"This study suggests that sinusitis is more common than we had previously thought in people with chronic cough," says Kaiser Lim, M.D., lead researcher and Mayo Clinic pulmonologist and allergist. "It also confirms our impression in the chronic cough clinic that many of our patients have underlying sinus inflammation as a cause of their coughs. Our findings in this series of patients place sinusitis among the top three reasons for chronic cough, along with acid reflux and rhinitis, inflammation of the nasal passages."
Chronic cough is defined as a cough lasting over three weeks. According to Dr. Lim, an estimated 23 million Americans see their physicians each year for cough. How many have been coughing for more than 21 days is yet unconfirmed.
Dr. Lim and colleagues conducted this study as a retrospective review of data from 672 chronic cough patients seen at Mayo Clinic over one year. Physicians had obtained CT scans for 132 of these patients suspected of having sinusitis, with significantly abnormal results indicating sinusitis in 49 patients, or 37.1 percent. The more severe the sinus abnormalities found in the CT scans, the more likely the patients were to be ultimately diagnosed with sinusitis as the cause of chronic cough. Physical examination of the nose and mouth did not predict significant sinus abnormalities shown in the CT scans.
The chronic cough patients Dr. Lim studied had been coughing for an average of 52 months. "The diagnosis had not been made for over four years -- and the shame of it is that many of the people had been coughing due to something you could potentially treat," says Dr. Lim.
Dr. Lim explains that sinusitis is often overlooked by physicians as a culprit in chronic cough. In addition, many patients in Dr. Lim's study had been told by their physicians to learn to live with their coughs.
"It's also not unusual for chronic coughers to simply give up on getting a diagnosis and treatment for the underlying problem and resign themselves to live with the coughing," says Dr. Lim. "Thus, you find situations like women who have to wear sanitary pads for urinary leakage due to their coughing and men who can't have hernia surgery because of their constant coughs."
To determine whether sinusitis might be the underlying cause of a patient's chronic cough, a patient should undergo a complete ear, nose and throat evaluation including rhinoscopy -- a nasal passage exam using a tiny flexible fiberoptic scope -- and/or a CT scan of the sinuses, according to Dr. Lim. "It is hard to make a diagnosis of sinusitis without looking into the nose or with a CT scan of the sinuses," says Dr. Lim. "Symptoms alone do not predict whether you have sinusitis."
Sinusitis can manifest as weeping mucus that drips down the throat, which can cause irritation and prompt coughing. Sinusitis is not only tricky to diagnose but also can be difficult to treat, according to Dr. Lim. Appropriate treatment includes the use of prednisone, antifungal sprays or sinus surgery, depending on the severity of the sinus inflammation. Sinusitis also tends to recur.
Previously, physicians have often lumped sinusitis and its symptoms together with postnasal drip syndrome from rhinitis as a potential cause of chronic cough, says Dr. Lim. "But this is a problem, as the treatment for rhinitis is not the same as for sinusitis," he says. "Medications designed for rhinitis do not penetrate into the sinuses very well."
It's often difficult to assign a specific cause to chronic cough, according to Dr. Lim. "It's not uncommon for several illnesses to occur at the same time in the same patient," he says. "That's why even when an abnormality has been diagnosed, it has to be treated specifically. Only once this abnormality has resolved and in parallel the cough resolves, can you say whether or not the condition diagnosed is causing the cough."
Dr. Lim advocates intensive treatment for sinusitis in chronic coughers. "If the cough doesn't go away, it's probably the wrong diagnosis or it has not been treated adequately," he says. "If diagnosed correctly and then treated aggressively, it will go away. You can always repeat the CT scan of the sinuses to document whether or not the treatment is effective in controlling the sinuses."
Researchers do not know why chronic coughers who have sinusitis developed the sinus inflammation.