Congenital Malformations of the Nose and Paranasal Sinuses

Abstract

Congenital anomalies occur because of errors during embryogenesis. For this reason, in order to understand the malformations of the nose and sinuses, normal development of these structures should be known well. Depending on the affected period during development, various malformations, ranging from the absence of full development of sinonasal structures to a malformation with mild severity, may be observed. At the third to fourth weeks of fetal life, frontal process and one pair of maxillary and mandibular processes begin to appear. Maxillary and mandibular processes are separated from each other by stomodeum, which is the primitive mouth. Nasal placodes of ectodermal origin migrate caudally and form the lateral and medial nasal processes. At the following weeks, lateral and medial nasal processes unite to form the nasal cavity. Nasal cavity is separated from the oral cavity by bucconasal membrane. The fusion of medial nasal processes (MNP) is the precursor of philtrum, columella, upper lip, nasal bone, and cartilage. At the sixth week of intrauterine life, by the fusion of maxillary and medial nasal processes, palatal structure begins to develop. The frontal nasal process is the precursor of septum and is created in the ninth week by the persistence of neural crest cells. At the tenth week, palatal structures unite with an inferior septum. At 11th and 12th weeks, the developments of uvula and soft palate are completed. Bucconasal membrane which separates posterior nasal cavity from the oral cavity regresses in the fifth to sixth months of intrauterine life. With canalization of the nasal cavity, the epithelial plugs filling the cavity are resorbed within the following weeks. In this chapter, congenital malformations of the nose and paranasal sinuses are presented.