Physicians make a diagnosis of chronic cough when a cough persists for eight weeks or longer in an adult or for four weeks or longer in a child.
In the vast majority of cases the cause of the cough is identified. In fact, the three most common conditions associated with a chronic cough, in more than 80 percent of cases, are:
Post nasal drip with secretions in the nose that drip down the back of the throat
Gastric acid esophageal reflux: Acid can flow backward into the esophagus (which is not prepared to handle the irritation of acid). The esophagus is innervated by the vagus nerve (it extends into the lung). The irritation (of the nerve) frequently results in respiratory symptoms including cough.
In some other cases of cough, the cause will be identified by other diagnostics such as x-ray which may identify bronchitis or pneumonia, or blood tests, which can identify an infection or a cancerous tumor in the upper respiratory tract, all of which can present with persistent cough.
But what about a persistent cough that does not seem to have an obvious cause? This situation can be quite distressing for the sufferer and also for those around him. This “condition” was recognized and named by the American College of Chest Physicians as a psychogenic cough in a 2006 position statement. The guidelines for management were revised recently in the March 2017 issue of Chest and the condition was renamed somatic cough. The term refers to a habitual cough that does not appear to be instigated or due to any of the conditions mentioned above.
The new revision of the guidelines suggests that the term “psychogenic cough,” used in the past, should now be dropped. The main reason is that psychologists were not comfortable with making the distinction between a cough due to psychogenic cause and a persistent cough instigated by psychological symptoms.
When someone has symptoms without explanation, it’s called somatization. This is different from another type of situation called malingering, when there is a conscious effort to demonstrate disease that does not exist. In somatization, the physical feeling (complaint) is real, but the cause is a transfer of psychological distress into a physical symptom.
In the past it was suggested that this persistent cough, similar to diarrhea associated with irritable bowel syndrome (IBS), occurs more often in the daytime. If the symptom (cough) awakened someone from sleep, then it would suggest an actual organic cause (and require serious investigation). This is no longer a criterion, according to the newly revised guidelines. Somatic cough can occur at night, as well, and can awaken someone from sleep.
Some suggested diagnostic criteria for cough somatization include:
Signs are present that indicate that the symptoms are distressing and resulting in significant disruption of (quality of) life. Thus, the association with psychologic disorders.
There are excessive thoughts, feelings or behaviors related to the cough rising from concern about the seriousness of one’s health.
Frequently there is resistance to treatment, which raises the consideration that the cough “serves a purpose.”
The cough reflex results from the stimulation of receptors in the airways known as “irritant receptors.” The stimulation can result from solid particles, secretions, different air temperature, or simply from the presence of excess fluid, as in the case of congestive heart failure (CHF). In somatic cough, there is the persistent feeling that “something in the throat area needs to come out,” even when there is nothing really there. It is that very persistent feeling that is the root of the (somatic cough) problem.
Not surprisingly, non-pharmacologic therapy is the most promising solution, although it also tends to be time-consuming and difficult to deliver without appropriately trained professionals. The list of non-pharmacologic therapies can include hypnosis; suggestion therapy; and reassurance and counseling.
Behavioral treatments where patients are taught to identify precipitating sensations to the cough are designed to help the patient believe that he is in control of the cough, rather than the other way around.
Real-time functional MRIs have identified activity in a specific part of the brain during the cough that would suggest that there is a voluntary component to the cough, rather than it being a reflex or a response. Based on those findings, patients can be taught to exert voluntary control to suppress the behavior.
The diagnosis of somatic cough is considered only after all possible causes have been ruled out. In addition to the previously mentioned considerations, an Ear Nose and Throat (ENT) specialist should look into the upper airways with a scope, with visualization of the vocal cords. Using the laryngoscope scope is crucial because unusual causes of a persistent cough, such as polyps and vocal cord movement dysfunction, can be missed when the scope is not used. The scope can also help make the more common diagnosis of erosions of the vocal cord due to acid reflux.
You can reference a previous column, “Speech Therapy Might Help With Chronic Cough,” which discussed speech therapy exercises for vocal cord disorders. In many cases, the persistent act of clearing the throat has the same mechanism as somatic cough.
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Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music. Find him on Twitter @Lung_doctor.