Vocal Cord Dysfunction (VCD), known medically as Paradoxical Vocal Fold Movement (PVFM), is a respiratory condition that often presents as severe breathing difficulty. The disorder involves the voice box, or larynx, and the vocal folds or cords inside it. VCD is a functional disorder of the upper airway that is frequently misdiagnosed as asthma due to the similarity of symptoms. This misdiagnosis often leads to ineffective treatment with standard asthma medications.
Understanding Vocal Cord Dysfunction
The core mechanism of VCD involves an abnormal, or paradoxical, movement of the vocal cords during the breathing cycle. Normally, when a person inhales, the vocal cords move apart, or abduct, creating a wide opening for air to flow into the lungs. During an episode of VCD, the vocal cords mistakenly move toward each other, or adduct, instead of opening. This inappropriate closure creates a partial obstruction at the level of the larynx, which limits the amount of air entering the windpipe. The resulting narrowing of the upper airway causes the sensation of struggling to breathe. This response is thought to be a form of laryngeal hyperresponsiveness, where the protective reflex of the airway becomes overactive. This hypersensitivity can be triggered by a variety of irritants, including acid reflux, upper respiratory infections, strong odors, psychological stress, and exercise.
Common Symptoms and Presentation
Episodes of VCD are typically sudden in onset and can resolve just as quickly, often lasting only a few minutes. The most common complaint is shortness of breath, which is often described as a feeling of choking or suffocation. Individuals frequently report a sensation of tightness in the throat or neck, rather than the chest pain associated with lower airway issues. A characteristic sign of VCD is noisy breathing upon inhalation, known as inspiratory stridor. Voice changes may also occur during or immediately after an episode, such as hoarseness, a strained voice, or a temporary inability to speak (aphonia). Patients may also experience a persistent cough or the need to frequently clear their throat.
Distinguishing VCD from Asthma
VCD is often mistaken for asthma because both conditions involve intermittent breathing difficulty, wheezing, and coughing. A primary clinical difference lies in the phase of breathing that is most affected. VCD primarily impacts inhalation, while asthma mainly restricts exhalation. The noise associated with VCD is typically inspiratory stridor, whereas asthma is characterized by an expiratory wheeze, a whistling sound on breathing out.
The location of the obstruction is another fundamental distinction. VCD is an upper airway problem at the larynx, and asthma affects the lower airways, specifically the bronchioles. This difference explains why VCD symptoms do not typically respond to standard bronchodilator medications used for asthma. Furthermore, oxygen saturation levels in the blood usually remain normal during a VCD episode, even when the person feels severely distressed.
Diagnosis and Management Strategies
Diagnosis of VCD is challenging because the symptoms are episodic, meaning the patient may be asymptomatic during a routine examination. The gold standard for definitive diagnosis is direct visualization of the vocal cords using a fiberoptic scope, called a laryngoscopy, while the patient is symptomatic. When symptoms are not present, specialized tests may be used to provoke an episode, such as Continuous Laryngoscopy Exercise Testing (CLET) or a methacholine challenge. Pulmonary function testing with a flow-volume loop can also provide supporting evidence by displaying a characteristic flattening on the inspiratory curve, which indicates an obstruction in the upper airway.
The primary management for VCD involves behavioral and therapeutic interventions rather than medication. Speech-language pathology (SLP) is a cornerstone of treatment, focusing on laryngeal-respiratory retraining therapy. Therapists teach specific breathing techniques, such as quick-release maneuvers and pursed-lip breathing, to help consciously override the vocal cord spasm and interrupt the cycle.
Long-Term Management
Long-term strategies also include identifying and managing underlying triggers. This involves treating gastroesophageal reflux disease (GERD) or addressing psychological factors like anxiety and stress. Education about the condition’s mechanism and practicing breathing exercises outside of an attack are important components. For acute, severe episodes, techniques like panting or the use of a helium and oxygen mixture (heliox) may be used to reduce airway resistance and provide immediate relief.