Paradoxical Vocal Fold Movement Disorder (PVFMD) is a cause of dyspnea that can mimic or occur alongside asthma or other pulmonary disease. Treatment with Laryngeal Control Therapy is very effective once the entity is properly diagnosed and contributing comorbidities are managed appropriately. In understanding the etiology of PVFMD, focus has broadened beyond psychiatric factors alone to include the spectrum of laryngeal irritants (laryngopharyngeal reflux, allergic and sinus disease, sicca, and possibly obstructive sleep apnea). The following is a discussion of the history, terminology, epidemiology, diagnosis, comorbid conditions, and treatment of this entity.
Key points
- •
Paradoxic vocal fold movement disorder is more common than previously recognized and should be considered when dyspnea is present without pulmonary disease or out of proportion to the degree of coexistent pulmonary disease.
- •
Laryngeal control therapy (also called respiratory retraining therapy) with a speech language pathologist is the cornerstone of treatment of paradoxic vocal fold movement disorder.
- •
Flexible laryngoscopy must be performed to diagnose paradoxic vocal fold movement disorder. Laryngeal control therapy techniques should be trialed during this initial scope.
- •
Bilateral vocal fold paralysis, subglottic stenosis and tracheal stenosis must be ruled out, particularly when stridor is present.
- •
Comorbidities, such as laryngopharyngeal reflux, sinus or allergy problems, laryngeal sicca, and obstructive sleep apnea, should be identified and treated.
- •
Attention to controlling anxiety and stress levels is important. However, the role for counseling or psychiatric care in treating paradoxic vocal fold movement disorder may be decreasing as the contribution of medical comorbidities becomes more widely recognized.
| COPD | Chronic obstructive pulmonary disease |
| ILS | Irritable larynx syndrome |
| LCT | Laryngeal control therapy |
| LPR | Laryngopharyngeal reflux disease |
| OSA | Obstructive sleep apnea |
| PFT | Pulmonary function testing |
| PVFMD | Paradoxic vocal fold movement disorder |
| SLP | Speech language pathologist |
Introduction
The first hint of paradoxic vocal fold movement disorder (PVFMD) in the medical literature came in 1842, in which a patient with “hysteric croup” was described. The paradoxic movement itself was first visualized via laryngoscopy in 1869 by Mackenzie, who visualized glottic closure in direct correlation with the patient’s stridor. In current-day practice, patients with much lesser degrees of stridor and vocal fold narrowing are often evaluated, thanks in great part to the increasing recognition of this disorder by the greater medical community. However, there are clearly still gaps in recognition and understanding of PVFMD.
Introduction
The first hint of paradoxic vocal fold movement disorder (PVFMD) in the medical literature came in 1842, in which a patient with “hysteric croup” was described. The paradoxic movement itself was first visualized via laryngoscopy in 1869 by Mackenzie, who visualized glottic closure in direct correlation with the patient’s stridor. In current-day practice, patients with much lesser degrees of stridor and vocal fold narrowing are often evaluated, thanks in great part to the increasing recognition of this disorder by the greater medical community. However, there are clearly still gaps in recognition and understanding of PVFMD.
Nature of the problem
PVFMD is a disorder in which someone with otherwise normal vocal fold motion suffers from intermittent constriction of the vocal folds during respiration, causing dyspnea and the sensation of throat tightness. The presentation often mimics asthma, although it can occur alongside asthma or other pulmonary disease. The cause of PVFMD was thought to be only psychologic for many years, with stress and anxiety as the primary triggers; the current clinical picture is evolving and may be influenced more by medical comorbidities than previously recognized. Husein and colleagues established in 2008 that 70% of their patients with PVFMD had a psychological profile matching, at least in part, that of a conversion disorder. However, 50% of their patients had comorbid conditions such as gastroesophageal reflux disease or asthma, and they were more likely to have these medical conditions than they were to have a psychiatric history.
Stress and anxiety are still recognized as significant triggers for many patients, but anything that irritates the vocal folds can make paradoxic movement more likely. There is a well-established link to laryngopharyngeal reflux (LPR), although evidence on whether its treatment leads to resolution of PVFMD is contradictory. Laryngeal edema (associated with reflux complaints in 90%) was found in 72% of patients diagnosed with PVFMD in a recent prospective study. This reflux and edema can trigger mild PVFMD in some and full-blown laryngospasm in others.
Other factors that lead to laryngeal mucosal irritation, such as tobacco abuse, allergic laryngitis, viral illness, and untreated sleep apnea, may trigger episodes of PVFMD and make it more difficult to treat. Rhinosinusitis and the resulting postnasal drip can directly cause irritation of the vocal folds; however, inflammation may also result indirectly from the release of inflammatory mediators, as described in the “One Airway” theory. Other respiratory tract irritants such as inhaled chemicals, smoke, or gases have long been recognized as prominent triggers in PVFMD as well. Understanding of the irritable larynx syndrome (ILS), as described by Morrison and colleagues in 1999, is crucial to a full understanding of PVFMD. PVFMD may, in fact, represent a subset of ILS in many cases.
At the more severe end of this spectrum of vocal fold irritability is laryngeal sensory neuropathy, in which a generalized laryngeal hyperresponsiveness develops after an initial inflammatory insult (such as a viral illness, trauma, or surgery in the neck). Even after controlling for factors such as reflux or allergic inflammation, the patient remains hypersensitive; chronic cough is often present as well. The overlap between PVFMD and laryngeal sensory neuropathy should be recognized, particularly when someone is not responding well to laryngeal control therapy (LCT) alone.
Distinction between PVFMD and the spectrum of vocal cord paresis, paralysis, or synkinesis is crucial. Patients with PVFMD do not have any deficit in vocal fold mobility; full abduction must be seen at some point during the examination to differentiate it from bilateral vocal fold paralysis or paresis. Failure to do so could lead to respiratory embarrassment. Another crucial responsibility of the otolaryngologist, particularly when stridor is present, is ruling out subglottic or tracheal stenosis as the cause of dyspnea.
Terminology
The nomenclature associated with PVFMD is confusing; it is also generally unimportant. A shift away from the term “Vocal Cord Dysfunction” has occurred primarily because of confusion with pathologic abnormalities causing dysphonia rather than dyspnea. Laryngologists may receive referrals for “vocal cord dysfunction” when a patient has a lesion of the vocal fold or a vocal fold paralysis, a very different entity from “Vocal Cord Dysfunction,” in which there is typically no dysphonia and necessarily no impairment of nerve function or vocal fold mobility. (It should be noted that some authors would disagree that dysphonia is not part of the clinical picture of PVFMD. )
There is some argument that because a small amount of adduction normally occurs with expiration, the term “paradoxic” is not appropriate when constriction is limited to expiration. However, it would be argued that a constriction greater than 50% on either inspiration or expiration is not normal and is paradoxic to the open airway configuration needed for comfortable respiration.
Epidemiology
PVFMD is likely widely underdiagnosed, particularly in rural primary care settings in which asthma not responding to typical treatments is simply assumed to be poorly-controlled. A study of 52 school-age children with suspected poorly controlled asthma found that only 15% actually met criteria for asthma, but 27% were found to have PVFMD. PVFMD has been found to be present at rates of up to 40% among patients with refractory or exercise-induced dyspnea. Studies focusing specifically on elite athletes and military personnel have been carried out, making it clear that these populations are very much prone to PVFMD as well. Another study showed that 20% of female patients undergoing flexible laryngoscopy for any reason were found to have some degree of PVFMD.
There is also the question of whether PVFMD is actually overdiagnosed in some centers. As practitioners in a high-volume laryngology practice often referred to as the “VCD Clinic” within our medical center, we have raised this question ourselves. We now receive referrals for PVFMD evaluations on patients with significant underlying pulmonary disease, such as moderate to severe chronic obstructive pulmonary disease (COPD), but with dyspnea out of proportion to the results of their pulmonary testing. We at first questioned the utility of testing in these patients; glottic constriction on exhalation has been shown in multiple studies to be part of the clinical picture of obstructive pulmonary disease. However, we are finding that if we see clear improvement of vocal fold abduction with use of the breathing techniques, LCT can help some of these patients decrease the frequency or severity of their dyspnea and medication use. Studies are desperately needed on efficacy of therapy in this group and are underway at the author’s institution.
Undiagnosed PVFMD has been shown to lead to immense health care costs. There are multiple reports of unnecessary intubations and even tracheostomies performed in cases of undiagnosed PVFMD. A retrospective case-control study showed that, before their diagnosis, patients with PVFMD had higher utilization of health care than those with moderate persistent asthma. Research is currently underway at the author’s institution to study whether asthma medication use decreases after the diagnosis of PVFMD is made.
Diagnosis and clinical findings: history
There are several symptoms and elements of the history that are characteristic of PVFMD ( Box 1 ). These elements include a feeling of tightness in the neck or throat, more difficulty getting air in than out, inconsistent or failed response to inhalers, and symptoms that are precipitated by anxiety, strong emotion, odors, changes in humidity or temperature, and exposure to chemicals. Dyspnea tends to come on more quickly with PVFMD than with asthma. It also tends to resolve more quickly with rest, rather than becoming most severe after cessation of activity, as in exercise-induced bronchoconstriction. In elite athletes particularly, the dyspnea may be provoked only by high-intensity exercise rather than with long, lower-intensity workouts. Patients will often note “wheezing,” but on detailed questioning actually describe noisy breathing more on inspiration than expiration. A choking sensation has been found to be more predictive of PVFMD than of exercise-induced bronchoconstriction. It is not uncommon for patients to have breathing “tricks” that they have tried on their own before presentation, often with some success.
Tightness in neck rather than chest
More difficulty getting air in than out
Symptoms brought on by exertion
Events associated with stress or strong emotions
Events triggered by strong odors, perfumes, or chemicals
Rapid onset of dyspnea
Noisy breathing (usually on inhalation)
Poor or inconsistent response to inhalers
History of negative asthma workup
In patients who ultimately are diagnosed with both asthma and PVFMD, there is often a distinction between episodes of dyspnea provoked by asthma and those related to PVFMD. Keeping in mind how commonly the two exist together, it is important not to discount the possibility of PVFMD when the patient reports some episodes that respond quickly to albuterol use. These same patients, on detailed questioning, will often say that they can tell the difference between the two even before they unsuccessfully try their inhaler.
Diagnosis and clinical findings: physical examination
Physical examination findings, apart from those found on laryngoscopy ( Box 2 ), are nonspecific in PVFMD. The absence of a true end-expiratory wheeze supports the diagnosis, as does the presence of stridor loudest at the neck in the absence of subglottic or tracheal stenosis.
Laryngoscopic findings that support PVFMD
- •
Severe vocal cord constriction during respiration that corresponds temporally to audible stridor
- •
Posterior glottic chink during respiration (severe vocal cord adduction with only a small opening posteriorly)
- •
Greater than 50% narrowing of the glottis occurring at least twice following each of these tasks: breath-holding, counting out loud to 10 on one breath, counting out loud as high as possible during one breath, sustaining an “ee” as long as possible on one breath
- •
Narrowing of the glottis of greater than 50% occurring during “easy breathing”
- •
Increased narrowing of the glottis after presentation of strong odors or exertion
- •
Improvement in vocal fold abduction with use of LCT techniques
Laryngoscopic findings that do not support PVFMD
- •
Audible stridor heard during full vocal fold abduction
- •
Constant narrowing on exhalation that worsens with LCT techniques (often seen in COPD patients)
- •
Failure to fully abduct vocal folds at any point during examination (could indicate a bilateral vocal fold paresis or paralysis)
Diagnosis and clinical findings: diagnostic modalities
Diagnosis of PVFMD requires a flexible laryngoscopic examination, during which the movement of the vocal folds is observed during quiet breathing, after provocative techniques, and again after performance of laryngeal control techniques. This flexible laryngoscopic examination must be performed to confirm the presence of PVFMD, as well as to assess which breathing techniques are most beneficial. It is also absolutely crucial in ruling out actual paralysis, in addition to excluding other pathologic abnormality. The rate of coexistent laryngeal lesions in PVFMD patients has been shown to be as high as 33%. Subglottic or tracheal stenosis must also be ruled out. In patients with marked stridor or risk factors for stenosis, lidocaine is often dripped onto the vocal folds and office tracheobronchoscopy performed at the time of their initial evaluation, if imaging of the trachea has not been previously obtained.
Topical decongestant and lidocaine are applied to the nasal cavity before the examination, because it has been shown not to affect vocal fold movement and prevents some of the false positives resulting from poor scope tolerance. Vocal fold movement during respiration in patients without PVFMD typically shows wide abduction with inspiration and slight narrowing with exhalation. Patients with PVFMD show narrowing on inspiration and/or a more marked narrowing on exhalation. The latter is more often seen when the patient is not acutely symptomatic. In some cases the patient will suspend breathing between inhalation and exhalation, with a narrowed glottis. In severe cases of inspiratory narrowing, the “posterior glottic chink” described by Christopher and colleagues in 1983 is seen. Most patients with PVFMD will demonstrate a degree of narrowing even at rest, particularly following the provocative exercises (breath-holding with strong Valsalva, counting out loud as long as possible on a single breath). If they do not, various strong odors are presented during the laryngoscopic examination (choosing those that are most bothersome to the patient) or the patient is taken to an exertion room where they run on a treadmill as their heart rate and oxygen saturation are monitored. The flexible laryngoscopy is then repeated immediately after the patient reaches the point of feeling dyspneic ( Box 3 ). It is rare to get absolutely no narrowing after provocative exercises and attempts to replicate the patient’s particular triggers. However, in certain high-risk groups such as young athletes or adults with absolutely no comorbid pulmonary disease, the diagnosis is still suspected even after laryngoscopy does not demonstrate narrowing. It is one of the challenges of diagnosing this disorder that the situation or sport that induces the problem (ie, skiing or swimming) cannot always be replicated. In this setting, a trial of LCT is performed and the flexible laryngoscopy is repeated during therapy (particularly if biofeedback is used as a therapeutic technique) to see if this represents a sampling error. If the patient thinks the breathing techniques are helping him or her, a full course of therapy is continued.
