Vocal cord dysfunction (VCD) and dysfunctional breathing (DB) disorders may mimic or coexist with asthma, leading to overtreatment with corticosteroids with consequent morbidity. Iatrogenic complications can be averted by early and correct diagnosis. VCD, also termed paradoxical vocal fold motion disorder (PVFMD), is characterized by intermittent paradoxical adduction of the vocal cords, mainly during inspiration, leading to airflow obstruction and dyspnea. Patients with VCD may have repetitive emergency room visits due to acute dyspnea (mimicking exacerbations of asthma). In the seminal descriptions of VCD, young women (often with psychiatric issues) predominated; however, other groups at increased risk for developing VCD include elite athletes, military recruits, and individuals exposed to irritants (inhaled or aspirated). Chronic postnasal drip, laryngopharyngeal reflux (LPR), and gastroesophageal reflux (GER) may lead to laryngeal hyperresponsiveness. The diagnosis of VCD may be difficult because physical exam and spirometry may be normal between episodes. During symptomatic episodes, spirometry typically reveals variable extrathoracic airway obstruction (truncated inspiratory flow volume loop). The gold standard for identifying VCD is flexible fiberoptic rhinolaryngoscopy. Management of VCD includes identification and treatment of underlying disorders (eg, chronic postnasal drip, LPR, GER, anxiety, depression) and a multidisciplinary approach (including highly trained speech therapists). Speech therapy and biofeedback play a critical role in teaching techniques to override various dysfunctional breathing habits. When postnasal drip, LPR, or GER coexist, these disorders should be aggressively treated. With successful therapy, corticosteroids can often be discontinued. During severe, acute episodes of VCD, therapeutic strategies include heliox (80% helium/20% oxygen), topical lidocaine, anxiolytics, and superior laryngeal blocks with Clostridium botulinum toxin. DB is a poorly understood disorder with features that overlap with VCD and asthma. The dysfunctional pattern may reflect abnormalities in the rate or depth of breathing or in breathing mechanics that may involve the nasal passages, oropharynx, larynx, or chest wall muscles. Not unlike VCD, patients with DB are often diagnosed with asthma, and their symptoms do not improve on asthma medicines. There is no consensus regarding diagnostic criteria or appropriate testing for DB. The pathophysiology of DB is poorly understood, but psychological or physiological stress may precipitate episodes in some patients. Treatment requires a multidisciplinary approach (including speech therapy and psychological support). Prognosis is usually good.
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