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Vocal cord dysfunction often
mimics asthma. VCD is characterized by episodic dyspnea and
wheezing caused by intermittent paradoxical vocal cord adduction
during inspiration (sometimes with abnormal adduction during
expiration as well). The cause of VCD is not well understood,
although some patients develop VCD in response to irritant
triggers, such as fumes, cold air, and exercise. Although VCD is
clearly distinct from asthma, it is often confused with asthma,
leading to inappropriate medication of affected individuals with
anti-asthma medications.
Asthma medications typically do little, if anything, to relieve
symptoms if the patient has pure VCD. VCD should be considered
in the differential of difficult-to-treat, atypical asthma
patients.
It is important to note, however, that VCD and asthma may
coexist and that VCD may complicate asthma management. Elite
athletes, in particular, are prone to both exercise induced
bronchospasm (EIB) and VCD, so careful workup is warranted for
athletes who present with exercise-related breathlessness
(Rundell and Spiering 2003).
During severe VCD episodes, respiratory distress may be severe
and lead to intubation. Once the trachea is intubated, the
wheezing and distress abate in VCD but not in
asthma.
VCD can be difficult to diagnose. Variable flattening of the
inspiratory flow loop on spirometry is strongly suggestive of
the diagnosis, but abnormalities of the inspiratory loop may
well be absent between episodes.
The diagnosis of VCD comes from indirect or direct vocal cord
visualization during an episode, during which the abnormal
adduction can be documented.
Therapy generally consists of speech therapy and relaxation
techniques (Bucca et al. 1995; Christopher et al. 1983; Newman
et al. 1995).
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