Post-COVID-19 Vocal Cord Dysfunction

Vocal cord dysfunction/inducible laryngeal obstruction induced by hyperventilation in healthy individuals, people with asthma, and following coronavirus infection

OBJECTIVE

Vocal cord dysfunction/inducible laryngeal obstruction (VCD/ILO) commonly co-exists with asthma and can start after viral infections. In this setting evidence suggests that dysfunctional breathing may induce the disorder but this possibility has not been researched. We therefore postulated that dysfunctional breathing can induce VCD/ILO, more so in people with asthma and after viral infections.

METHODS

Eight healthy control subjects, 16 people with asthma and eight people who had recent COVID-19 infection (three with asthma) were recruited. Video-recorded laryngoscopy was performed at tidal breathing and during controlled hyperventilation (used as a proxy for dysfunctional breathing). VCD/ILO was diagnosed by laryngoscopy using accepted criteria and correlated with study cohorts, clinical attributes, asthma severity and spirometry.

RESULTS

Overall, 32 subjects were studied. Hyperventilation was verified in all subjects. None of the healthy control group or people with mild asthma developed VCD/ILO during or after hyperventilation but one person with moderate/severe asthma had clear evidence of VCD/ILO. In contrast, in people who had COVID-19 infection, hyperventilation induced VCD/ILO in 3/8 people (38%).

CONCLUSION

These proof-of-concept studies suggest that hyperventilation can provoke VCD/ILO in asthma and after a recent viral infection. How and why VCD/ILO develops is not known and these preliminary findings should prompt further studies of links between dysfunctional breathing, asthma, and viral infections.

Infections including SARS-CoV-2 as triggers for vocal cord dysfunction

Vocal cord dysfunction (VCD) is often under-recognized and/or misdiagnosed as asthma. Although post-viral syndrome has been suggested as a contributing factor in VCD, there is limited data on infection-associated VCD. The purpose of this study was to assess and describe the proportion of patients who were diagnosed with VCD who did and did not report infection preceding VCD diagnosis. Subjects age ≥ 12 years referred for VCD assessment at the time of provocation challenge-rhinolaryngoscopy were enrolled in this prospective study of triggers for VCD registry. Enrollment initiated September 2021. An investigator designed questionnaire of potential triggers for VCD including SARS-CoV-2 was administered with medical data collection using REDCap software platform. Characteristics of subjects with and without respiratory infection-associated VCD were analyzed using Chi-square test and Student’s t-test. Of the 54 subjects analyzed, 57.4% (N=31) reported infection-associated VCD symptoms with either 1) VCD onset following respiratory infection (N=18, 33.3%) or 2) VCD symptoms worsened following SARS-CoV-2 infection (N=13, 24.1%). Subjects with infection-associated and non-infection-associated VCD otherwise shared largely similar characteristics. There were more subjects being age greater than 40 years in the infection-associated group (p=0.027) and this group also reported more throat clearing (p=0.019). Our results suggest a role for infectious etiologies, including SARS-CoV-2, in triggering and/or worsening VCD. VCD should be considered in the differential diagnosis of protracted shortness of breath following SARS-CoV-2 and other respiratory infections.

Diagnosis of vocal cord dysfunction/inducible laryngeal obstruction: An International Delphi Consensus Study

BACKGROUND

Vocal cord dysfunction/inducible laryngeal obstruction (VCD/ILO) is characterized by breathing difficulties in association with excessive supraglottic or glottic laryngeal narrowing. The condition is common and can occur independently; however, it may also be comorbid with other disorders or mimic them. Presentations span multiple specialties and misdiagnosis or delayed diagnosis is commonplace. Group-consensus methods can efficiently generate internationally accepted diagnostic criteria and descriptions to increase clinical recognition, enhance clinical service availability, and catalyze research.

OBJECTIVES

We sought to establish consensus-based diagnostic criteria and methods for VCD/ILO.

METHODS

We performed a modified 2-round Delphi study between December 7, 2021, and March 14, 2022. The study was registered at ANZCTR (Australian New Zealand Clinical Trials Registry; ACTRN12621001520820p). In round 1, experts provided open-ended statements that were categorized, deduplicated, and amended for clarity. These were presented to experts for agreement ranking in round 2, with consensus defined as ≥70% agreement.

RESULTS

Both rounds were completed by 47 international experts. In round 1, 1102 qualitative responses were received. Of the 200 statements presented to experts across 2 rounds, 130 (65%) reached consensus. Results were discussed at 2 international subject-specific conferences in June 2022. Experts agreed on a diagnostic definition for VCD/ILO and endorsed the concept of VCD/ILO phenotypes and clinical descriptions. The panel agreed that laryngoscopy with provocation is the gold standard for diagnosis and that ≥50% laryngeal closure on inspiration or Maat grade ≥2 define abnormal laryngeal closure indicative of VCD/ILO.

CONCLUSIONS

This Delphi study reached consensus on multiple aspects of VCD/ILO diagnosis and can inform clinical practice and facilitate research.