Vocal Cord Dysfunction (VCD): Diagnosis

Based on the symptoms of vocal cord dysfunction (VCD), many people may be misdiagnosed with asthma and treated with asthma medications. Since VCD is not asthma, little or no improvement is seen in symptoms. If VCD is still not diagnosed, oral steroids (used in other chronic lung diseases like severe asthma) may be prescribed. Significant side effects can develop with long-term use of these medicines. Oral steroids are only recommended if it is shown that the benefits of their use outweigh the costs. Additionally, a misdiagnosis can also lead to frequent emergency room visits and hospitalizations - even intubation.

While it should be clear why a correct diagnosis of VCD is important, it is also critical to keep in mind that some people have both VCD and asthma, which complicates both the diagnosis and the treatment.

Breathing tests like spirometry can be useful in diagnosing VCD, but only if they are done when symptoms are occurring. In the absence of any other complicating condition like asthma, breathing tests for VCD will be normal. However, if spirometry is conducted when symptoms are present, and if the doctor obtains what is called a "flow volume loop," VCD will cause a flattening of the inspiratory (and/or expiratory) part of the loop.

And while spirometry is important and useful, a procedure called a laryngoscopy is the most important test in making the diagnosis of VCD. Using a flexible, fiber optic tube and tiny camera inserted into the back of the throat, a specialist can see how the vocal cords open and close. Like spirometry, this test should only be performed when symptoms are present because the vocal cords function normally in the absence of symptoms. Since people with VCD cannot trigger symptoms voluntarily, different tests to trigger symptoms may be required.

This information has been approved by Marcy Hicks, MS, CCC-SLP (July 2006).