Pediatric Annals

Special Issue Article 

Paradoxical Vocal Cord Motion in Pediatric Patients

John Palla, MD; Aaron D. Friedman, MD

Abstract

Paradoxical vocal cord motion (PVCM), also termed vocal cord dysfunction, is a poorly understood disorder of episodic dyspnea characterized by inappropriate vocal cord adduction during inspiration and potentially during expiration. It can coexist or be confused with asthma, so appropriate diagnosis is key to optimizing treatment success. Although many patients with PVCM may have underlying psychologic issues, there is emerging evidence to suggest that this entity is not psychogenic in every patient. Both laryngeal irritants and exercise have been identified as additional contributing factors in PVCM. Diagnosis of PVCM requires awake laryngoscopic confirmation. However, many patients do not exhibit signs of PVCM during this examination, despite provocation during testing. Therefore, clinical history remains key in determining which patients should proceed with behavioral therapy under the guidance of a speech pathologist. In addition, treatment may include limiting patient exposure to potential sources of laryngeal irritation. Refractory patients may benefit from psychologic assessment and treatment. [Pediatr Ann. 2016;45(5):e184–e188.]

Abstract

Paradoxical vocal cord motion (PVCM), also termed vocal cord dysfunction, is a poorly understood disorder of episodic dyspnea characterized by inappropriate vocal cord adduction during inspiration and potentially during expiration. It can coexist or be confused with asthma, so appropriate diagnosis is key to optimizing treatment success. Although many patients with PVCM may have underlying psychologic issues, there is emerging evidence to suggest that this entity is not psychogenic in every patient. Both laryngeal irritants and exercise have been identified as additional contributing factors in PVCM. Diagnosis of PVCM requires awake laryngoscopic confirmation. However, many patients do not exhibit signs of PVCM during this examination, despite provocation during testing. Therefore, clinical history remains key in determining which patients should proceed with behavioral therapy under the guidance of a speech pathologist. In addition, treatment may include limiting patient exposure to potential sources of laryngeal irritation. Refractory patients may benefit from psychologic assessment and treatment. [Pediatr Ann. 2016;45(5):e184–e188.]

During the normal respiratory cycle, the vocal cords (VCs) are widely abducted during inspiration, followed by a slight adduction during expiration.1 Paradoxical vocal cord motion (PVCM), also referred to as vocal cord dysfunction (VCD), is characterized by the inappropriate, temporary adduction of the VCs during inspiration,2,3 and some authors also include excessive VC adduction during expiration (either alone or in combination with inappropriate inspiratory adduction) in the definition.1 This leads to functional laryngeal obstruction, classically accompanied by obviously audible stridor,4,5 provided that the degree of VC adduction is significant enough to produce sufficiently turbulent airflow.

Illustrative Case

An 11-year-old boy presented to the outpatient pediatric otolaryngology (ear, nose, and throat [ENT]) clinic with new-onset breathing difficulty. He had previously been diagnosed with mild exercise-induced asthma for which he would prophylactically take an albuterol inhaler. In the week preceding his visit, he developed inspiratory breathing difficulty while at rest. This breathing difficulty spontaneously subsided after taking a nap. It then reoccurred spontaneously a few days prior to his otolaryngology visit, with intermittent resolution and recurrence. On further questioning, the patient revealed that he was anxious about running the mile at school on the day of the first episode and that, prior to his most recent episodes, he was worried about forgetting his backpack at home. Use of his albuterol inhaler did not improve his dyspnea. In between episodes, he was able to run and play football, and he denied any consistent change in voice. He also denied heartburn, throat clearing, postprandial coughing, aspiration, or choking events. There was no antecedent sickness. His past medical history was unremarkable. Testing by his pediatrician included normal chest and lateral neck radiographs.

On examination, the patient was in no acute respiratory distress but had obvious inspiratory stridor at rest that worsened with deep breathing but essentially abated when speaking. His conversational voice was minimally raspy. Lung auscultation demonstrated no wheezing, rales, or ronchi bilaterally. Awake, transnasal flexible laryngoscopy (Video) was notable for consistent near complete adduction of the membranous portions of the VCs on deep inspiration, with a posterior glottic chink (Figure 1A). During expiration and as well as inspiratory, vegetative, shallow breathing, his VCs abducted widely (Figure 1B).


            (A) Inappropriate vocal cord adduction on flexible laryngoscopy during deep inspiratory breathing, consistent with paradoxical vocal cord motion. (B) Normal vocal cord abduction during breathing in the same patient.

Figure 1.

(A) Inappropriate vocal cord adduction on flexible laryngoscopy during deep inspiratory breathing, consistent with paradoxical vocal cord motion. (B) Normal vocal cord abduction during breathing in the same patient.

The patient underwent instruction in one technique of laryngeal control therapy by the pediatric otolaryngologist (with the laryngoscope in place) with good result and was then referred to a speech pathologist for additional breathing therapy, which he ultimately did not pursue. A follow-up visit with his pediatrician 2 weeks later documented spontaneous resolution of his dyspnea.

Origins, Classification, and Epidemiology

The phenomenon of intermittent laryngeal obstruction and noisy breathing was reported as early as the mid-19th century, and was first observed laryngoscopically in 1869 by Sir Morrell Mac-Kenzie.6 In modern times, PVCM was described in 1974 by Patterson et al.7 who used the term “Munchausen stridor.” Less than a decade later, a landmark case series of women with described “vocal cord dysfunction” thought to be of psychogenic origin was published in the New England Journal of Medicine.8 Many other names have been ascribed to this entity in the medical literature, including, but not limited to, functional laryngeal obstruction, exercise-induced laryngospasm, pseudo-asthma, psychogenic stridor, and irritable larynx syndrome.4,6,9 There is a growing consensus that the term “paradoxical vocal cord (or fold) motion disorder” is a better and more specific description of the condition than “vocal cord dysfunction.”4

Numerous classification schemes for PVCM have been proposed.9–12 A recent, very practical description was advocated by Morris and Christopher,6 in which PVCM was divided into three main sources: (1) psychogenic (conversion, abuse, anxiety, stress), (2) exercise-induced, or (3) irritant-induced (reflux, allergy, laryngeal sensory neuropathy). It is notable that laryngospasm (from intubation, airway manipulation, nocturnal aspiration/reflux, and immunoglobulin E-mediated) as well as neurogenic (brainstem compression, movement disorders, multiple sclerosis) causes were excluded as sources for PVCM in this classification scheme.

Further insight into the presence of psychologic sources for PVCM was recently provided by Forrest et al.,1 who studied a population of 117 adult patients with PVCM. Notably, this was the first study to prospectively employ the most widely used personality instrument in psychology (the Minnesota Multiphasic Personality Inventory-2) to help identify the presence of psychologic pathology. As a result, they ascribed a primary (psychologic) etiology to PVCM in 75% of their cases and a secondary (nonpsychologic) cause in the remainder. Interestingly, only 33% of the patients reported a positive psychiatric history prior to this psychologic testing.

There are limited data from which to determine the overall incidence or prevalence of PVCM in either adults or children. A German study of 1,025 patients with dyspnea admitted to a rehabilitation hospital described an overall 2.8% prevalence of PVCM,13 whereas another smaller report on patients with frequent emergency department visits due to sudden-onset dyspnea found a much higher prevalence of 22%.14 Studies of patients with asthma document that between 27% and 30% also have concurrent PVCM,4,15 making it likely that patients with PVCM will be found in almost every general pediatrician's practice, although there are no prospective cohort studies to date from which to calculate prevalence.8

In the pediatric population, PVCM mainly affects adolescents, with one study noting an average age of 14.5 years.16 Additionally, almost all published reports document a greater frequency in women than in men,4,9,10,15,16 with one case series of patients younger than age 18 years reporting 82% to be girls,16 whereas other studies not exclusive to pediatric patients have found female to male ratios of 2 or 3:1.8

Clinical Course

Patients describe many different triggers for a PVCM episode. Some of the more frequent include inhaled irritants (perfumes, chemical smells), environmental changes (humidity, air temperature), physical exertion, and psychologic stress.5 However, it is possible for PVCM to occur without an obvious trigger.

The dyspnea of PVCM is hyperacute in onset (eg, seconds, not minutes) and usually of limited duration, with the acute phase lasting anywhere between 30 seconds and several minutes, although some patients may report longer durations (as in the case described in this article). Noisy breathing, throat tightness, perceived inability to breathe in (more so than expiratory difficulty), and worsening or absence of voice are typical patient symptoms that are consistent with PVCM.1,2,17 Of note, however, a study of 95 patients with PVCM found that stridor was described by only 18% of patients.15

Because PVCM is often perceived as life-threatening by the patient, the tendency is for a patient to breathe faster, which may exacerbate a Bernoulli phenomenon between the already adducted VCs during inspiration, leading to worsening or prolongation of symptoms and, in severe cases, temporary complete glottic occlusion with resultant syncope. In these instances, a patient may even sustain a head injury from a fall. After a syncopal event, the respiratory center in the brainstem will then take over and normal breathing will soon resume, without any significant risk for anoxic brain injury. It is important for medical practitioners to communicate to patients that they cannot die from isolated PVCM alone.

PVCM can also be perceived as a dangerous airway situation by physicians unfamiliar with the entity, particularly those without access to flexible laryngoscopy. Because of this, patients with PVCM have sometimes had unnecessary intubations and even tracheotomies. It is important for physicians to recognize that airway distress related to PVCM alone most often resolves with relaxation and time. Additionally, during an isolated PVCM episode, the patient will have normal pulse oximetry, chest X-ray, and blood gas levels.8,16

PVCM and Other Medical Comorbidities

Asthma and PVCM can occur simultaneously or independently, and because of the similarity of symptoms described by patients, they can be difficult to differentiate from one another. Classically, asthmatic episode onset is on the order of minutes (not seconds, as with PVCM) and occurs during the expiratory phase (versus inspiratory dyspnea of PVCM). Two key symptomatic differences often reported in asthmatic but not PVCM patients are (1) that inhalant therapies are typically helpful for asthma but not isolated PVCM, and (2) whereas patients with both disorders can experience cough during acute episodes, the cough associated with asthma tends to be productive.15,16 In cases where the diagnosis of asthma is in question after nebulous pulmonary function tests, a methacholine challenge should be considered,1 although one study has reported that methacholine caused an acute PVCM attack in two patients that could incorrectly be interpreted as asthma.18 The misdiagnosis of asthma can lead to inappropriate treatment and expense. One study from the mid-1990s found that 44% of patients who were ultimately diagnosed with isolated PVCM (and not refractory asthma, as previously thought) had been taking systemic corticosteroids for more than 4 years.15

When diagnosing PVCM, it is important to exclude any other laryngeal or central airway pathologies that might cause similar symptoms. In particular, laryngomalacia (dynamic supraglottic obstruction), tracheobronchomalacia, and excessive dynamic airway collapse (bowing of the membranous posterior central airway wall[s] into the airway lumen)19 can all present as episodic dyspnea with stridor. Static laryngotracheal narrowing from vocal cord motion impairment (usually bilateral paresis or paralysis), masses (benign or malignant), or stenosis should also be ruled out.

Most of these conditions can be relatively easily diagnosed with awake indirect flexible laryngoscopy or tracheoscopy in adults, although such testing can be more challenging in pediatric patients. Laryngospasm due to airway manipulation (eg, in the setting of intubation) or extra-esophageal reflux (either nocturnal or awake) can present similarly to PVCM, but the treatment pathways are usually different. Finally, adductor laryngeal breathing dystonia is a rare focal dystonia of the larynx during which there is constant (not episodic) inappropriate adduction of the vocal cords with resultant inspiratory stridor when the patient is awake, but the stridor disappears completely during sleep.20 Although some classify it as a form of secondary PVCM,1 it is decidedly different in duration of symptoms, and, therefore, different treatment strategies are employed (eg, laryngeal botulinum toxin injection, not speech therapy.)

Diagnostic Tests

Visualization of the VCs via awake, indirect (usually transnasal and flexible) laryngoscopy is considered the gold standard for diagnosis of PVCM. Complete VC adduction along the anterior two-thirds of the vocal folds with formation of a diamond-shaped posterior glottal chink (Figure 1A) during inspiration and sometimes persisting into expiration is classically diagnostic.6,8 On the other hand, at least one group of authors states that only inspiratory closure of the VCs of more than 50% is sufficient for diagnosis.6 Some also describe inappropriate VC adduction during expiration alone as being sufficient for diagnosis;1,15 however, one must be careful not to over-interpret normal expiratory VC adduction, which can result in 10% to 40% narrowing of the glottic aperture and continue for up to 95% of the expiratory phase.4 Furthermore, in patients with asthma and in those with other obstructive lung diseases, expiratory glottic closure can be a compensatory response for intrinsic pulmonary disease.6,15

Regardless of the nuances of laryngoscopic diagnosis, it can be difficult to diagnose PVCM if the patient is asymptomatic during the examination, even after use of inciting techniques (eg, exercise and/or inhalant triggers). In one large series, 40% of patients with a history consistent with PVCM had nondiagnostic laryngoscopies despite attempts at PVCM provocation during examination.15 Therefore, PVCM is never excluded with a “negative” laryngoscopy, and the patient's history remains crucial in helping to establish diagnosis.

In acutely symptomatic patients with PVCM, pulmonary function tests with flow-volume loops may show a flattening of the inspiratory portion, which is indicative of an extrathoracic obstruction, but this is frequently normal in the asymptomatic patient with PVCM.6 Additionally, the presence of inspiratory flattening of the flow-volume loop does not necessarily indicate PVCM, with one retrospective study finding only 36% of patients being diagnosed with PVCM after subsequent testing.21

Treatment

Treatment of a patient with PVCM requires a multidisciplinary approach. These teams can consist of pulmonologists, otolaryngologists, speech and language pathologists, and psychologists and/or psychiatrists.17

Short-term management of an acute PVCM episode starts with calm reassurance to a patient that the situation is non–life-threatening and self-limited. One of the most practical on-site maneuvers to abort a PVCM attack is panting.4 Alternatively, instructing a patient to breathe in slowly through the nose and to exhale against pursed lips or while making a soft “s” sound can be helpful (Video). Benzodiazepines have been shown to help relieve anxiety associated with episodes, and heliox (a mixture of helium and oxygen) can be temporarily helpful for episodes occurring in an acute care setting,4,8,22 but neither of these are good long-term strategies. The use of botulinum injection into the thyroarytenoid muscles has been reported in cases of refractory PVCM, but there are few data to show any long-term benefit, and its use for PVCM is now generally discouraged.5

Laryngeal control therapy (LCT) administered by a speech pathologist and/or psychologic treatments are considered the mainstay strategies for managing PVCM. The majority of children with PVCM improve with LCT.4,8,9 Maturo et al.9 found that the treatment success rate with speech therapy (ie, LCT) was high in a series of pediatric patients who presented with exercise-induced PVCM; however, it was not as successful in patients with non–exercise-induced PVCM. The authors concluded that children with PVCM symptoms at rest are best managed with synchronous psychiatric treatment and LCT, given the higher rate of underlying psychiatric conditions in that population.9

LCT is typically provided by a speech pathologist who further educates patients about PVCM and then teaches them how to control their breathing with an emphasis on throat relaxation and diaphragmatic breathing.5 Typically, 3 to 4 sessions lasting approximately 1 hour each are necessary.4 Therapy can also include laryngeal biofeedback, in which patients undergo LCT with simultaneous videolaryngoscopy, which allows them to visualize their VCs on a video monitor; this allows patients to properly “position” the VCs during inspiration and expiration.2

Psychiatric interventions for PVCM include psychotherapy, hypnosis, and patient education,17 but psychiatric medications are usually not helpful as long-term strategies.5 Psychotherapy can provide relaxation strategies, identify stressors, and aid patients in developing coping strategies. Formal psychiatric or psychologic evaluation and treatment may be added to LCT when initial efforts with LCT alone are unsuccessful.1

For those patients with secondary or irritant-induced PVCM, additional medical treatment toward reducing possible laryngeal irritants (eg, reflux, postnasal drip) should be undertaken. It is notable that in one study of pediatric PVCM patients, seven patients with suspected reflux as a contributing cause were treated with a proton pump inhibitor alone, only to have persistence of their symptoms that ultimately required LCT with or without biofeedback.9 Ultimately, patients with coexistent asthma should have their disease medically treated as well, as asthmatic episodes can trigger PVCM attacks.

Conclusion

Clinicians should be aware that patients diagnosed with asthma who appear to be refractory to medical management should be considered for the possibility of PVCM in the appropriate clinical scenario of episodic dyspnea, especially in the context of stridor and/or dysphonia. There remain several clues that physicians can use to help distinguish between PVCM and asthma: PVCM has an onset within seconds, is not responsive to abortive asthma medications, is often limited to only a few minutes in duration, and commonly presents with a nonproductive (as opposed to productive) cough. Diagnosis of PVCM is most reliably made by visualization of inappropriate VC adduction during inspiration and can be supported by inspiratory loop flattening on spirometry, but it is possible for neither of these criteria to be present if a patient is asymptomatic during examination. Therefore, clinical history remains of great importance in determining which patients might benefit from a trial of first-line treatment (LCT administered by a speech pathologist). Psychologic therapy can be helpful as an adjunct to LCT. Unrecognized PVCM can lead to unnecessary use of asthma medications, increased medical costs, and frustration among patients and medical care providers.

References

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Authors

John Palla, MD, is a Resident in Pediatrics, Comer Children's Hospital, The University of Chicago Pritzker School of Medicine. Aaron D. Friedman, MD, is a Clinical Assistant Professor, The University of Chicago Pritzker School of Medicine; and a Laryngologist and Director, Voice Center, Department of Surgery, NorthShore University HealthSystem.

Address correspondence to Aaron D. Friedman, MD, Division of Otolaryngology-Head and Neck Surgery, NorthShore University HealthSystem, 501 Skokie Boulevard, Northbrook, IL 60062; email: afriedman2@northshore.org.

Disclosure: Aaron D. Friedman is a paid consultant to the Laryngology Advisory Panel - Olympus Corporation of the Americas. The remaining author has no relevant financial relationships to disclose.

10.3928/00904481-20160331-01

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