mucosal cooling plays a central role in nasal airflow sensation. A possible correlation was found between subjective nasal patency scores and nasal mucosal temperature, but our results were inconsistent. The higher temperature in the left cavity suggests that the sensor irritated the nasal mucosa, affecting the correlation between patency scores and mucosal temperature. Future studies should consider noncontact temperature sensors to prevent mucosa irritation.

Level of Evidence

NA.