Embryology of the nose: The evo-devo concept

Critical review of diagnosis in rhinology and its therapeutical implications

Diagnosis in rhinology is currently based on the concept of inflammation (chronic rhinosinusitis [CRS]) or the clinical concept of chronic nasal dysfunction (CND). The complementarity between these two approaches can be discussed by a critical review of the literature structured by the analysis of the fundamental and diagnostic bases and the therapeutic implications linked to each. The concept of CRS is based on the anatomical continuity of the nasal and sinus respiratory mucosa and molecular biology data, seeking to analyze the mechanisms of chronic inflammation and to identify proteins and biomarkers involved in the different supposed endotypes of chronic inflammation of this mucosa. The concept of CND seeks to analyze medical, instrumental or surgical diagnostic and therapeutic strategies, taking account of both inflammatory and non-inflammatory causes impacting the anatomy or physiology of each of the three noses (olfactory, respiratory and sinus) that make up the mid-face sinonasal organ of evolution-development (Evo-Devo) theory. Thus, the concept of CRS offers an endotypic approach, based on biological characterization of mucosal inflammation, while the concept of CND offers a compartmentalized phenotypic and pathophysiological approach to sinonasal diseases. The joint contribution of these two concepts in characterizing nasal functional pathology could in future improve the medical service provided to 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.

Do the upper lateral nasal cartilages exist? The concept of septolateral cartilages

BACKGROUND

In the cartilaginous nose, classical surgical anatomy describes 2 triangular upper lateral cartilages (ULCs) framing the lateral sides of the mid-third of the nasal pyramid, which articulate with to the superior edge of the quadrangular cartilage (QC) of the nasal septum. This anatomic arrangement in 3 distinct cartilage parts is, however, controversial.

OBJECTIVE

The present study aimed to describe the articulation between the ULCs and the QC, avoiding dissection artefacts.

MATERIALS AND METHODS

Six nasal pyramids were taken in monobloc from fresh cadavers and imaged on micro-MRI with 0.4mm slice thickness. Images were interpreted jointly by 2 head and neck surgeons and a radiologist.

RESULTS

The cartilage skeleton supporting the mid-third of the nasal dorsum in all specimens presented as 2 septal plates backing onto the midline and curving on either side to form a continuous dome under the inferior aspect of the piriform aperture.

CONCLUSION

Like the alar cartilages framing the tip of the nose, there are two continuous septolateral cartilages (SLCs) framing the mid-third of the nasal pyramid, likewise showing 2 cruras, medial and lateral, joined in a dome. The SLCs (also known as triangular cartilages) thus cannot be separated as 2 individual anatomic structures. These findings are in line with the shared embryological origin of all the elements composing the fibrocartilaginous nose in evo-devo theory.

Septorhinoplasty by disarticulation

Septorhinoplasty by disarticulation is an esthetic and functional solution for naturally occuring nasal pyramid dysmorphia, releasing the anatomic traces of growth-related stresses. Disarticulating the septolateral cartilage from its bony framework via a closed approach to the septal pocket is associated to Rethi's external approach in order to disarticulate the fibrocartilaginous nasal dorsum, while conserving its integrity, under the bony dorsum. The bony pyramid is then disarticulated down to the nasion, after resecting any bone hump, by 2 paramedian and 2 low lateral osteotomies in the basal groove. The lateral sides of the bony pyramid are then fractured at their posterior edges by percutaneous pinching to close the open roof and realign them along the midline. The septolateral cartilage, reduced as necessary at the inferior and anterior edges, is thereafter repositioned on the premaxillary bone. Traction on its anterior edge restores rectilinear frontal and lateral tension in the fibrocartilaginous dorsum, fully conserved from its attachment to the nasion. This technique corrects any septal deformity and restores frontal and lateral dorsum straightness.

Extracellular Matrix Composition and Remodeling: Current Perspectives on Secondary Palate Formation, Cleft Lip/Palate, and Palatal Reconstruction

Craniofacial development comprises a complex process in humans in which failures or disturbances frequently lead to congenital anomalies. Cleft lip with/without palate (CL/P) is a common congenital anomaly that occurs due to variations in craniofacial development genes, and may occur as part of a syndrome, or more commonly in isolated forms (non-syndromic). The etiology of CL/P is multifactorial with genes, environmental factors, and their potential interactions contributing to the condition. Rehabilitation of CL/P patients requires a multidisciplinary team to perform the multiple surgical, dental, and psychological interventions required throughout the patient's life. Despite progress, lip/palatal reconstruction is still a major treatment challenge. Genetic mutations and polymorphisms in several genes, including extracellular matrix (ECM) genes, soluble factors, and enzymes responsible for ECM remodeling (e.g., metalloproteinases), have been suggested to play a role in the etiology of CL/P; hence, these may be considered likely targets for the development of new preventive and/or therapeutic strategies. In this context, investigations are being conducted on new therapeutic approaches based on tissue bioengineering, associating stem cells with biomaterials, signaling molecules, and innovative technologies. In this review, we discuss the role of genes involved in ECM composition and remodeling during secondary palate formation and pathogenesis and genetic etiology of CL/P. We also discuss potential therapeutic approaches using bioactive molecules and principles of tissue bioengineering for state-of-the-art CL/P repair and palatal reconstruction.

Thermal water delivery in the nose: experimental results describing droplet deposition through computational fluid dynamics

Thermal water therapies have a role in treating various inflammatory disorders dating back to ancient Greece. Several studies have demonstrated beneficial effects of thermal water inhalations for upper respiratory disorders, such as improvement of mucociliary function and reduction of inflammatory cell infiltration. This experimental study describes the numerical investigation and clinical implications of thermal water droplet deposition in the nasal cavity of a single patient. To our knowledge, the numerical flow simulations described are the first investigations specifically designed for thermal water applications. To simulate nasal airflow, a patient-specific 3D computer model was created from a CT scan. The numerical approach is based on the Large Eddy Simulation (LES) technique and builds entirely upon open-source software. Deposition on mucosa was studied for two droplet sizes (5 and 10 μm diameter), corresponding to common thermal therapy applications (aerosol and vapour inhalation). The simulations consider steady inspiration at two different (low and moderate) breathing intensities. The results of this preliminary study show specific deposition patterns that favour droplet deposition in the middle meatus region to the inferior meatus, with particle size- and breathing intensity-related effects. These global data on particle deposition differ from findings related to the single-phase nasal airflow, which is more evenly distributed between the middle and inferior meatus. The potential clinical consequences of deposition data are discussed. The study furthermore provides evidence for the effectiveness of thermal aerosol and vapour inhalation therapies in reaching important areas of nasal mucosa with considerable clinical significance.

Analysis of the development of human foetal nasal turbinates using CBCT imaging

PURPOSE

The morphological structure of the nasal cavity (NC) is important for endoscopic surgical treatment. The location of nasal turbinates, including the superior turbinate (ST), middle turbinate (MT) and inferior turbinate (IT), are well presented during the formation of the human NC in cone beam CT (CBCT) images. There is a complex relationship between the nasal sinuses, the maxillary sinus (MS), ethmoidal sinus and sphenoid sinus, during formation of the NC structure at the morphological level. There is a need to clearly define the relationships of these nasal elements at the ossification level, during development.

METHODS

We investigated the three-dimensional construction of human foetal NC elements, including ST, MT, IT and vomer, using CBCT images from 16 weeks gestation (E16) to E31 (25 foetuses) and compared it to histochemical observations (E25).

RESULTS

At the stage of ossification, the studied elements are elongated in the posterior region near the sphenoidal bone, showing that the locations of the ST, MT, and IT are important during formation of the NC. CBCT analysis revealed that the horizontal and vertical directions of nasal turbinates affect the formation of the human NC.

CONCLUSION

The location and elongated development of the MT is one of the most important elements for NC formation. The relationship between the nasal sinus and nasal turbine at the level of ossification may provide useful information in clinical treatment of children.

Chronic nasal dysfunction

Chronic nasal dysfunction is a clinical concept in the diagnostic and therapeutic management of sinonasal diseases, based on the evo-devo theory of formation of the nose according to which the nose is not a single organ but rather an association of three organs: olfactory nose, respiratory nose and paranasal sinuses. In chronic nasal dysfunction theory, etiological diagnosis takes account of the possible pathophysiological independence of nasal symptoms, in accordance with the different origins and physiology of the three organs constituting the nose. The diagnostic approach of the chronic nasal dysfunction concept breaks down the pathology so as to propose treatment(s) adapted to the diseased organ(s) and to the capacity for physiological resolution of dysfunction induced in one organ by pathology in a neighboring nasal organ. The ethmoid is not a sinus according to evo-devo, and therefore functional endoscopic endonasal surgery (FEES) cannot be restricted to functional endoscopic sinus surgery (FESS). Evo-devo theory and the chronic nasal dysfunction concept offer an alternative to the concept of chronic rhinosinusitis with or without polyps for the management of sinonasal diseases.