Paranasal sinus hypoplasia is a clinical manifestation of craniosynostosis. Paranasal sinuses, also known as paranasal sinuses or sinuses, are air-containing cavities within the cranial bones (frontal, pterygoid, maxillary, sieve) surrounding the nasal cavity, all of which have sinus openings to the nasal cavity. They play a resonant role in articulation. Sinuses left and right pairs, a total of four pairs, respectively, called frontal sinus, maxillary sinus, butterfly sinus and sieve sinus. 1, frontal sinus (frontal sinus): located in the frontal bone bone arch deep, opening in the middle nasal tract sieve funnel. 2, maxillary sinus: located in the maxilla body, opening in the middle nasal tract at the half-moon fissure. 3.Pterygoid sinus (sphenoid sinus): located in the body of the pterygoid bone, opening in the septal fossa of the pterygoid sieve. 4.Septal sinus (ethmoid sinus): located in the upper septal labyrinth, and divided into anterior, middle and posterior septal sinus. The anterior and middle sieve sinuses open in the middle nasal tract, and the posterior sieve sinus opens in the upper nasal tract. The paranasal sinuses are lined with mucous membranes that continue with the nasal mucosa, all of which are ciliated columnar respiratory epithelium containing cupped cells and glands. The movement of the mucosal cilia of the sinuses is directed toward the natural sinus opening, facilitating the discharge of secretions from the sinuses. Inflammation of the nasal mucosa can often spread to the paranasal sinuses causing sinusitis. If the inflammation spreads to the maxillary sinus, due to the large volume of the maxillary sinus, the opening position is high and small, the natural drainage is not smooth, easy to become chronic inflammation, and does not heal. The role of the paranasal sinuses is to play a resonant role mainly for articulation. In addition, the paranasal sinuses are rich in blood vessels, which can help regulate the temperature and humidity of the inhaled air.