DEFINITION OF THE COMPLAINT
Cough is one of the most common presenting complaints to pediatricians. Importantly, a cough is not a disease by itself, but rather a manifestation of an underlying pathology. A cough is a protective action, and can be initiated both voluntarily and via stimulation of cough receptors located throughout the respiratory tract (ear, sinuses, upper and lower airway to the level of the terminal bronchioles, pleura, pericardium, and diaphragm). A cough may serve to remove irritating substances, excessive/abnormal secretions, or may be secondary to intrinsic/extrinsic airway compression.
A cough is divided into four distinct phases: inspiratory, compressive, expiratory, and relaxation. These phases are characterized by deep inspiration, closure of the glottis, contraction of expiratory muscles with glottic opening, and relaxation of intercostal and abdominal muscles. Thus, one can see how selective patients with laryngeal or neuromuscular diseases may have ineffective coughs.
Classification should initially involve differentiating an acute from a chronic cough. A chronic cough is one which lasts longer than 3 weeks. Furthermore, the clinical description of the cough can often be helpful in suggesting an etiology: staccato (pertussis, chlamydia), barking (croup), grunting (asthma), or honking (psychogenic). Timing of the cough, relationship to daily activities, and age of the patient are important factors in further defining the etiology (Table 4-1).
TABLE 4-1. History and physical examination for cough.
COMPLAINT BY CAUSE AND FREQUENCY
Overall, some of the most common causes of chronic cough include viral upper respiratory tract infections and asthma (Table 4-2). Beyond these etiologies, age is very important in creating a differential diagnosis for the patient with a chronic cough (Table 4-3). Causes of cough may also be divided by diagnostic category including infectious, allergic/inflammatory, congenital malformations, irritants, aspiration, psychogenic, and other categories (Table 4-4).
TABLE 4-2. Most common causes of cough in children.
Upper respiratory tract infections
Allergic rhinitis/postnasal drip
TABLE 4-3. Causes of cough in childhood by age.
TABLE 4-4. Cause of cough in childhood by etiology.
In most cases of a child who presents with a cough, the diagnosis is obtained with a thorough history and physical examination. The following questions may help to define the diagnosis:
• Did the cough begin with an upper respiratory tract infection?
—The most common cause for a cough is a viral upper respiratory tract infection. This can occur with or without reactive airways disease/asthma. Without other significant generalized signs of illness or respiratory distress, often no significant initial evaluation or therapy is necessary. Many young children will have frequent (6–8) viral infections per year accompanied by a cough, giving the appearance of chronic cough.
• Are there systemic signs or symptoms that may suggest a particular etiology?
—Fevers, sinus tenderness, and headaches can be present with sinusitis. Weight loss and night sweats may indicate tuberculosis or malignancy. Dysphagia suggests an esophageal foreign body, whereas dysphonia indicates laryngeal or glottic pathology.
• In young infants, is there any history of conjunctivitis in association with a cough and tachypnea?
—Conjunctivitis and pneumonitis in a young infant may suggest infection due to Chlamydia trachomatis.
• Are there environmental stimuli that may irritate the airway?
—Passive smoke in infants and young children and active smoking in adolescents can trigger a chronic cough. Solvent fumes as well as recreational drug use can exacerbate a chronic cough.
• How is the cough related to time of day and to daily activities?
—A cough which is most prominent during or after eating is suggestive of aspiration or gastroesophageal reflux. If exposure to cold air and exercise precipitates the cough, reactive airway disease should be considered. Seasonal coughing suggests an allergic component. Similarly, a nighttime cough may indicate postnasal drip secondary to either allergies or sinusitis.
• Does the cough resolve with sleep?
—Coughs which disappear when the patient is asleep or appear only when an adult is present may suggest a psychogenic cough.
• Is there a history of a choking episode?
—Often, a significant choking episode occurs at the time of foreign body ingestion. For this reason, a thorough history is essential. Foreign body aspiration is most common in toddlers; however, older siblings can often place inappropriate objects in the mouth of infants. If foreign body aspiration is suspected, one should obtain either lateral decubitus or inspiratory and expiratory chest roentgenograms.
• Is there a history of recurrent pneumonias or other infections?
—Recurrent infections should cause one to consider immune dysfunction such as HIV and congenital immunodeficiencies. Recurrent pneumonias associated with sinusitis, multiple otitis medias, bronchiectasis, and situs inversus, suggest primary ciliary dyskinesia.
• How is the patient’s growth?
—Failure to thrive, steatorrhea, and recurrent pneumonias can occur with cystic fibrosis. Other features suggestive of cystic fibrosis are nasal polyps, recurrent sinusitis, and rectal prolapse.
• Is there any history of hemoptysis?
—Hemoptysis can be seen with a viral or bacterial pneumonia. However, it is also present in many other conditions, including fungal disease, autoimmune diseases, granulomatous disorders, cystic fibrosis, congenital heart disease, tuberculosis, and pulmonary hemosiderosis.
GENERAL DIAGNOSTIC APPROACH
Commonly, cough is self-limited and rarely requires intervention. However, chronic cough (i.e., cough lasting longer than 3 weeks) suggests an underlying disease process requiring close investigation. A detailed history and physical examination will often lead to a diagnosis. However, adjunctive diagnostic tests, such as chest radiography and spirometry, may further aide this process. As discussed above, the patient’s history will elucidate important information, such as age, circumstances present at onset of cough, nature of the cough, timing, triggers, and response to previous therapies. Medical, family, and medication histories will also provide important information regarding associated signs and symptoms. Physical examination will further validate a suspected diagnosis. Specifically, examination should pay particular attention to the presence and absence of the following: failure to thrive, signs of increased work of breathing (tachypnea, retractions, accessory muscle use, chest wall appearance, and airway sounds), allergic signs (shiners, boggy nasal turbinates, nasal polyps, halitosis, and pharyngeal cobblestoning), abnormal heart sounds, hepato- and/or splenomegaly, digital clubbing, cyanosis, and hypotonia. Chest radiography rarely provides a definitive diagnosis (except possibly in the case of foreign body aspiration) but will provide important information if subsequent diagnostic testing is required. Lastly, pulmonary function testing (when available), such as spirometry and lung volumes, will distinguish obstructive from restrictive processes. The differential diagnosis of chronic cough is broad, but with the appropriate approach, can be successfully diagnosed and treated.
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The following cases represent less common causes of cough in childhood.