Dyspnea Due to Vocal Cord Dysfunction and Other Laryngeal Sources

Mark T. O'Hollaren, MD

Disclosures

August 26, 2002

In This Article

Diagnosis of VCD

When interviewing a patient, a careful history may give some clues as to the correct diagnosis. Patients may point to their larynx when asked where they feel the site of air flow limitation exists, and may describe a sense of throat tightness or even changes in their voice during an acute attack. Kenneth B. Newman, MD,[7] Medical Director of Respiratory Products of Forest Laboratories, Inc. in New York, NY, stated at the 58th Annual Meeting of the American Academy of Allergy, Asthma and Immunology that perhaps the most reliable question to ask a patient is whether they feel inhaled bronchodilators improved their breathing or not. Especially in patients with isolated VCD without asthma, bronchodilators have little benefit. Another important question is whether they experience dyspnea accompanying these episodes and waking them up at night. Nocturnal symptoms of shortness of breath are fairly common in patients with asthma, and are rare in patients with VCD.

The physical examination of patients with VCD may be very unreliable. Because sounds may be transmitted throughout the chest through the excellent sound-conducting properties of the large airways, it is difficult to localize the site of origin for wheezing or stridor sounds. If a patient is suspected of having VCD, then the gold standard is direct visualization of the larynx during an acute attack to confirm that the vocal cords approximate during inspiration, during expiration, or both. The term "paradoxical vocal cord motion" is typically given to patients who have approximation of the vocal cords during an inspiratory maneuver, since the vocal cords typically abduct, or widen, during inspiration in patients without the VCD. Another potentially helpful diagnostic tip when suspecting VCD is to have the patient hold their breath or to use a panting pattern of breathing. Patients with acute asthma find it very difficult to hold their breath, although those with VCD may be able to do so more readily. This action may actually improve their symptoms of dyspnea. In addition, patients with VCD may have decreased symptoms of dyspnea if they breathe in a panting fashion.

Patients with VCD may have a flattening of the inspiratory portion of the flow volume loop, consistent with variable extrathoracic obstruction. Dr. Newman described approximately 25% of patients who may have an abnormal inspiratory portion of the flow volume loop, even when asymptomatic.

Another clue that a patient's dyspnea may be caused by VCD is that during an attack, the patient's alveolar-arterial (A-a) oxygen gradient is frequently normal.[8] In contrast, patients experiencing acute severe asthma will have a widening of the A-a oxygen gradient in greater than 90% of cases. Flow volume loop during the acute attack may also show some inspiratory flattening consistent with variable extrathoracic obstruction, but, alternatively, the flow volume loop may show both inspiratory and expiratory flattening more consistent with fixed obstruction. It should be pointed out, however, that virtually any type of air flow abnormality pattern could be present during an acute attack of VCD.

Laryngoscopic Findings With VCD

As discussed earlier, inspiration typically results in the widening of the glottic aperture. During VCD, there tends to be an inappropriate adduction of the anterior two thirds of the vocal cords, with the posterior one third typically remaining slightly open in a "diamond-shaped chink" pattern. This may occur during inspiration only, during both phases of respiration, or during expiration only. If needed, provocative challenges using exercise or other stimuli may be done where laryngoscopic confirmation of the diagnosis may be accomplished.

Other Contributing Factors

Psychological stress may also play a role in some patients with VCD. Clinical experience of those treating VCD has shown that stressful situations, especially in adolescent high-performance female athletes, may increase the chance that VCD may be playing a role in some patients with dyspnea, which do not respond to typical treatment for exercise-induced asthma. It is appropriate to consider each individual case, and explore areas of psychological difficulty that may be compounding a given patient's clinical presentation. There have been some reports of association of VCD with psychological trauma as well, including a past history of sexual abuse, although this appears to be only evident in a minority of patients. A retrospective review by Freedman and coworkers[9] of 47 female inpatients at National Jewish Center with discharge diagnoses of VCD showed that 36% of those patients had experienced childhood sexual abuse. This should be kept in the context that the prevalence of sexual abuse in the general female population ranges from 6% to 62%.[10] The prevalence of sexual abuse in patients with VCD may not, therefore, represent a defining characteristic of this population. It is clear that unrecognized and untreated psychological problems may, in fact, be associated with VCD and should be addressed as appropriate.

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