ESTES PARK, COLO. (FRONTLINE MEDICAL NEWS)Consider the possibility of comorbid vocal cord dysfunction in patients with asthma that doesn’t respond to aggressive therapy

“Vocal cord dysfunction is an important diagnosis. It’s something to think about in your toughest-to-treat asthma patients. I think you’ll see a lot of it,” Dr. Robert L. Keith predicted at a conference on internal medicine sponsored by the University of Colorado.

Vocal cord dysfunction (VCD) is defined as adduction or closure of the vocal cords on inspiration or exhalation. VCD is a notorious mimicker of asthma. The two conditions share many signs and symptoms, including wheezing, shortness of breath, cough, chest tightness, stridor, and throat tightness, noted Dr. Keith, professor of medicine in the department of pulmonology and critical care medicine at the university.

In a classic study, investigators at National Jewish Health in Denver found that among patients referred to the tertiary center for asthma who had failed to respond to conventional therapies, 30% turned out to have asthma plus VCD and another 10% actually had VCD alone (Semin Respir Crit Care Med 1994;15(2):161-67).

The diagnosis of VCD is suggested by worsening symptoms upon bronchoprovocation during pulmonary function testing, with no change in forced expiratory volume in 1 second (FEV1) or PC20, which is the dose of the provocative inhalational agent required to produce a 20% drop in FEV1.

“You can think of VCD as extrathoracic obstruction,” Dr. Keith said.

Definitive diagnosis of VCD is made by direct fiber optic laryngoscopy carried out with no sedation, which would affect the vocal cords. Look for abnormal vocal cord movements during a variety of patient maneuvers, including panting and full inhalation and exhalation, Dr. Keith advised.

The cornerstone of VCD treatment is specific breathing exercises which were pioneered by and are still typically led by speech therapists. Hypnosis, biofeedback, and psychotherapy can be helpful. Patients experiencing a severe acute attack obtain benefit from inhaling a helium/oxygen mixture.

Injection of botulinum toxin or sectioning of the laryngeal nerve in order to affect vocal cord movement are other options, although Dr. Keith said he has never found it necessary to refer patients with VCD for those therapies.