Chest
Volume 122, Issue 6, December 2002, Pages 1988-1993
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Clinical Investigations: Asthma
Vocal Cord Dysfunction Induced by Methacholine Challenge Testing

https://doi.org/10.1378/chest.122.6.1988Get rights and content

Study objectives

To determine whether methacholine challenge testing (MCT) provokes vocal cord dysfunction (VCD), as evidenced by inspiratory vocal cord closure on direct laryngoscopy, and whether spirometry and flow-volume loops (FVLs) demonstrate any changes that are suggestive of VCD.

Design

Prospective, controlled study.

Setting

Army medical center.

Patients

Thirty-four subjects all with normal baseline spirometry. Ten subjects had documented evidence of VCD, 12 subjects had exercise-induced asthma (EIA) and reactive MCT, and 12 subjects served as healthy asymptomatic control subjects.

Methods

Measurement of spirometry with FVLs and direct laryngoscopy of the vocal cords performed immediately before and after subjects had undergone MCT.

Results

Evidence of inspiratory vocal cord adduction was found in four VCD patients. Two patients had adducted vocal cords at baseline, and their conditions were unchanged after undergoing MCT. Two other patients had normal conditions at baseline and demonstrated acute inspiratory vocal cord adduction after undergoing MCT. None of the patients in the EIA or control groups had evidence of VCD at baseline or after undergoing MCT. Truncation of the inspiratory limb of the FVL after MCT was noted in five patients, which correlated with evidence of VCD in 60% of these patients. One EIA patient had truncation of the inspiratory FVL after MCT, and no changes were found in the control group. A comparison of spirometry between EIA patients and VCD patients with and without evidence of inspiratory vocal cord adduction during MCT showed no significant differences.

Conclusions

The findings suggest that MCT may cause an acute episode of vocal cord adduction and that positive results may not reflect underlying reactive airways disease. However, a flattening or truncation of the inspiratory FVL after the patient undergoes MCT is not diagnostic for the presence of inspiratory vocal cord adduction.

Section snippets

Materials and Methods

The institutional review board approved this study protocol, and each patient signed an informed consent for participation in the study. Three groups of patients were enrolled. The first group consisted of asymptomatic control subjects who had been recruited from among active-duty Army personnel and were able to complete the Army 2-mile run in > 75% of the minimum standard. These subjects were required to have normal baseline spirometry and FVL values prior to enrollment. The second group

Results

A total of 34 patients were enrolled in the protocol. The VCD group (n = 10) consisted of two men and eight women with an average age (± SD) of 31.1 ± 15.6 years. The majority of patients had symptoms of exertional dyspnea as their presenting complaint prior to receiving a diagnosis of VCD. Two other patients had a history of poorly controlled asthma and gastroesophageal reflux disease. The demographics for each patient are shown in Table 1. The EIA group (n = 12) consisted of four men and

Discussion

VCD is a well-recognized cause of dyspnea, wheezing, and inspiratory stridor. Numerous case series and anecdotal reports describe how frequently VCD is incorrectly diagnosed and patients are treated for asthma. It becomes very important for the clinician to document the presence of airway hyperresponsiveness to help differentiate between VCD and asthma. However, the extent to which these two syndromes overlap has not been investigated previously. Our present study directly examined vocal cord

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  • Cited by (0)

    The opinions or assertions contained herein are the private views of the authors and are not to be construed as reflecting the opinion of the Department of the Army or the Department of Defense.

    MAJ Perkins was awarded the 2000 CHEST Foundation Young Investigator Award, at Chest 2000, San Francisco, CA, October 22 to 26, 2000.

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