Vocal cord dysfunction induced by methacholine challenge testing.
OBJECTIVE
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.


METHODS
Prospective, controlled study.


METHODS
Army medical center.


METHODS
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.
Perkins
Patrick J
PJ
Pulmonary Disease/Critical Care Service, Department of Medicine, Brooke Army Medical Center, 3581 Roger Brooke Drive, Fort Sam Houston, TX 78234-6200, USA. Patrick.Perkins@cen.amedd.army.mil
Morris
Michael J
MJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D001250:Asthma, Exercise-Induced / Q000175:diagnosis; D005260:Female; D006801:Humans; D007818:Laryngeal Diseases / Q000139:chemically induced / Q000175:diagnosis; D007828:Laryngoscopy; D008297:Male; D016210:Methacholine Chloride / Q000009:adverse effects*; D011446:Prospective Studies; D013147:Spirometry; D014827:Vocal Cords / Q000187:drug effects / Q000503:physiopathology
D016210:Methacholine Chloride