AKA paradoxical vocal cord dysfunction,
paradoxical vocal fold motion,
and factitious asthma.
Vocal cord dysfunction is a syndrome in which inappropriate vocal cord motion produces partial airway obstruction, leading to subjective respiratory distress.
When a person breathes normally, the vocal cords move away from the midline during inspiration and only slightly toward the midline during expiration. However, in patients with vocal cord dysfunction, the vocal cords move toward the midline during inspiration or expiration, which creates varying degrees of obstruction.
Patients with vocal cord dysfunction typically present with recurrent episodes of subjective respiratory distress that are associated with inspiratory stridor, cough, choking sensations, and throat tightness.
Laryngospasm - is a subtype of vocal cord dysfunction, is a brief involuntary spasm of the vocal cords that often produces aphonia and acute respiratory distress.
Laryngospasm is a common complication of anesthesia.
Precipitating Factors
Vocal cord dysfunction is associated with a variety of precipitating factors, but no clear unifying pathophysiology has been identified.
Exercise is a common cause of vocal cord dysfunction. Exercise-induced vocal cord dysfunction is often misdiagnosed as exercise-induced asthma. It should be strongly considered in patients with dyspnea on exertion who have been diagnosed with exercise-induced asthma, particularly if they respond poorly to usual treatment with bronchodilators.
Studies have reported associations between vocal cord dysfunction and multiple psychological conditions, including posttraumatic stress disorder, anxiety, depression, and panic attack. Anxiety disorders appear to be particularly common in adolescent patients with vocal cord dysfunction.However, associated depression and anxiety may also be consequences of persistent respiratory symptoms, rather than causes.
Exposure to environmental and occupational irritants has been found to precipitate respiratory symptoms consistent with vocal cord dysfunction. Common airborne irritants associated with vocal cord dysfunction include ammonia, dust, smoke, soldering fumes, and cleaning chemicals. Studies have shown a clear temporal relationship between exposure and onset of symptoms.
Postnasal drip associated with rhinosinusitis has been linked to airway hyperresponsiveness. A high prevalence of rhinosinusitis in patients with vocal cord dysfunction and case reports of resolution of vocal cord dysfunction symptoms with treatment suggest that rhinosinusitis may play a role in some patients.
Gastroesophageal reflux disease (GERD) has been implicated in triggering vocal cord dysfunction. In some studies, a high prevalence of GERD was identified in patients with vocal cord dysfunction; however, treatment of GERD was only effective in decreasing vocal cord dysfunction in some patients.
Neuroleptic drugs, specifically phenothiazines, may cause transient vocal cord dysfunction. This appears to be a focal dystonic reaction and is associated with
extra-pyramidal signs, such as torticollis.
Diagnostic Approaches
The most valuable diagnostic tests for vocal cord dysfunction are pulmonary function testing with a flow-volume loop and flexible laryngoscopy. Other testing, such as measurement of arterial blood gases, may be useful in ruling out other possible diagnoses.
PULMONARY FUNCTION TESTING
Pulmonary function testing with a flow-volume loop is the most commonly used diagnostic test to confirm vocal cord dysfunction. In the flow-volume loop, it is typical for the expiratory loop to be normal and the inspiratory loop to be flattened, which is consistent with an extrathoracic upper airway obstruction
Exercise flow-volume loops, performed in conjunction with exercise testing, may be useful in identifying patients with exercise-induced vocal cord dysfunction.
FLEXIBLE LARYNGOSCOPY
Flexible laryngoscopy is considered the diagnostic standard for vocal cord dysfunction. Direct observation of abnormal vocal cord movement toward the midline during inspiration or expiration confirms the diagnosis. Most patients with symptomatic vocal cord dysfunction will demonstrate the abnormal movement, and more than one half of patients who are asymptomatic will be diagnosed.Stimulating asymptomatic patients with panting, deep breathing, phonating, or exercising may increase the sensitivity of the test.
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