title: Vocal cord dysfunction: an important differential diagnosis of bronchial asthma.
abstract: BACKGROUND
  Intermittent paradoxical closure of the vocal cords can induce major attacks of dyspnea. Such attacks, called "vocal cord dysfunction" (VCD), are an important element in the differential diagnosis of intractable bronchial asthma.
  
  
  METHODS
  Selective review of the literature.
  
  
  RESULTS
  The etiology of VCD is unclear. Its clinical manifestations can mimic those of bronchial asthma. Standard asthma medication fails to improve the dyspnea of VCD, which is subjectively perceived as life-threatening. Consequently, patients with unrecognized VCD may be treated with very high doses of anti-asthmatic medication, including systemic corticosteroids, leading to major iatrogenic morbidity. No prospective studies are available on this subject to date. Experts estimate that 3% to 5% of persons diagnosed as having bronchial asthma actually suffer from VCD. Because of the brevity of the attacks, which usually last only 1-2 minutes, VCD is difficult to diagnose with the methods generally used to diagnose asthma. Evidence-based therapeutic approaches are still lacking, but speech therapy, including special breathing techniques with relaxation of the throat, seems to control the attacks of dyspnea in most patients.
  
  
  CONCLUSIONS
  An improved knowledge of the clinical manifestations of VCD can help physicians diagnose it correctly. Early diagnosis can prevent prolonged erroneous treatment based on a false diagnosis of bronchial asthma and thereby obviate the iatrogenic side effects of long-term corticosteroid therapy, as well as the resulting economic losses.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kenn
authors.forename: Markus M
authors.initials: MM
authors.lastname: Hess