The management of chronic cough, a common complaint in children, is challenging for most health care professionals. Millions of dollars are spent every year on unnecessary testing and treatment. A rational approach based on a detailed interview and a thorough physical examination guides further intervention and management. Inexpensive and simple homemade syrups based on dark honey have proved to be an effective measure when dealing with cough in children.
Key points
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Cough not associated with “colds” may be present in up to 28% of boys and 30% of girls.
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Chronic cough in children lasts more than 4 weeks. In 3 to 4 weeks most infectious causes of cough should have resolved.
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Cough can be classified as specific or nonspecific. Specific cough has clinical characteristics or “pointers.” The characteristics of the cough point to a possible cause.
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Most common causes behind chronic cough include recurrent respiratory tract infections, postinfectious cough, protracted bacterial bronchitis, gastroesophageal reflux, laryngopharyngeal reflux, asthma and upper airway cough syndrome.
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Over-the-counter cough medicines are not recommended by the American Academy of Pediatrics (AAP). The Food and Drug Administration (2008) did not approve its usage for children younger than 4 years. Codeine and dextromethorphan are efficacious in reducing severity and frequency of chronic cough in adults.
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The AAP recommends treating cough in children with homemade syrup based on buckwheat honey (a dark variety of honey).
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Novel therapies for symptomatic treatment currently being studied are targeting specific channels and receptors involved in the cough reflex pathway (eg, transient receptor potential [TRP] channels).
Introduction
In the United States cough is the most common complaint for medical office visits, accounting for 3% of medical consultations during childhood. Recent community-based surveys have shown that cough not associated with “colds” may be present in up to 28% of boys and 30% of girls.
Certainly, cough in children is disruptive not only for the child but also for the parents. It impairs the quality of life in both, adding significant stress. It affects the child’s sleep, school performance, and playtime. It creates anxiety for parents who fear that their child is ill, and annoys teachers and classmates in the school setting.
An efficient and rational approach to the management of the child with a cough invites the following considerations.
Introduction
In the United States cough is the most common complaint for medical office visits, accounting for 3% of medical consultations during childhood. Recent community-based surveys have shown that cough not associated with “colds” may be present in up to 28% of boys and 30% of girls.
Certainly, cough in children is disruptive not only for the child but also for the parents. It impairs the quality of life in both, adding significant stress. It affects the child’s sleep, school performance, and playtime. It creates anxiety for parents who fear that their child is ill, and annoys teachers and classmates in the school setting.
An efficient and rational approach to the management of the child with a cough invites the following considerations.
Defining cough
Cough is a protective reflex. It is part of the normal respiratory physiology of the mucociliary system responsible for clearing excessive secretions and airway debris from the respiratory tract. Cough is the key component for the airway’s defense mechanism. From the larynx to the segmental bronchi, there are receptors capable of triggering cough. These receptors are stimulated by chemical irritants and mechanical stimuli. The physiology of the cough reflex involves a central and a peripheral pathway. The central pathway is a brainstem reflex associated with the center controlling the breathing function. This center undergoes a differentiation process in children reaching maturation by adolescence. In comparison with adults, children’s neurologic characteristics associated with the cough reflex are more sensitive to certain environmental exposures.
Normal or expected cough in children
Healthy school-age children with no respiratory illness may experience approximately 11 cough episodes per day with no other symptoms associated. According to Munyard and Bush, previously healthy children may cough 34 times in a 24-hour period. These “normal” coughing episodes may be worrisome for parents and may be mistaken for other disorders.
When cough becomes abnormal: chronic cough
Chronic cough in children has been defined as a daily cough that lasts more than 4 weeks. There is no clear definition on when cough should be considered acute or chronic among the pediatric population. A period of 1 to 3 weeks allows most infectious causes of cough to have resolved in children. Based on the features associated with cough, for practical reasons it can be classified as specific or nonspecific. Specific cough is when there are clinical characteristics or “pointers” associated with the cough ( Table 1 ). Unlike in the adult population, these characteristics are more recognizable in children and point to a possible origin: brassy, croupy, honking, staccato. These pointers permit the early recognition of the cause (eg, the brassy cough associated with tracheomalacia has a sensitivity of 57% and specificity of 81%). Nonspecific cough is a dry chronic cough in an otherwise healthy child, which has no other clinical symptoms associated with it. It has been postulated that the majority of children with a nonspecific cough show an association with increased cough receptor sensitivity and postinfectious cough. Some studies suggest that it may resolve spontaneously.
| Cough Characteristic | Suggested Underlying Etiology |
|---|---|
| Wheezing episodes, other atopy (eg, eczema), dry cough worse at nighttime | Asthma, gastroesophageal reflux disease |
| Clearing throat, allergic salute | Upper airway cough syndrome |
| Wet or productive cough | Cystic fibrosis, protracted bacterial bronchitis, primary ciliary dyskinesia, immune deficiency |
| Choking with feeds | Recurrent aspiration |
| Brassy or barking cough, stridor | Croup, tracheomalacia/bronchomalacia, airway compression |
| Honking cough, absent during sleep | Psychogenic cough |
| Progressive with weight loss, fevers | Tuberculosis |
| Staccato | Chlamydia |
| Paroxysmal (with or without whoop) | Pertussis and parapertussis |
| Dry cough and restrictive spirometry | Interstitial lung disease |
Most common causes of chronic cough
Recurrent Respiratory Tract Infections
Recurrent episodes of respiratory infections are the main cause of chronic cough in healthy children, especially among those of preschool age. Parents may appreciate it as a single prolonged episode of upper respiratory infection (URI) associated with cough for several weeks. In reality, after further questioning there is a recognizable period (sometimes very short) of improvement. Moreover, if a child has not fully recovered from a previous upper respiratory infection and acquires a different virus causing similar symptoms, the cough associated with it may seem prolonged. URIs are episodic, increase in frequency during winter, and are associated with crowded living conditions, exposure to environmental pollution, and attendance at daycare facilities. Monto identified a mean annual incidence for URIs in children younger than 4 years of 5 to 8 episodes, and in children between 10 and 14 years of 2.4 to 5 episodes.
In a 2-year prospective cohort study done in 2003 in the Netherlands by Versteegh and colleagues, the frequency of different respiratory pathogens in children with prolonged coughing was investigated. A single infectious agent was found in 36%, 2 in 26%, and more than 2 in 5% of the children. Among the most frequent pathogens, they identified rhinovirus (32%), pertussis (17%), and respiratory syncytial virus (11%). A very strong seasonal influence on the number on infections, but not on the number of mixed infections, was recognized. The investigators also concluded that there was a high frequency of mixed-pathogen infections regardless of the season, with an increased frequency in older children.
Postinfectious Cough
Postinfectious Cough is a troublesome condition that affects the patient during the day and night, following a respiratory infection. It may last more than 3 weeks, but usually less than 8 weeks. It has been reported that up to 40% of school-age children continue coughing 10 days after a common cold, with 10% of preschool children having a persistent cough after 25 days.
Epithelial disruption and inflammation by neutrophils and lymphocytes are thought to play a main role in the etiology. Inflammation of the mucosa promotes the production of mucus, stimulating the cough receptors and the expectoration or clearance of the airway. Of note, less than 5% of coughs persisting for more than 8 weeks are believed to be postinfectious (other than pertussis). Mycoplasma infection should also be considered when the cough presents in school-age children or adolescents.
Bordetella pertussis ( [CR] ) is a gram-negative bacterium that causes a unique respiratory infection associated with prolonged coughing after resolution of the disease. It is characterized by spasmodic episodes of cough after the initial infection, which resolves slowly over a period of up to 6 months. A prospective study of 64 school-age children with documented B pertussis infection, performed in 2006 by Harnden and colleagues, concluded that infected children may continue coughing as long as 2 months after the onset of their illness. Pertussis infection should be suspected in children with a known sick contact even if the child has been immunized, as partial vaccine failure has been reported.
Protracted Bacterial Bronchitis
This term was introduced by Marchant and colleagues and was defined as a chronic wet cough that lasts more than 4 weeks in the absence of underlying respiratory disorders (ie, cystic fibrosis, primary ciliary dyskinesia, immunodeficiencies), and achieves resolution with antibiotic therapy. It is poorly characterized and is misdiagnosed most of the time as asthma. This concept is not readily accepted by the pediatric population, and has been described as an adult illness. Nonetheless, it has been suggested that most children with chronic wet cough have a bacterial infection in the lower respiratory tract. The disease is caused by biofilms of bacteria in the airway associated with an intense neutrophilic airway inflammatory response. The most common organisms associated with protracted bacterial bronchitis are Streptococcus pneumoniae , Haemophilus influenzae , and Moraxella catarrhalis . If avoidance of a diagnostic bronchoscopy is desired, a reasonable approach is a trial with antibiotics.
A prospective study in children with a median age of 2.6 years indicated that the primary cause of cough was a protracted bacterial bronchitis in 40%. Upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD) accounted for less than 10% of cases. Similarly, in 2011 Zgherea and colleagues reviewed 197 charts of children (0–3 years of age) with wet cough, and concluded that 56% of cases had purulent findings on bronchoscopy and, subsequently, 46% had positive bacterial cultures. Among the most common bacteria identified were H influenzae (49%), S pneumoniae (20%), M catarrhalis (17%), Staphylococcus aureus (12%), and Klebsiella pneumoniae (in 1 patient). The diagnosis is made clinically, and investigation for underlying conditions (cystic fibrosis, immunodeficiencies) must be sought. Physiotherapy and a prolonged course of antibiotic treatment (4–6 weeks) are recommended.
Gastroesophageal Reflux and Laryngopharyngeal Reflux
Gastroesophageal/laryngopharyngeal reflux is a physiologic event that happens in healthy children, and is also present in 40% to 65% of healthy infants. It peaks at 1 to 4 months of age, resolving spontaneously by 12 months. It becomes a disease when it is accompanied by symptoms (apnea, bradycardia, arching back, cough, failure to thrive), mucosal damage, and physical complications. Dysfunction of the lower esophageal sphincter is the major cause, but impaired acid clearance may also play a role. The theory behind the association between GERD and cough is not clear, but one proposed hypothesis involves irritation of the vagal nerve fibers in the esophagus. This event results in parasympathetic response that produces bronchoconstriction, stimulating the cough. Another hypothesis proposes that acidification of the distal portion of the esophagus stimulates cough receptors present in the mucosa. For infants and children, a detailed history and physical examination should be sufficient to identify gastroesophageal reflux, and diagnostic testing is not usually necessary. Further evaluation is only indicated when complications resulting from the disease have been identified. Various diagnostic tests are available: barium contrast study (upper gastrointestinal series in fluoroscopic examination), esophageal pH monitoring, esophageal manometry, endoscopy with biopsy, and scintigraphy. Therapy includes lifestyle modifications including volume restriction for feeds, positioning, and adding materials to thicken the feeding, such as rice solids. Pharmacologic therapy includes antacid H2-blockers (eg, ranitidine) and proton-pump inhibitors (eg, omeprazole) for children older than 1 year.
Asthma
Asthma is a chronic airway inflammatory disease associated with bronchial hyperresponsiveness and reversible airway obstruction. It is characterized by cough, wheezing, shortness of breath, and chest tightness. The presence of other atopic features such as allergic rhinitis, eczema, allergic conjunctivitis, and urticaria are helpful in confirming atopy and supporting the diagnosis of asthma. Cough-variant asthma is a variation in which the sole manifestation is cough, with no associated wheezing. A heightened cough reflex sensitivity appears to be the cause in this case. Diagnosis is supported by a strong atopic history, rapid improvement with antiasthma medication, and relapse after such medication is stopped. Diagnosis can be further supported by allergic testing (eg, skin prick) and spirometry. Nocturnal cough has been used frequently as an indicator of asthma in children; nonetheless, Ninan and colleagues reported that only one-third of children who presented with cough during the night (with no associated wheezing or breathing difficulty) had any association with asthma. A cough that wakes up a child from sleep suggests 2 possibilities: underlying reactive airway disease or asthma, and GERD; the latter is exacerbated while the child is lying down.
Upper Airway Cough Syndrome
This new term has been preferred over the well-known postnasal drip syndrome when discussing cough associated with upper airway conditions. The specific abnormalities associated with this syndrome are allergic rhinitis, nonallergic rhinitis, nonallergic rhinitis with eosinophilia, postinfectious rhinitis, bacterial sinusitis, allergic fungal sinusitis, abnormal anatomy, chemical or irritant rhinitis, and rhinitis medicamentosa. Afferent fibers from the vagus nerve are embedded in the posterior pharynx. For this reason, any abnormality affecting this area will trigger cough including the nasal secretions. The latter has inflammatory capacity and direct mechanical stimulation of the cough receptors ; this is also apparent in children with the common cold who suffer postnasal drip and subsequent cough. Other irritants aside from mucus can trigger the receptors, including changes in temperature or humidity. Diagnosis relies on the history taking and physical examination. Most of the time imaging will be unnecessary. With regard to therapy, patients with postnasal drainage refractory to antihistamine medications may benefit from intranasal corticosteroid and/or anticholinergic nasal spray (ipratropium bromide). This agent may provide the drying effect required with minimal secondary reactions and may be used in children older than 5 years. Nasal steroids are indicated for children older than 2 years.
Other less common causes
Otogenic Causes: Stimulation of Arnold Nerve
In some cases the auricular branch of the vagus nerve can be stimulated by a foreign body in the ear canal, triggering cough. A similar response will be produced whenever the posterior-inferior wall of the external acoustic meatus is stimulated. There have been cases reported of chronic cough triggered by wax impaction and cholesteatoma. Despite the rarity of this diagnosis in actual practice, physicians should maintain awareness of its possibility when examining the patient.
Inhalation of Foreign Body
Inhalation of a foreign body may be considered at any age, but most commonly in children between 1 and 3 years old. Most of the time, coughing will occur acutely and needs to be addressed promptly (especially with vegetable matter: popcorn and peanuts). A history suggestive of foreign-body aspiration should trigger the appropriate consultation to consider endoscopy. In some cases, a previously missed inhalation of a foreign body can lead to chronic cough (nonvegetable small objects). A missed case can lead to permanent lung damage. Vegetable matter (eg, peanuts and popcorn) are associated not only with obstruction but also with erosion and scarring. Nonvegetable objects (eg, metal, plastic, or other biologically inert material) are not associated with an inflammatory response, and symptoms may be mild, potentially leading to a missed diagnosis.
Functional Respiratory Disorder
Functional respiratory disorder (FRD) has been variably referred to as habit cough, tic cough, and psychogenic cough. It is has been described as a tic-like cough, characterized by sudden, brief, intermittent, involuntary, or semivoluntary movements or sounds. Phonic tics include cough, throat clearing, sniffing, and grunting, occurring most commonly in older children and adolescents. Symptoms may be precipitated by a viral infection and are sometimes associated with secondary gain (school absence). The cough of FRD can be mistakenly attributed to asthma or UACS if the cough is dry. The usual presentation is a harsh, dry, honking, repetitive cough that occurs throughout the day. Affected children often remain unperturbed. The condition improves with activities that distract the child, resolves with sleep, and is often exacerbated by stress. Habit cough is a diagnosis of exclusion and usually responds to behavioral modification techniques rather than pharmacotherapy.
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