DescriptionAn in-depth report on the causes, diagnosis, treatment, and prevention of sinusitis.
Alternative NamesAntibiotics; Decongestants; Nasal Congestion
Bacteria are the most common direct cause of acute sinusitis. (Other organisms might be the infecting agents in less common cases.) The ability of bacteria or other agents to infect the sinuses, however, must first be set up by conditions that create a favorable environment in the sinus cavities. Sinusitis is most often an acute condition, which is self-limiting and treatable. In some cases, however, the inflammation in the sinuses persists or is chronic do begin with. The causes for such chronic sinusitis cases are sometimes unclear.
Conditions that Predispose the Sinus Passages to Acute Bacterial Infection
The typical process leading to acute sinusitis starts with a flu or cold virus. Viruses themselves do not usually cause sinusitis directly. Instead, they set the stage by causing inflammation and congestion in the nasal passages (called rhinitis) that leads to obstruction in the sinuses. This creates a hospitable environment for bacterial growth, which is the direct cause of sinus infection. In fact, rhinitis is the precursor to sinusitis in so many cases that expert groups now refer to most cases of sinusitis as rhinosinusitis.
Rhinosinusitis tends to involve the following sinuses:
Nearly everyone with colds has inflamed sinuses. These inflammations are typically brief and mild, however, and most people with colds do NOT develop true sinusitis.
Conditions Leading to Chronic or Recurrent Sinusitis
Chronic or recurrent acute sinusitis typically results from one of the following conditions:
Chronic or recurrent acute sinusitis can be a lifelong condition.
The Role of Bacteria. The role of bacteria or other infectious agents is complicated in chronic sinusitis. They may play a direct, an indirect, or, in some patients, infectious agents may not play any role at all. For example, one study reported the following for patients with chronic sinusitis who had not responded to antibiotics:
Inflammatory Response, Allergies, and Asthma. The absence of bacterial agents as a causal factor in many cases suggests that some instances of chronic sinusitis may be due to a continuing inflammatory condition. Such on-going inflammation may have been triggered immune factors that were produced in response to injuries from acute sinusitis. Many of the immune factors observed in people with chronic sinusitis resemble those that appear in allergic rhinitis, suggesting that sinusitis in some individuals is due to an allergic response.
Allergies, asthma, and sinusitis often overlap. Those with allergic rhinitis (so-called hay fever and rose fever) often have symptoms of sinusitis, and true sinusitis can develop as a result of the mucus blockage it causes. A causal association, however, has not been proved, and many experts believe allergies themselves rarely predispose to sinusitis
Severe asthma (which is often associated with allergies) and chronic sinusitis often overlap, although the relationship is unclear. Between 53% and 75% of children with asthma caused by allergies have sinus abnormalities, and various studies have shown that between 17% and 30% of asthmatic patients develop true sinusitis. In fact, chronic sinusitis may actually be the cause of asthma in some cases.
Abnormalities of the Nasal Passage. Abnormalities in the nasal passage can cause blockage and thereby increase the risk for chronic sinusitis. Some include the following:
Infectious Agents that Cause Sinusitis
Bacterial Sinusitis. Bacteria are the most common infectious agents in sinusitis. The bacteria most commonly implicated in sinusitis are the following:
Other possible bacterial culprits include:
Fungal Sinusitis. While fungi are an uncommon cause of sinusitis, the incidence of such infections is increasing. An estimated 5-10% of chronic rhinosinusitis patients actually have a form of allergic fungal sinusitis. Considerable research is underway to understand the role fungi plays in the development of chronic sinusitis. Medical debate continues over the specific criteria for diagnosis and the best methods for treatment. Recent evidence supports early theories that fungal sinusitis is an immune, rather than infectious, disease. Fungi involved in sinusitis are the following:
There are four categories of fungal sinusitis:
Fungal infections can be very serious, and both chronic and acute fungal sinusitis require immediate treatment. Fungal ball is not invasive and is nearly always treatable.
Fungal infections should be suspected in people with sinusitis who also have diabetes, leukemia, AIDS, or other conditions that impair the immune system. Fungal infections can also occur in patients with healthy immune systems but they are far less common.
Viral Sinusitis. Viruses are directly implicated in only about 10% of sinusitis cases.
Infectious Agents in Chronic Sinusitis. The same organisms that cause acute sinusitis are often present in chronic sinusitis, but other agents are often detected in chronic cases that are not present in the original acute condition:
Sometimes bacteria or other organisms do not appear to be directly involved with chronic sinusitis.