Published online: March 12, 2020
Some patients with asthma continue to have poor disease control despite maximal inhaled controller medication ─ termed “difficult-to-treat” asthma. Some of these patients have concurrent vocal cord dysfunction (VCD), where symptoms attributed to asthma are actually caused by inappropriate narrowing of the vocal cords during respiration. The hallmark of this is paradoxical vocal fold motion (PVFM), visualized on direct laryngoscopy. Why VCD occurs in difficult-to-treat asthma, and which clinical features best predict its presence, are important unanswered questions.
In a recent article published in The Journal of Allergy & Clinical Immunology: In Practice, Lee and colleagues examined a consecutive series of patients with difficult-to-treat asthma undergoing multidisciplinary systematic assessment at their referral center. Patients with suspected vocal cord dysfunction underwent laryngoscopy for diagnostic confirmation. Relationships between VCD and clinical factors (demographics, asthma parameters and other comorbidities) were identified using multiple logistic regression.
Among 169 consecutive patients, 32 (19%) had laryngoscopic evidence of VCD. These patients had less airway obstruction and less eosinophilic inflammation, despite similar levels of asthma exacerbations, symptom control and quality of life to the other patients. On multivariate analysis, physiotherapist-diagnosed dysfunctional breathing (adjusted OR 4.93, 95% CI 2 -12, p<0.001) and preserved lung function (adjusted OR 1.067 95%CI (1.028 -1.106 p<0.001) were independently associated with VCD.
This study supports a relationship between VCD and dysfunctional breathing, a term which describes abnormal breathing patterns encompassing hyperventilation, periodic deep sighing, upper chest predominant breathing, and asynchronous breathing. This relationship raises the possibility of shared pathogenic pathways between the 2 conditions. The co-existence of both conditions in patients with difficult-to-treat asthma may compound the burden of asthma symptoms. Since patients with VCD had better lung function than those without VCD, it is unlikely that airflow obstruction per se induces VCD.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.