Approach
The lack of appreciation and awareness of paradoxical vocal fold motion (intermittent laryngeal obstruction) (PVFM/ILO) among primary care physicians and/or specialty physicians, including gastroenterologists, may be due to a lack of specific investigations for the disorder and confusion over the many different terms used to identify it. Consequently, the physician may overlook PVFM/ILO, contributing to a delay in its diagnosis and treatment.[65]
Diagnosis relies on clinical history, pulmonary function tests(PFTs), and laryngeal visualization.[31][66] The clinical manifestations of PVFM/ILO represent a continuum from chronic throat clearing and chronic cough to PVFM/ILO and laryngospasm, each reflecting varying degrees of hyperfunctional airway protection.
A simple clinical pathway can be followed when a patient presents with concerns of undiagnosed breathing attacks or breathing attacks that have not responded to treatment.[67] Once other airway disease has been diagnosed and treated, persistence of unmanaged breathing attacks should be referred to a specialized otolaryngologist and speech language pathologist.
As PVFM/ILO attacks cause fear in the patient and those around them, the patient needs to have confidence in the team, which in turn must be sure of its ability to give an accurate diagnosis. This combination will decrease unnecessary pharmacologic intervention and emergency-department attendance.
Presenting features
The most common clinical presentation of PVFM/ILO is the description of an acute breathing attack, specifically with tightness in the throat and difficulty inhaling deeply, with subsequent air hunger.
Attacks occur episodically, in response to specific triggers, and are not characterized by chronic breathing difficulty or chronic shortness of breath.
Symptoms show characteristic rapidity of onset and resolution. Breathing difficulty occurs in response to a trigger and resolves with the elimination of that trigger.
Triggers may include exercise, sitting, eating, sleeping, airborne irritants (e.g., smoke, perfume, chemical odors), extreme temperatures, and stress.[3][58]
Patients may report a PVFM/ILO response to airborne irritants that were not triggers prior to the initial PVFM/ILO event.[58]
Patients who have been previously diagnosed with or treated for asthma tend to report no benefit from inhaled bronchodilators or corticosteroids.
Chronic cough and PVFM/ILO share similar attributes, although increased age and symptoms of laryngopharyngeal reflux (LPR) are more likely to result in chronic cough.[68] Cough has been reported to be associated with PVFM/ILO in up to 59% of cases.[1] In addition to asthma and postnasal drip, cough can be related to distal and proximal acid exposure, upper-airway microaspiration, and dysphagia.[57] Cough is considered to be on the continuum of vocal fold adductor behavior in response to sensory stimuli.
Other common symptoms of PVFM/ILO include inspiratory stridor, inspiratory and biphasic wheeze, dysphonia, and episodic dyspnea. There may also be symptoms of voice changes.[39][69] Loss of consciousness is an uncommon but severe symptom. It may be due to a number of reasons including hyperventilation or anxiety.
Palpable laryngeal tension (laryngeal elevation, pain and/or tenderness around the larynx, and narrowing of the thyroid hyoid space) is a common clinical examination finding.[35][70]
Past medical history and risk factors
Several medical conditions and activities have been identified as risk factors for the development of PVFM/ILO.[66] Thus, all patients with suspected PVFM/ILO should be assessed for a history of the following:[56]
LPR - Reflux Symptom Index (RSI) score >13 indicates a correlation with LPR (a self-administered 9-question symptom score; 0-45 points)
GERD
Asthma
Upper respiratory infection
Anxiety and stress (emotional and physical)
Competitive athletics
Muscle tension dysphonia
Adductor laryngeal breathing dystonia
Recent surgery with intubation
Exclusion of related conditions
When an individual presents to the primary care physician with reports of chronic cough and/or breathing attacks, a simple clinical pathway can be followed.[67]
PVFM/ILO can be considered a diagnosis of exclusion once other causes of chronic cough and breathing attacks have been ruled out:[71]
Reactive airway disease: PVFM/ILO has been frequently mistaken for asthma, which has led to unnecessary medical intervention ranging from pharmacology to hospitalization
Other pulmonary disease
Other laryngeal disease or obstruction
Cardiac disease
GERD
Neurologic disease
Prior to otolaryngology/speech pathology evaluation and treatment, the patient should be referred for:[20][28][29][30][58]
Asthma evaluation and treatment: vocal cord dysfunction and asthma can coexist in up to 50% of individuals in some studies. Thus, diagnosis and management of asthma by a specialist is important to begin differentiation of breathing attacks. Prior to PVFM/ILO diagnosis, patients with breathing attacks are often treated for asthma for several years with bronchodilators and corticosteroids.
Cardiac evaluation and treatment: ECG and stress testing may be indicated for patients suspected of having cardiac-related breathing problems. A change of medicine should be considered for patients with chronic cough who are taking ACE inhibitors.
Chest x-ray: patients with PVFM/ILO and no related conditions will have normal chest imaging.
Once other airway disease has been diagnosed and treated, persistence of unmanaged breathing attacks should be referred to a specialized otolaryngologist and speech language pathologist.
Case history form
Patients complete a case history form to guide the clinician's investigation into the nature of the breathing attacks, triggers, medical history, and, most importantly, patient awareness. The Dysphonia Index has been developed as a patient self-identification measure to assess upper airway symptoms. This can be included in the case history form and can also be used to evaluate treatment outcomes.[72][73]
Some patients will be able to differentiate asthma clearly from other breathing attacks, identify the onset of the problem, and specify triggers. Others will simply relay that they have trouble breathing or a cough.
The clinical investigator will have to address several issues to help the discovery and learning process. Both adolescents and adults should be asked about:
Their daily schedule
Attitudes toward achievement
How much the breathing attacks interfere with daily living or specific goals
Stress and emotional problems can be factors linked to increased LPR and PVFM/ILO so it is important to ask the patient about stressors and any complex professional or personal situations.
Laryngeal imaging
Flexible nasolaryngoscopy is performed by an experienced speech language pathologist or specialized otolaryngologist and is the primary investigation for all patients suspected of having PVFM/ILO.[20][31][39][74][75] It allows:[39][76]
Full visualization of the larynx during resting breathing, talking, and swallowing[Figure caption and citation for the preceding image starts]: Normal larynx: normal color of vocal folds and surrounding structures, smooth vocal fold edgesFrom the collection of the University of Wisconsin School of Medicine and Public Health [Citation ends].
Visualization of the larynx while the patient reproduces the breathing attack and/or noisy breathing during continuous exercise or exposure to trigger irritants.[Figure caption and citation for the preceding image starts]: Reproduction of breathing attack: adduction of arytenoid complex during inhalationFrom the collection of the University of Wisconsin School of Medicine and Public Health [Citation ends].
Identification of adduction during inspiration or early expiration during an asymptomatic state, during symptoms or with a provocative study to support a diagnosis of PVFM/ILO.
Exclusion of other etiologies, including upper-airway obstruction, space-occupying lesions, laryngomalacia, laryngeal tremor, vocal fold paresis/paralysis, and postintubation phonatory insufficiency.
It may be possible to have an asymptomatic larynx and still meet criteria for diagnosis of PFVM/ILO.[75][77]
Pulmonary function tests/flow-volume plot
PFTs and flow-volume plots are recommended for all patients with suspected PVFM/ILO in order to establish flow volume loops, which may support or rule out the presence of PVFM/ILO. These tests can be performed before or after ENT and a speech language pathologist's assessment.
PFTs reveal a normal total lung capacity.
Spirometry can help to differentiate between restrictive and obstructive airway disorders and may reveal comorbid asthma or other obstructive or restrictive lung pathology.
Flow-volume plot shows a truncated inspiratory loop.[75]
Patients with PVFM/ILO may have low forced vital capacity, low forced inspiratory vital capacity, and low forced inspiratory volume at 0.5 seconds of the inspiratory phase.[78]
Spirometry will yield diagnostic results, but the patient may require more advanced assessment with exercise bronchoprovocation in the pulmonary laboratory.
Sinus CT
CT imaging of the sinuses shows minimum or absence of sinus inflammation in PVFM/ILO.[79] Patients with nasal complaints should be referred to otolaryngology for complete nasal and sinus evaluation.
Laryngeal sensory discrimination testing
In this investigation an air pulse stimulus is delivered to the laryngeal mucosa (innervated by the superior laryngeal nerve) via flexible nasolaryngoscopy in order to determine its level of sensitivity.[80]
Patients with PVFM/ILO and LPR, as well as those with GERD and cough, have decreased laryngeal sensitivity as assessed with laryngeal sensory discrimination testing.[38][50]
Laryngeal sensory discrimination testing has been reported but it is not routinely performed in all centers, and research is ongoing into its effectiveness.
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