Vocal Cord Dysfunction (VCD) is a respiratory condition often presenting as a breathing crisis, leading many to initially suspect asthma. It involves a temporary, involuntary malfunction of the upper airway, distinct from the lower airway inflammation seen in asthma. Because its symptoms closely mirror those of a common lung disease, VCD is frequently misdiagnosed. This misdiagnosis makes it difficult to determine how common the condition is in the general population and presents a significant challenge when gathering accurate statistics.
Understanding Vocal Cord Dysfunction
VCD, also known as paradoxical vocal fold movement, is defined by the inappropriate closure of the vocal cords. Normally, these two folds of muscle tissue in the voice box (larynx) open wide during inhalation to allow air into the lungs. During a VCD episode, the vocal cords paradoxically adduct, moving toward the center and partially closing the airway, particularly during inhalation. This laryngeal adduction restricts airflow, creating a sensation of suffocation or difficulty breathing. This mechanism distinguishes VCD as an upper airway obstruction problem, unlike asthma, which involves the narrowing of the bronchial tubes in the lower lungs.
The Current Data on VCD Prevalence
The true prevalence of VCD in the general population remains largely unknown, primarily because of its episodic nature and the high rate of misdiagnosis as refractory asthma. Since there is no mandatory reporting system, researchers rely on studies of specific patient groups, which show a wide range of estimates. These studies consistently indicate that VCD is far more common among patients experiencing chronic breathing difficulties that do not respond to standard asthma therapy.
Among patients referred to specialized clinics for difficult-to-treat asthma, the prevalence of VCD is estimated to be between 4% and 10%. In populations with frequent emergency room visits for sudden dyspnea, VCD prevalence has been reported to be as high as 22%. VCD is also disproportionately observed in certain cohorts, including competitive athletes, where it is often termed Exercise-induced Laryngeal Obstruction (EILO). Up to 14% of children and adolescents hospitalized with an asthma diagnosis were found to have VCD.
Differentiating VCD Symptoms from Asthma
A careful review of symptoms can often distinguish VCD from asthma, which is important since VCD does not respond to typical asthma medications. A VCD episode often involves difficulty breathing in, which can produce a high-pitched sound called stridor, originating from the throat. In contrast, asthma typically causes more difficulty breathing out, resulting in a wheeze heard in the chest.
Individuals with VCD frequently localize the sensation of tightness or restriction to the throat or neck area. Asthma sufferers more commonly report tightness centered in the middle or lower chest. VCD attacks typically have a rapid onset and resolve spontaneously within a few minutes, while asthma exacerbations tend to build up and take longer to subside. The most telling clinical difference is the lack of improvement after using an inhaled bronchodilator, the standard treatment for asthma.
Primary Causes and Common Triggers
The development of VCD is often complex, stemming from underlying medical conditions that irritate the laryngeal area. Laryngopharyngeal Reflux (LPR) or Gastroesophageal Reflux Disease (GERD) is a primary cause, as the backflow of stomach acid irritates the vocal cords and makes them hypersensitive. Other irritants contributing to the condition include chronic post-nasal drip from conditions like rhinosinusitis and recent upper respiratory tract infections.
A variety of environmental and physical factors can also trigger an acute VCD episode. Intense physical exertion is a well-known trigger, particularly in athletes. Inhaled irritants such as strong odors, perfumes, smoke, and fumes can cause the hyper-reactive vocal cords to clamp shut. Significant emotional stress, panic, or anxiety are also common triggers, causing the vocal cord muscles to tense and contract inappropriately.
Treatment Approaches for VCD
Treatment for VCD is primarily non-pharmacological, focusing on behavioral and breathing retraining strategies to regain conscious control over the laryngeal muscles. Speech-Language Pathologists (SLPs) typically provide this intervention, which is highly successful in managing the condition. Patients are taught techniques like “relaxed-throat breathing” and lower-abdominal breathing exercises to consciously open the vocal cords during an episode.
One rescue technique involves a quick, focused exhalation followed by short, shallow inhalations, sometimes called the “sniff-pant” technique, which helps break the paradoxical adduction. Treatment also includes identifying and managing the underlying medical conditions that contribute to VCD. This involves treating conditions like GERD with medication or dietary changes and addressing psychological triggers with counseling or psychotherapy when anxiety or stress is a factor.