Nasal development occurs during weeks 4 through 10 of gestation. Migrating neural crest cells populate the frontonasal prominence, one of five facial prominences, and form the nasal or olfactory placodes. These placodes appear as convex thickenings on the surface ectoderm of the frontonasal prominence. A central depression deepens in the placodes to form the primitive nasal pit. Mesenchymal proliferation during the 5th week around the nasal placodes allows the horseshoe-shaped medial and lateral nasal prominences to develop and fuse to form the nostrils. The nasal pits grow toward the oral cavity and develop into the early nasal fossae. The nasobuccal membrane separates the nasal cavities from the oral cavity. This membrane subsequently disappears, allowing for communication of the nasal cavities with the oral cavity, forming the primitive posterior nasal choanae. The nasomedial process gives rise to part of the nasal septum and the medial crus of the lower lateral alar cartilage. The nasolateral process develops into the external wall of the nose, nasal bones, upper lateral cartilage, alae, and lateral crus of the lower lateral cartilage. The apex and dorsum of the nose develop from the frontonasal process (Figure 11–1).
Diagram of embryologic development of the nose.
The proposed classification of congenital nasal deformities separates them into four categories. Type I deformities represent hypoplasia and atrophy, Type II are hyperplasia and duplications, Type III are clefts, and Type IV deformities consist of neoplasms and vascular anomalies.
Neskey D, Eloy JA, Casiano RR. Nasal, septal, and turbinate anatomy and embryology. Otolaryngol Clin North Am
. (The article describes development and anatomy of nasal structures.)
Szeremeta W, Parikh TD, Widelitz JS. Congenital nasal malformations. Otolaryngol Clin North Am
. (The article discusses embryology and development of congenital nasal abnormalities.)
Losee JE, Kirschner RE, Whitaker LA et al. Congenital nasal anomalies: a classification scheme. Plast Reconstr Surg
. (The article proposes a classification of congenital nasal deformities.)
Arrhinia is a rare congenital absence of the nose. The findings include absence of nasal bones, cribriform plate, and nasal septum. In cases of total arrhinia, the olfactory system is also absent. Arrhinia can be associated with other craniofacial anomalies and midline defects.
The likely embryologic abnormality resulting in arrhinia is thought to be a failure of the nasal placodes to invaginate during the 5th week of fetal development. Most cases reported are sporadic, although cases of genetic aberration have been described.
A computed tomography (CT) or magnetic resonance imaging (MRI) scan is performed to plan for surgery and often reveals associated abnormalities. Radiological examination demonstrates small or absent nasal bones and bony masses obstructing the nasal cavity.
All cases require airway management ...