Paradoxical vocal fold motion (PVFM) describes inappropriate motion of the true vocal folds. PVFM refers to a clinical phenomenon rather than to one specific or strictly defined clinical diagnosis. PVFM is most commonly observed as inappropriate adduction of the vocal folds on inspiration. Presentation to the emergency room is often wheeze, stridor, or apparent upper airway obstruction. Delay in diagnosis is common, and unnecessary treatments such as intubation and tracheostomy are not uncommon. Patients are commonly frequent users of the health-care system, often over prolonged periods .
While clinical observations of this phenomenon were described in the 1800s, they began to appear with increasing frequency in the 1970s and 1980s with the greater availability of laryngoscopy . PVFM has unintentionally become a catch-all term for functional laryngeal disorders . However, it is important to explicitly define this functional disorder as “impaired function”, emphasizing that this is not synonymous with a psychogenic disorder.
This topic will review the presentation and treatment of PVFM, also called laryngeal dyskinesia, vocal cord dysfunction (VCD), paradoxical vocal cord motion (PVCM), inspiratory adduction, periodic occurrence of laryngeal obstruction (POLO), Munchausen’s stridor, episodic paroxysmal laryngospasm, psychogenic stridor, functional stridor, hysterical croup, emotional laryngeal wheezing, factitious asthma, pseudoasthma, and irritable larynx syndrome [2-5]. Features of wheezing illnesses other than PVFM are discussed separately. (See "Evaluation of wheezing illnesses other than asthma in adults" and "Diagnosis of asthma in adolescents and adults".)
In the normal larynx, the true vocal folds abduct or open during inspiration and partially adduct or close during expiration (figure 1). In addition to inspiration, abduction can also be induced by sniffing and panting. Normal adduction of the true vocal folds occurs with phonation, coughing, throat clearing, swallowing, and during a Valsalva maneuver. Around 10 to 40 percent adduction is normal during expiration. Normal cough mechanics involve vocal fold adduction for 0.2 seconds following the end of inspiratory phase .
Paradoxical vocal fold motion (PVFM) can be seen during inspiration, expiration, or both (figure 1) [2,7,8]. The false vocal folds and supraglottic tissue may also dynamically constrict the airway. It is imperative to visualize full abduction during laryngoscopy to rule out other causes of laryngeal obstruction.