Sinusitis, a common nasal disease, causes numerous discomforts, such as nasal congestion, purulent nasal discharge, headache, and decreased sense of smell, significantly impacting quality of life. Understanding the causes of sinusitis is crucial for prevention and treatment.
Infectious Factors
Viral Infection: The common cold is one of the most frequent illnesses, and most colds are caused by viral infections, such as rhinovirus and coronavirus. When viruses invade the nasal cavity and sinus mucosa, they trigger an inflammatory response, leading to swelling, increased secretions, and blockage of the sinus openings. This prevents normal airflow within the sinuses and hinders the drainage of secretions, creating conditions conducive to bacterial growth and thus increasing the risk of sinusitis. This is especially true when the body's resistance is lowered, such as during periods of excessive fatigue, lack of sleep, or exposure to cold, making one more susceptible to viral infections and the development of sinusitis.
Bacterial Infection: Based on viral infection, the environment within the sinuses changes, creating a favorable environment for bacterial growth and reproduction. Common bacteria include Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. These bacteria further infect the sinus mucosa, exacerbating the inflammatory response and leading to sinusitis. In addition, infections of adjacent organs, such as odontogenic infections, can also cause sinusitis. For example, the roots of the maxillary second premolars and the first and second molars are located on the floor of the maxillary sinus. When these teeth become infected, the inflammation can spread to the maxillary sinus, triggering sinusitis.
Anatomical Abnormalities
Deviated Nasal Septum: The nasal septum is the central dividing structure of the nasal cavity and should normally be centered. However, some people have a deviated nasal septum, meaning the nasal septum bends to one or both sides, or has a local protrusion. This anatomical abnormality can obstruct nasal ventilation and drainage, preventing the smooth drainage of secretions from the sinuses. This accumulation of secretions within the sinuses can cause inflammation, leading to sinusitis.
Nasal Polyps: Nasal polyps are benign proliferative tissues of the nasal cavity and sinus mucosa, usually appearing as translucent, lychee-like growths. Nasal polyps can block the sinus openings, affecting sinus ventilation and drainage, leading to increased pressure within the sinuses, impaired blood circulation in the mucous membranes, and ultimately, sinusitis. The larger the nasal polyp, the more severe the impact on sinus ventilation and drainage, and the higher the risk of sinusitis.
Uncus hypertrophy and ethmoid bulla overdevelopment: The uncinate process and ethmoid bulla are part of the anatomical structure of the nasal cavity and sinuses. If the uncinate process is hypertrophied or the ethmoid bulla is overdeveloped, it will alter the normal airflow dynamics of the nasal cavity and sinuses, affecting sinus ventilation and drainage, causing secretions to accumulate in the sinuses, making them prone to bacterial growth, and inducing sinusitis.
Allergic Factors
Allergic Rhinitis: Allergic rhinitis is an allergic reaction of the nasal mucosa caused by allergens. Common allergens include pollen, dust mites, animal dander, and mold. When people with allergies come into contact with these allergens, the nasal mucosa will react allergically, resulting in symptoms such as sneezing, runny nose, and nasal congestion. Long-term allergic rhinitis can cause persistent swelling of the nasal mucosa, obstructing the sinus openings and affecting sinus ventilation and drainage, thus increasing the likelihood of sinusitis attacks.
Asthma: There is a close link between asthma and sinusitis. Asthma patients often experience inflammation of the nasal cavity and sinuses because their airways are highly reactive, making the nasal and sinus mucosa easily irritated and inflammatory. Furthermore, inflammatory mediators and secretions produced during sinusitis attacks can worsen asthma symptoms, creating a vicious cycle.
Environmental Factors
Air Pollution: Long-term exposure to heavily polluted environments, such as industrial exhaust, vehicle fumes, and dust, can irritate the nasal and sinus mucosa, damaging the ciliary movement function of the mucosa and reducing its clearance capacity. This makes it difficult to expel inhaled dust, bacteria, and other foreign objects in a timely manner, easily leading to inflammation of the sinus mucosa and triggering sinusitis.
Climate Change: Sudden climate changes, such as the stimulation of cold air or dry weather, can affect the normal function of the nasal and sinus mucosa. Cold air causes vasoconstriction in the nasal mucosa, impairing local blood circulation and reducing the mucosa's resistance, making it more susceptible to pathogen invasion. Dry weather causes the nasal mucosa to dry out and crack, increasing the chance of infection and thus inducing sinusitis.
Other Factors
Weakened Immunity: When the body's immunity is low, such as in cases of diabetes, HIV/AIDS, or long-term use of immunosuppressants, the body's defense mechanisms are weakened, making it unable to effectively resist the invasion of pathogens. The nasal and sinus mucosa are more susceptible to infection by bacteria, viruses, and other pathogens, thus triggering sinusitis.
Unhealthy Lifestyle Habits: Some unhealthy lifestyle habits, such as excessive fatigue, prolonged sleep deprivation, smoking, and excessive alcohol consumption, can affect the body's normal metabolism and immune function, reducing the body's resistance and increasing the risk of sinusitis attacks. For example, smoking irritates the nasal and sinus mucosa, damages the cilia movement of the mucosa, and affects sinus ventilation and drainage.
Sinusitis is the result of multiple factors working together. Understanding these causes allows us to take preventative measures in our daily lives, such as strengthening our constitution, avoiding allergens, keeping our nasal passages clean, and improving our living environment, to reduce the likelihood of sinusitis attacks and maintain the health of our nasal cavity and sinuses.
