Author and Editor Disclosure

Synonyms and related keywords: vocal cord dysfunction, VCD, paradoxical vocal cord motion, laryngeal dyskinesia, abnormal adduction of the vocal cords during the respiratory cycle, airflow obstruction, variable extrathoracic obstruction, inspiratory loop flattening, depression, obsessive-compulsive disorder, borderline personality disorder, neuroses induced by childhood sexual abuse, asthma

Background

Vocal cord dysfunction (VCD) can be characterized as an abnormal adduction of the vocal cords during the respiratory cycle (especially during the inspiratory phase) that produces airflow obstruction at the level of the larynx.

VCD frequently mimics persistent asthma and is often treated with high-dose inhaled and/or systemic corticosteroids, bronchodilators, multiple emergency department visits, hospitalizations, and in some cases, tracheostomies and intubation.

This subset of patients has problems associated with abnormal vocal cord movement without an organic basis. Flow-volume loops obtained during symptomatic periods of wheezing show a limitation of inspiratory flow suggestive of variable extrathoracic obstruction (inspiratory loop flattening). Paradoxical vocal cord motion can be confirmed on laryngoscopy performed when patients are symptomatic.

The clinical history provides limited opportunity to distinguish between patients with VCD and patients with asthma because both groups present with symptoms of wheezing, cough, and dyspnea. The localization of airflow obstruction to the laryngeal pharynx is an important clinical discriminatory feature with VCD.

Another clinical clue may be that patients with VCD often seem to have refractory asthma with poor response to beta-agonists or inhaled corticosteroids. They do not usually report nocturnal awakening due to breathlessness.

Objectively, the data reveal absence of hypoxemia in this subset as compared to compromised asthmatic persons.

The hallmark of diagnosis is noted on direct rhinolaryngoscopy; a glottic chink is present along the posterior portion of the vocal cords, while the anterior portion of the vocal cords is adducted.

Pathophysiology

During the normal respiratory cycle, the vocal cords partially abduct with inhalation and partially adduct with end-exhalation. This phasic vocal cord movement is physiologic, and it allows the unimpeded movement of air inward to the lungs and outward to the atmosphere while maintaining the alveolar patency of the lungs by providing positive airway pressure during expiration (ie, positive end-expiratory pressure [PEEP]).

The larynx therefore serves as an upper airway valve to help keep the lungs expanded. Additionally, the larynx is richly innervated, and its size is regulated by the activation of striated muscles that are under voluntary and reflexive control. Both laryngeal and respiratory motor neurons influence glottic size, as does any reflex activity arising from pulmonary and laryngeal receptors.

The mechanism that causes glottic chink narrowing or intermittent closing during inspiration independent of any changes in lower airway caliber are unknown. Nevertheless, the integrated function of the vocal cords ceases episodically, and affected patients develop acute intermittent episodes of functional airway obstruction. These clinical signs and symptoms resemble those observed in disorders such as vocal cord paralysis, asthma, epiglottitis, laryngospasm, and angioedema secondary to anaphylaxis.

Recent case reports have shown other causes of vocal cord dysfunction, such as an inlet patch of heterotopic gastric mucosa in the upper esophagus and exposure to agents such as glutaraldehyde, chlorine, or even eucalyptus.

To summarize, the exact cause of this condition is not clearly evident, but the hypothesis is that mediation of the vagus nerve may alter the laryngeal tone and lower the threshold for stimuli to produce vocal cord spasm or to precipitate the abnormal adduction of vocal cords. Recent literature suggests a greater emphasis on organic causes such as gastroesophageal reflux, laryngopharyngeal reflux, and neurologically-based dystonias.

Frequency

United States

This condition is observed in up to 10% of patients at referral centers seeking evaluation of asthma that is unresponsive to aggressive therapy. The literature reveals a high incidence of VCD in persons with psychiatric conditions (eg, depression, obsessive-compulsive disorder, borderline personality disorder, neuroses induced by childhood sexual abuse), persons with an increased body mass index and medical personnel. VCD may complicate true asthma in a small number of patients.

Mortality/Morbidity

Mortality rates are unknown, and morbidity is often significant from years of corticosteroid use, resulting in iatrogenic Cushing-like syndrome, bone density loss, and growth suppression in the pediatric population.

Sex

This condition is predominantly observed in young adult females. The authors' review of the published literature indicates a female-to-male ratio of approximately 7:3.

Age

This condition predominates in people aged 20-40 years, but it can occur in people aged 6-83 years. Recent literature suggests an increase of this condition in children and adolescents.

History

• Wheezing
• Cough
• A feeling of tightness in the throat
• Hoarseness and voice change
• Stridor
• Shortness of breath
• Dyspnea on exertion
• Inspiratory difficulty
• Sudden episodes of shortness of breath
• Unresponsiveness to bronchodilators and corticosteroids

Physical

• Laryngeal auscultation may reveal harsh stridulous sounds during symptoms.
• Wheezing may be heard in the chest (transmitted from the upper airway).

Causes

Problems associated with VCD include the following:

• Gastroesophageal reflux disease, laryngopharyngeal reflux
• Sinusitis
• Postnasal drip
• Strenuous exercise
• Occupational exposure to irritant fumes
• Environmental allergens and/or pollutants
• Psychogenic causes

Anaphylaxis
Asthma

Other Problems to be Considered

Laryngeal spasm
Foreign body obstruction
Laryngeal abnormalities (eg, neoplasm, polyp, cyst)

Lab Studies

• Laboratory studies may be indicated to exclude other diagnoses.
• • Eosinophil count
    • Eosinophilia may suggest the diagnosis of asthma if levels are greater than 5%, but absence of this sign does not clearly exclude the diagnosis, especially if the patient has been frequently treated with oral corticosteroids.
    • Elevated eosinophil counts may also be observed in skin diseases such as atopic dermatitis and in clinical entities such as pulmonary infiltrates with eosinophilia, allergic bronchopulmonary aspergillosis (ABPA), Churg-Strauss syndrome, and parasitic diseases.
    • VCD, per se, is not associated with an elevated blood eosinophil count.
  • Serum immunoglobulin E (IgE) assay
    • Elevated serum IgE is observed in allergic individuals, but it is not specific for asthma.
    • This elevation may be observed in other syndromes such as ABPA and Churg-Strauss syndrome. Its presence may indicate a concomitant diagnosis of asthma even though its absence is not exclusionary.
    • VCD, per se, is not associated with an elevated serum IgE level.
  • Arterial blood gases (ABG): ABG findings reveal an alveolar-arterial gradient (ie, the alveolar-arterial oxygen difference), which is a measure of oxygen delivery from the lungs to blood, that is usually within reference ranges in the subset of patients with VCD. In patients with acute asthma, ABG findings may be abnormal, indicative of hypoxemia.

Imaging Studies

• Chest radiography
• • Radiographic findings are usually normal, or radiographs may show hyperinflation in asthmatic individuals.
  • Chest radiography may be used to evaluate other pulmonary diseases or structural laryngeal and cardiac abnormalities that may explain or support the patient's respiratory symptoms.

Other Tests

• Pulmonary function test
• • Spirometric testing supports the diagnosis of VCD in symptomatic individuals. This study is used to identify individuals with asthma or other pulmonary abnormalities, including upper airway obstruction. In patients without coexisting asthma, spirometric findings are usually within the reference range during an episode. If flows are decreased during an episode, forced vital capacity FVC) decreases in tandem with forced expiratory volume in the first second (FEV₁), which is not consistent with classic airflow limitation.
  • Flow-volume loops are the most useful tool in discriminating between VCD and asthma. Flow-volume loops typically demonstrate inspiratory loop flattening, ie, an inspiratory flow decrease during symptomatic periods suggestive of VCD (see Image 1). In addition, during VCD symptoms, an abrupt drop and rise in the expiratory flow volume loop may be observed in the absence of coughing.
  • Results of routine measurement of airflow obstruction (ie, FEV₁, peak expiratory flow rate) can be within reference ranges in VCD if the vocal cords close only on inspiration. If vocal cord closure occurs during both inspiration and expiration, FEV₁ can decrease along with the decrease in FVC, making the FEV₁/FVC ratio within the reference range. This distinguishes isolated VCD from VCD concomitant with asthma, in which the FEV₁ is proportionately decreased more than the FVC, representing airflow limitation.
• Methacholine provocation
• • A patient with VCD shows no bronchial hyperresponsiveness on methacholine challenge unless he or she has concomitant asthma.
  • This challenge is therefore most helpful in excluding the diagnosis of asthma. It may also be helpful in confirming that a patient with VCD has coexisting asthma.

Procedures

• Laryngoscopy
• • The criterion standard for the diagnosis of VCD is direct visualization of the paradoxical adduction of the true vocal cords during inspiration.
  • The classic textbook picture is the adduction of the anterior two thirds of the vocal cords with a posterior diamond-shaped chink through which air flows during the inspiratory phase (see Image 2).

Medical Care

A multidisciplinary approach with a physician and speech therapist and a psychiatrist, if needed, is usually effective.

• Speech therapy
• • The mainstays of treatment for VCD involve teaching the patient vocal cord relaxation techniques and breathing exercises. These procedures have been very successful and are used concomitantly with psychological support in difficult cases.
  • The role of the speech therapist is to effectively teach and communicate a comprehensive speech therapy plan with appropriate breathing exercises.
• Psychotherapy: The role of the psychiatrist is to implement cognitive behavior psychotherapy or general psychotherapy based upon evaluation of psychiatric and/or personality disorders.
• Helium-oxygen therapy
• • This therapy consists of administration of a helium-oxygen mixture (heliox), which is less dense than air and thus reduces the turbulence in the airway during inspiration.
  • Heliox administration provides only a short-term benefit, but it may be very helpful in the emergent treatment of acute VCD.
• Botulinum toxin
• • An intralaryngeal injection of botulinum toxin relieves symptoms by blocking acetylcholine release at the motor end plate and creating a laryngeal muscle weakness, thus facilitating inspiratory and expiratory airflow.
  • Its use is considered experimental, and equivocal reports in the literature illustrate both effectiveness and lack of benefit.
• Panting: This maneuver causes the adducted vocal cords to relax, which increases the glottic aperture.
• Topical lidocaine
• • This may be applied to the larynx.
  • The mechanism of action is to break the cycle of hyperactive glottal and supraglottal muscle contractions.

Consultations

• Otolaryngologist
• Pulmonologist
• Allergist and/or immunologist
• Speech therapist
• Psychiatrist

Diet

No diet restrictions are necessary.

MEDICATION

No specific pharmacotherapy is indicated.

FOLLOW-UP

Further Outpatient Care

• Patients must receive further care to determine the response to patient education and speech therapy and to assess the need for referral for psychiatric care.

Deterrence/Prevention

• Deterrence and prevention can be achieved by adherence to speech therapy guidelines and exercises and by relaxation therapy or other measures to decrease anxiety.

Prognosis

• Prognosis is good with effective response to speech therapy, which allows patients to take control of their disorder.

Patient Education

• Patient education ideally uses a multidisciplinary approach with involvement of a physician and speech therapist and, if needed, a psychiatrist.
• The physician's role is to inform the patient of test findings, especially the absence of diseases such as asthma, and to explain the nature of the condition. Patients often express a positive reaction to the initial explanation, and such a reaction usually implies a good prognosis.
• Online patient educational sources
• • VCD Information from the National Jewish Medical and Research Center
  • Center for Voice Disorders of Wake Forest University
  • Johns Hopkins
  • VCD: Paradoxical Vocal Cord Motion - A Thorough Review
  • American Academy of Allergy, Asthma and Immunology

MISCELLANEOUS

Medical/Legal Pitfalls

• Failure to recognize coexisting asthma or to recall that VCD is a diagnosis of exclusion
• Failure to recognize functional causes of upper airway obstruction (eg, other pulmonary, cardiac, and structural laryngeal abnormalities) that must be excluded because they may be the etiology of the patient's respiratory symptoms
• Failure to recognize the following organic causes or associated problems, which must be excluded:
• • Brain stem compression
  • Upper and/or lower motor neuron injury
  • Gastroesophageal reflux
  • Asthma
  • Foreign body obstruction
  • Anaphylaxis

Special Concerns

• Early diagnosis of VCD prevents adverse effects of unnecessary and ineffective antiasthmatic therapy (especially corticosteroids).
• Larger population trials are needed to further delineate the true incidence of VCD that is mistaken for asthma because the data in the authors' review indicate that VCD is more common than previously perceived.