Acute sinusitis: causes and pathogenesis
Last reviewed: 23.04.2024
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Causes of Acute Sinusitis
The development of inflammation of the mucous membrane of the paranasal sinuses is facilitated by conditions of both general and local nature. The general state of individual reactivity, constitutional prerequisites, immune forces of the body, as well as various adverse environmental factors. Among the local factors most often inflammation in the sinuses is promoted by those in which the drainage function of the discharge holes is disturbed, sinusal ventilation and the work of the mucociliary transport system.
Causes of impaired function of the outlets of the paranasal sinuses can be systemic (for example, allergies) and local (eg, hypertrophy of nasal conchae). Local, in turn, are divided into anatomical and pathophysiological. The first include the curvature, spines and crests of the nasal septum, hypertrophy of nasal concha, hyperplasia of the mucosa or polyps, various tumors. It is established that these factors not only disrupt the drainage and ventilation functions of natural anastomosis, but also in the long-term existence, especially in childhood, contribute to the incorrect development of the sinuses themselves (shape, size, diameter of the sastia and their course).
In the etiology of both acute and chronic sinusitis, infection, penetrating into the sinuses from the nasal cavity, teeth due to a nose injury or with a blood stream from a remote hearth is of primary importance. In the sinuses, cocco flora (streptococcus, staphylococcus, pneumococcus) is more often found, less often gram-negative and gram-positive rods, influenza viruses, parainfluenza, adenoviruses, fungal flora. Often, anaerobic bacteria are sown. Acute sinusitis is more often characterized by the presence of only one pathogen, chronic - a polymicrobial flora.
The pathogenesis of acute sinusitis
Pathophysiological factors contributing to the progression of the inflammatory process in the paranasal sinuses include: a dysfunction of the glands of the nasal mucosa, leading to excessive accumulation or lack of secretion, a change in the direction of the jet of inhaled and exhaled air in the nasal cavity, leading to disruption of gas exchange in the paranasal sinuses, inhibition of functions ciliary epithelium of the mucosa.
Difficult or, conversely, more free than normal, the passage of air through the nasal cavity leads to a change in ventilation in the sinuses. In turn, the violation of ventilation of the paranasal sinuses and air pressure in them lead to edematous inflammatory changes in the mucous membrane, which further disturbs the air exchange and drainage of the sinuses. Such changes, naturally, can become a favorable background for the development of various forms of sinusitis.
In the paranasal sinuses, due to the closure of natural anastomias, there is a stagnation of the secretion of the mucous glands, a change in pH, a metabolic disorder in the mucous membrane, a disruption of the function of the ciliated epithelium, and the activation of the opportunistic microflora.
Equally important in the development of pathological conditions of the nasal cavity and paranasal sinuses is the function of ciliated epithelium. Due to the strict rhythm of movements of the cilia of ciliated cells, secretion of the mucous membrane and various foreign particles from the nasal cavity and paranasal sinuses are transported towards the nasopharynx. The impact of a variety of factors, for example, mechanical, physical, chemical, biological, disrupts the function of the ciliated epithelium, and the cilia themselves are destroyed.
With acute inflammation, exudative processes predominate. In the early stages of exudate serous, then mucoid-serous, and with the attachment of a bacterial infection becomes purulent, with a large number of leukocytes and detritus. The blood vessels are dilated, the permeability of the capillaries rises and the edema of the mucous membrane develops.
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