Dyspnea and the Larynx
There are 2 main ways in which patients may experience dyspnea originating in the larynx. First, there may be structural interference with air flow due to an anatomic abnormality. In other words, there is some structural interference with air flow due to a growth, tumor, swelling, anatomical narrowing, etc. The second mechanism by which dyspnea may originate in the larynx is abnormal motion of functioning of a laryngeal structure. This may include problems such as vocal cord dysfunction (VCD), neurologic disorders of the vocal cords, vocal cord paralysis, laryngospasm, etc.
Air Flow Obstruction Resulting From Structural Interference
A number of structural abnormalities may interfere with laryngeal air flow, and may or may not be accompanied by any change in the actual quality of the patient's voice. There are both infectious and noninfectious processes that can lead to air flow obstruction. One of the most rapidly developing and frightening infectious causes of dyspnea originating in the larynx is epiglottitis. Epiglottitis is almost always due to a bacterial pathogen, which may produce rapidly evolving inflammation and edema of the larynx in the supraglottic area. Causative organisms include Haemophilus influenzae type B, Pneumococcus, and group A beta hemolytic streptococci. This most commonly affects children, and may be clinically characterized by drooling, inspiratory stridor, high fever, and airway distress. As noted above, the symptoms may be rapid in onset and progression, and most commonly affect children between the ages of 2 and 8 years, but also may occur in adults.
In a series of 129 cases, approximately 1 out of 7 adults with epiglottitis required airway intervention, by either tracheotomy or endotracheal intubation. In this series, factors that were associated with the need for acute airway intervention were the presence of stridor or having the patient sitting up and erect at the time of presentation. Although there were no deaths, major complications occurred in 5% of patients.
Visualization of the epiglottis is done with either a lateral neck radiograph or using a flexible fiberoptic rhinolaryngoscope via a nasal approach. A tongue blade is never used when epiglottitis is suspected because of the risk of precipitating acute airway closure. Medical management of acute epiglottitis involves the use of appropriate antibiotic therapy and, in some patients, corticosteroids. The immediate availability of medical personnel capable of securing an airway is also crucial, since tracheotomy or endotracheal intubation may be needed in the management of the patient. If a patient's symptoms are escalating rapidly, it is better to secure an airway sooner rather than later in this potentially life-threatening situation.
The subglottic area may also be affected by viral infections, such as croup. Croup is commonly caused by a viral pathogen, frequently influenza or parainfluenza virus. Although croup is not a typical laryngeal cause of dyspnea, nonetheless, it is an important cause of stridor in children, with treatment consisting of hydration, humidification, corticosteroids, and racemic epinephrine in some patients.
Bacterial tracheitis may be fatal, and typically presents with high fever, stridor, a barking cough, extreme leukocytosis, and thick mucopurulent discharge from the trachea. Staphylococcus is a frequent causative organism, although H influenza type B and group A streptococci have also been reported to cause this condition. Occasionally, intubation and tracheostomy may be needed in these patients, and therapeutic intervention with antibiotics must be done without delay to minimize the need for acute airway intervention.
Infections may also result in laryngeal abscesses, including those in both the larynx or hypopharyngeal area, and may compromise the airway, requiring surgical incision and drainage. These abscesses may occur following an episode of tonsillitis, and may be deceptively slow in their evolution. Finally, there are a number of less common infectious diseases that may involve the larynx, including tuberculosis, syphilis, trichinosis, diphtheria, histoplasmosis, and leprosy. Fungal infections may also involve the laryngeal airway, including infections with Aspergillus, Histoplasma, Coccidioides, Blastomyces, Actinomyces, Candida, Cryptococcus, and Nocardia.
Both benign and malignant tumors of the larynx may also lead to shortness of breath; again, direct visualization is mandatory to accurately diagnose these disorders. The most common benign tumor of the larynx is squamous papilloma, which may occur either in a juvenile or adult form. It is seen in a higher frequency in children who are delivered vaginally from mothers who have venereal warts and are infected with the human papilloma virus. In this case, presenting symptoms may include hoarseness, respiratory compromise, or audible stridor. If untreated, this condition can result in fatal asphyxiation, and this has been reported in children. This condition is difficult to treat, and a number of approaches have been used, including carbon dioxide laser, systemic interferon, and others. It is most important to refer such patients to an otolaryngologist for appropriate management.
Noninfectious Causes of Laryngeal Air Flow Limitation
Appropriate air flow through the larynx may be impeded by a number of noninfectious conditions. The most common cause of stridor in children is congenital laryngomalacia. This is a condition that results from a flaccidity of the larynx. A lack of rigidity of the framework that supports the larynx leads to this condition, in concert with some accompanying flaccidity of the supraglottic tissues of the larynx. Increased physician activity may lead to stridor, as may crying in infants. The symptoms may occur in infants and young children as early as a few weeks after birth and may last from 12 to 18 months. Direct visualization of the larynx may show a converging of the laryngeal structures during inspiration, and although the disorder usually spontaneously resolves in time, tracheostomy may be indicated in severe cases.
A narrowing of the area just beneath the true vocal cords is referred to as subglottic stenosis. This may occur from a number of causes, including trauma to the larynx from prolonged endotracheal intubation. In addition, this narrowing may occur from vasculitic or other inflammatory conditions such as Wegener's granulomatosis, relapsing polychondritis, or systemic lupus erythematosus. The differential diagnosis of subglottic stenosis includes infection, tumor, trauma, thermal or chemical inhalation, live/acid ingestion, and tracheomalacia. In addition, sarcoidosis and amyloidosis may also cause inflammatory changes or masses within the larynx.
An acute allergic reaction, such as anaphylaxis to food, insect sting, drug, or other cause, may also lead to laryngeal edema. Idiopathic angioedema, outside of the setting of acute anaphylaxis, may also lead to laryngeal swelling and may occur as either an idiopathic condition or as the hereditary form of C-1 esterase inhibitor deficiency. Prompt administration of subcutaneous epinephrine, systemic corticosteroids, and maintenance of an adequate airway are crucial in the management of acute laryngeal edema.
In young children or toddlers with stridor, the question of foreign body aspiration frequently arises. The peak incidence of foreign body aspiration occurs between the ages of 12 and 36 months. In young children, the larynx is very pliable and is located in close proximity to the esophagus. Because of this fact, foreign bodies lodged within the esophagus may actually lead to respiratory compromise and stridor in young children. Elderly patients, especially those who are debilitated or have any type of swallowing dysfunction, may also suffer from foreign body aspiration. Those who have degenerative neurologic disease or have experienced a cerebrovascular accident may be at especially high risk.
Finally, other noninfectious causes of laryngeal airway obstruction may include vocal cord polyps, laryngoceles, saccular cysts, and laryngeal vascular malformations. Goiters involving the cervical and substernal area may also interfere with tracheal and laryngeal air flow.
The flow volume loop may be somewhat helpful in alerting a physician to a structural interference with air flow. A flattening of the inspiratory portion of the flow volume loop may suggest a variable extrathoracic obstruction, whereas a flattening of the expiratory portion may suggest a variable intrathoracic obstruction. Flattening of both the inspiratory and expiratory limbs raises the suspicion of a fixed airway narrowing.
Medscape Allergy & Immunology. 2002;2(2) © 2002 Medscape
Cite this: Dyspnea Due to Vocal Cord Dysfunction and Other Laryngeal Sources - Medscape - Aug 01, 2002.