Overview
Definition:
Vocal Cord Dysfunction (VCD) is a condition characterized by the inappropriate adduction of the vocal cords during inspiration, leading to upper airway obstruction
Asthma is a chronic inflammatory disease of the airways characterized by reversible bronchoconstriction, airway hyperresponsiveness, and inflammation.
Epidemiology:
VCD is often misdiagnosed as asthma and may affect up to 10-15% of patients with difficult-to-control asthma
It is more common in adolescents and young adults, with a female predominance
Prevalence in pediatric populations is not precisely defined but is increasingly recognized.
Clinical Significance:
Accurate differentiation is crucial as management strategies differ significantly
Misdiagnosis of VCD as asthma can lead to unnecessary, ineffective treatments with inhaled corticosteroids and bronchodilators, while delaying appropriate VCD management such as voice and breathing therapy.
Clinical Presentation
Symptoms:
VCD: Sudden onset of dyspnea, often with stridor or a sensation of throat tightness
Symptoms are typically acute and episodic, often triggered by exercise, stress, or irritants
May report cough and hoarseness
Asthma: Chronic cough, wheezing, shortness of breath, and chest tightness, often nocturnal or early morning
Symptoms can be persistent or intermittent.
Signs:
VCD: Inspiratory stridor, paradoxical vocal cord movement on laryngoscopy, sometimes inspiratory wheezing that may disappear with forced expiration
Asthma: Expiratory wheezing, decreased breath sounds, tachypnea, accessory muscle use
Auscultation may be normal between exacerbations.
Diagnostic Criteria:
VCD: Diagnosis is primarily clinical, confirmed by laryngoscopy showing inspiratory vocal cord closure
No specific laboratory markers
Asthma: Diagnosis based on history, physical exam, and confirmation of variable airflow obstruction and airway hyperresponsiveness via spirometry or other lung function tests.
Diagnostic Approach
History Taking:
Key history points include the nature of dyspnea (inspiratory vs
expiratory), presence of stridor, hoarseness, triggers (exercise, emotional stress), and response to asthma medications
Red flags for VCD include lack of response to bronchodilators and corticosteroid therapy, and presence of stridor.
Physical Examination:
Focus on respiratory effort, presence of stridor, wheezing, and vocal quality
During an acute episode, careful observation of inspiratory vs
expiratory effort is key
Observe for paradoxical vocal cord movement if possible during speaking or breathing exercises.
Investigations:
Spirometry: In asthma, spirometry shows reversible airflow obstruction (increase in FEV1 by >12% and >200 mL after bronchodilator)
In VCD, spirometry may be normal or show variable obstruction, often with reduced inspiratory flow
Flow-volume loops in VCD typically show flattening of the inspiratory limb
Laryngoscopy: Direct visualization is the gold standard for VCD, showing paradoxical adduction of the vocal cords during inspiration
Can be performed during a symptomatic episode or with specific provocative maneuvers.
Differential Diagnosis:
Other causes of stridor and dyspnea in children: croup, epiglottitis, foreign body aspiration, tracheomalacia, laryngomalacia
In older children and adolescents, consider psychogenic cough, habit cough, and anxiety-related hyperventilation
Differentiating VCD from asthma is critical due to different management.
Management
Initial Management:
For acute VCD exacerbation, calm reassurance and guidance on breathing techniques are paramount
Avoid bronchodilators or corticosteroids unless there is a concurrent diagnosis of asthma
For acute asthma exacerbations, administer short-acting beta-agonists and consider systemic corticosteroids.
Medical Management:
Medical management for VCD is not based on pharmaceuticals but on behavioral and speech therapy
Voice and breathing exercises focus on diaphragmatic breathing, vocal cord abduction techniques, and stress management
Management for asthma involves inhaled corticosteroids, bronchodilators, and potentially leukotriene modifiers.
Surgical Management:
Surgical management is generally not indicated for VCD
In rare, severe refractory cases, options might be explored, but conservative management is preferred
No specific surgical interventions for typical VCD in pediatrics.
Supportive Care:
Education of the patient and family is crucial
Identifying triggers and developing coping strategies for VCD is important
For asthma, supportive care includes ensuring adherence to medication, education on inhaler technique, and prompt management of exacerbations.
Complications
Early Complications:
VCD: Prolonged episodes of severe dyspnea, anxiety, and potential for misdiagnosis leading to delayed appropriate care
Asthma: Respiratory failure, status asthmaticus, pneumothorax during severe exacerbations.
Late Complications:
VCD: Chronic throat discomfort, vocal strain, and persistent anxiety related to breathing
Asthma: Airway remodeling, chronic airflow limitation, reduced quality of life, frequent hospitalizations.
Prevention Strategies:
VCD: Early diagnosis and initiation of speech and breathing therapy
Identifying and avoiding triggers
Asthma: Strict adherence to controller medications, trigger avoidance, regular medical follow-up, and asthma education programs.
Prognosis
Factors Affecting Prognosis:
For VCD, prognosis is generally good with consistent participation in speech and breathing therapy
Factors influencing success include patient motivation and identification of underlying triggers
For asthma, prognosis depends on disease severity, adherence to treatment, and control of exacerbations.
Outcomes:
VCD: Many patients experience significant symptom improvement and resolution with appropriate therapy
Asthma: With good control, children can lead normal lives
however, severe or poorly controlled asthma can lead to long-term lung damage and reduced function.
Follow Up:
Patients with VCD benefit from regular follow-up with speech therapists and potentially pulmonologists to monitor progress and reinforce techniques
Asthma patients require regular follow-up to assess control, adjust therapy, and monitor lung function.
Key Points
Exam Focus:
The key differentiating feature between VCD and asthma lies in the pattern of dyspnea and the findings on laryngoscopy (paradoxical vocal cord movement in VCD) and spirometry (inspiratory stridor/flattening of inspiratory limb in VCD vs
reversible expiratory obstruction in asthma).
Clinical Pearls:
Always consider VCD in children with apparent asthma that is refractory to standard treatment, especially if stridor or hoarseness is present
The flow-volume loop is a valuable tool in differentiating obstructive disorders.
Common Mistakes:
Over-reliance on spirometry alone without considering laryngoscopy findings for VCD
Misinterpreting normal spirometry in VCD as ruling out airway disease
Treating VCD with inhaled corticosteroids and bronchodilators, which are ineffective and delay appropriate management.