What is the likely diagnosis for a teenage girl with shortness of breath, chest pain, and voice loss during exercise, inconsistent spirometry findings, no atopy, and a family history of vocal cord dysfunction (VCD), considering both Exercise-Induced Asthma (EIA) and VCD?

Vocal Cord Dysfunction is the Primary Diagnosis

This teenage girl most likely has exercise-induced laryngeal dysfunction (EILD), specifically vocal cord dysfunction (VCD), possibly with coexisting exercise-induced bronchoconstriction (EIB), and you should proceed directly to flexible laryngoscopy during exercise challenge to confirm the diagnosis. 1

Clinical Profile Strongly Suggests VCD

Your patient's presentation is classic for VCD in several key ways:

• Demographics match perfectly: VCD is most common in middle school to high school-aged athletes, particularly young females 1
• Voice loss during exercise is a hallmark feature of EILD/VCD, not of EIB 1
• Family history of vocal abnormalities ("talk funny," "weak voice") suggests a familial laryngeal structural or functional predisposition that strongly points toward VCD rather than asthma 2
• Absence of atopy makes classic allergic asthma less likely 3

Timing and Symptom Pattern Are Diagnostic

The critical distinguishing features between EIB and VCD are temporal:

• VCD symptoms occur and peak DURING exercise, resolving within approximately 5 minutes of stopping 1
• EIB symptoms peak 5-20 minutes AFTER exercise cessation and involve expiratory rather than inspiratory symptoms 1
• Your patient's voice loss and shortness of breath during exercise align with VCD, not EIB 4

Inconsistent Spirometry Findings Support VCD

The variability in spirometry results is characteristic of VCD:

• VCD findings are only present during symptomatic periods, explaining why spirometry can be completely normal at times 1
• When symptomatic, look for flattening or truncation of the inspiratory portion of the flow-volume loop, which is the spirometric hallmark of VCD 1
• The inconsistent small airway obstruction you're seeing may represent either intermittent VCD or coexisting EIB 1

Both Conditions Can Coexist

A critical pitfall to avoid:

• EILD can occur alone OR with EIB - they are not mutually exclusive 1
• Studies show that 26% of uncontrolled asthmatics with unexplained dyspnea have coexisting IEVCD 5
• Failure to respond to asthma management (beta-agonists are ineffective for VCD) is a key historical feature suggesting EILD 1

Diagnostic Algorithm

Step 1: Review existing spirometry for inspiratory loop flattening

• Examine flow-volume loops from symptomatic periods for truncation of the inspiratory curve 1

Step 2: Perform flexible laryngoscopy during exercise challenge

• This is the gold standard for VCD diagnosis 1, 2
• Direct observation of paradoxical vocal cord adduction during inspiration confirms the diagnosis 1
• Laryngoscopy at rest may be completely normal, so exercise provocation is essential 1, 6

Step 3: Consider bronchial provocation testing for EIB

• If VCD is confirmed but symptoms persist despite treatment, perform exercise challenge, eucapnic voluntary hyperpnea (EVH), or mannitol challenge to assess for coexisting EIB 1
• Note: Bronchial provocation results can be negative in patients with EILD who do not have bronchial hyperresponsiveness 1

Common Pitfalls to Avoid

Do not rely on history alone - timing of symptoms can vary, and both conditions can coexist 1, 4

Do not perform laryngoscopy only at rest - VCD findings are intermittent and require provocation during symptomatic periods 1, 6

Do not dismiss VCD if asthma medications fail - this is actually a key diagnostic clue for VCD rather than treatment failure 1

Screen for contributing factors: chronic postnasal drip, laryngopharyngeal reflux, and gastroesophageal reflux can trigger laryngeal hyperresponsiveness and should be treated if present 1, 2

Management Implications

Once VCD is confirmed:

• Speech therapy is the cornerstone of treatment, teaching techniques to override dysfunctional breathing patterns 2, 7
• Multidisciplinary approach including treatment of reflux, postnasal drip, or psychological factors if present 1, 2
• Corticosteroids can often be discontinued with successful VCD therapy if no true asthma coexists 2
• If both VCD and EIB are confirmed, treat each condition appropriately with speech therapy for VCD and standard asthma management for EIB 1, 4