Paradoxical vocal cord motion (PVCM) refers to inappropriate movement of the vocal cords, which results in functional airway obstruction and inspiratory or expiratory stridorous breathing. Patients with PVCM are often misdiagnosed with asthma, because the sound produced can be mistaken for asthmatic wheezing.
This topic will review the presentation and treatment of PVCM, also called vocal cord dysfunction, Munchausen stridor, psychogenic stridor, factitious asthma, pseudoasthma, and irritable larynx syndrome [1-3]. Features of wheezing illnesses other than PVCM 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 cords abduct on inspiration, opening the glottis, and adduct partially during expiration, closing the glottic aperture about 10 to 40 percent. Normal inspiratory abduction is controlled by the vagus nerve; inspiratory abduction can also be induced by sniffing and panting. Normal adduction of the true vocal cords occurs with phonation, swallowing, and during a Valsalva maneuver. Normal cough mechanics also involve vocal cord adduction for 0.2 seconds following the end of inspiratory phase; this is called the compressive phase as the expiratory muscles initiate shortening against a closed glottis; finally, the vocal cords abduct and forceful exhalation ensues .
In PVCM, adduction of the true vocal cords occurs on inspiration, expiration, or both [3,5,6]. The false vocal cords may also adduct abnormally and the posterior laryngeal wall may move anteriorly to compress the airway.
PVCM has been associated with psychosocial disorders, stress, exercise, perioperative airway and neurologic injury, gastroesophageal reflux, and irritant inhalational exposures. Some patients have concomitant asthma or have been misdiagnosed with asthma .