Vocal cord dysfunction in adolescents

Abstract

Background: Vocal cord dysfunction (VCD) often presents with dramatic and abrupt symptoms. To diagnose VCD, visualisation by direct laryngoscopy is required and usually a specific method to provoke VCD is needed.

Objectives: Adolescents with clinical suspicion of VCD were invited to participate. The first objective was to diagnose VCD, second objectives were changes of pulmonary function test (PFT) and predictors of VCD before and after methacholine challenge test (MCT).

Methods: After an initial PFT, a direct laryngoscopy was performed. This was followed by the MCT; the endpoint was the methacholine dose causing a 20% drop of the forced expiratory volume in one second (PD₂₀FEV₁). After that a second laryngoscopy was conducted. PFT changes before and after MCT were compared with the data of 14 healthy controls (HC).

Results: Thirty-five patients (8-19 years) were investigated. Three failed to have a significant reaction to methacholine and three showed anatomical alterations. Of the remaining 29 patients, 14 had VCD and 15 had bronchial hyperresponsiveness (non-VCD). PD₂₀FEV₁ methacholine was significant lower in VCD compared with non-VCD (VCD 0.24 mg ± 0.4, non-VCD 0.73 mg ± 0.73, p= 0.0006). VCD patients showed significantly lower PFT parameters after MCT; FEV₁: VCD 58.5% ± 20.1, non-VCD 77.8% ± 18.4, and HC 98.7% ± 16.6 (p< 0.0001); inspiratory vital capacity (IVC): VCD 61.3% ± 20.9, non-VCD 75.7% ± 14.8, and HC 101.1% ± 15.4 (p= 0.0004).

Conclusions: The combination of MCT and laryngoscopy may be able to differentiate between VCD and non-VCD patients. VCD patients showed a positive reaction at lower methacholine doses and had a higher airway obstruction. PFT and MCT do not replace direct laryngoscopy in the diagnosis of VCD in adolescents.