What causes sinusitis?

Clinical anatomy and physiology of the paranasal sinuses

There are four pairs of paranasal sinuses: frontal, maxillary, ethmoid and sphenoid. The frontal sinus resembles a pyramid, its base is the floor of the sinus. The maxillary sinus borders medially on the lateral wall of the nose, above on the lower wall of the orbit, in front on the canine fossa, below on the alveolar process of the maxilla. The cells of the ethmoid labyrinth are limited above by the base of the skull, laterally by a very thin bone plate that serves as the medial wall of the orbit. The sphenoid (main) sinus borders on vital structures: the pituitary gland, carotid artery, ophthalmic nerve and cavernous sinus.

The paranasal sinuses communicate with the nasal cavity through narrow openings. The frontal and maxillary sinuses, as well as the anterior cells of the ethmoid labyrinth, open into the anterior part of the middle nasal passage, the sphenoid sinus and the posterior cells of the ethmoid labyrinth - into the superior nasal passage. Natural drainage occurs through these openings; edema, infiltration of their mucous membrane lead to congestion in the sinuses, and therefore, to the possibility of sinusitis.

At birth, a child already has a maxillary sinus and several cells of the ethmoid labyrinth. The maxillary sinus is located above the bottom of the nasal cavity until approximately three years of age, then gradually descends, and in an adult, the bottom of the sinus can be 0.5-1.0 cm below the bottom of the nasal cavity. It is very important to know about the relationship between teeth and the maxillary sinus. In early childhood, the closest tooth to the maxillary sinus is the canine, from approximately 5-6 years of age, the sinus is closely associated with two premolars and molars. The ethmoid sinus is finally formed by the age of 7-8 years.

The frontal sinus is absent in a newborn, it begins to develop already from the first year of life, completing its formation by the age of 25. It is important to know that the posterior wall of the frontal sinus borders the anterior cranial fossa, due to which intracranial sinusogenic complications may develop: meningitis, brain abscess, etc. The sphenoid sinus in newborns looks like a gap, and its formation, beginning at the age of 4-5 years, ends by the age of 20. However, at 12-14 years it is already well expressed.

What are the paranasal sinuses for?

This question still remains without a definitive answer, although there are quite a few theories on this matter. For example, it is believed that they serve as sound resonators, reduce the mass of the skull, increase the surface of the olfactory region, soften blows to the face, improve the humidification and warming of inhaled air, regulate intracavitary pressure, etc.

Recently (especially in connection with the development of modern endoscopic surgery), much attention has been paid to the study of mucus transport from the sinuses through natural openings, the so-called clearance. The paranasal sinuses are lined with ciliated cylindrical epithelial cells, goblet and mucous glands that produce secretion. For normal evacuation of this secretion, the mechanism of its transport must function well. However, this mechanism is often disrupted by air pollution, its increased dryness, disorders of parasympathetic innervation, not to mention the toxic effects of microorganisms.

Acute respiratory and infectious diseases are of particular importance in the development of acute sinusitis in children. At the same time, there are factors that contribute to the development of sinusitis. These include chronic hypertrophic rhinitis, curvature of the nasal septum, spines, nasal polyposis and especially adenoid vegetations. Acute sinusitis is much more often detected in children with allergic rhinitis, as well as with a reduced level of immunity, often suffering from acute respiratory infections. Acute inflammation of the maxillary sinus can be of odontogenic origin, associated with a fungal infection, trauma, etc.

Recently, in connection with the development of modern endoscopic surgery, much attention has been paid to the study of mucus transport from the paranasal sinuses through natural anastomoses, the so-called mucociliary clearance. The paranasal sinuses, like the nasal cavity, are lined with ciliated epithelium, and glands and the secretion they produce also participate in its normal functioning. With air pollution, its increased dryness, disorders of parasympathetic innervation, as well as under the influence of toxins of pathogenic microorganisms, the normal functioning of mucociliary clearance is disrupted, which leads to the development of sinusitis.

It is especially necessary to dwell on such a serious disease as osteomyelitis of the upper jaw. It develops in newborns, often the infection is transmitted through contact with an infected mother's nipple, dirty toys. Gingivitis occurs successively, then the tooth germ and the maxillary bone are involved in the process. Sequesters and fistulas are formed in the alveolar process. One-sided infiltration of the face quickly develops, closing the eye, swelling of the lower eyelid, chemosis. The disease is differentiated from dacryocystitis, erysipelas, endophthalmitis. The danger of osteomyelitis of the upper jaw is the possibility of developing septicemia. Treatment is complex, broad-spectrum antibiotics are used, good drainage is provided surgically, but in this case it is important not to damage the tooth germs.

Pathogenesis of sinusitis

In acute catarrhal inflammation, the mucous membrane thickens tens of times, up to filling the entire lumen of the sinus. Serous impregnation and sharp edema of the mucous membrane, cellular infiltration, dilated vessels, accumulation of exudate with the formation of extravasates are characteristic. Acute purulent inflammation is characterized by purulent deposits on the surface of the mucous membrane, hemorrhages, hemorrhages (in flu), pronounced round-cell infiltration. Periostitis and osteomyelitis processes are possible, up to sequestration.