Vocal Cord Dysfunction: An Often-misdiagnosed Condition

Sarah M. Jabusch, MS Clinical Research; Timothy M. Hinson, PharmD, AE-C

Disclosures

US Pharmacist. 2017;42(9):34-39. 

In This Article

Airway Anatomy and Physiology

Knowledge of normal laryngeal anatomy and physiology will help the pharmacist understand the etiology of VCD (Figure 1).[6] Important anatomical structures include the larynx (intrinsic and extrinsic muscles), arytenoids, epiglottis, glottis (vocal-fold complex), vocal cords, vocal ligament (true vocal cord), mucosal fold (vocal fold), aryepiglottic folds (false vocal folds), vestibular ligament (false vocal cord), and arytenoid cartilages.[14] The larynx is located in the anterior neck above the trachea.[14] The vocal cords, or vocal folds, are in the midsection of the larynx and stretch horizontally from the thyroid cartilage anteriorly, attaching to the vocal process of the arytenoid cartilage posteriorly.[6,14] Contraction of the thyroarytenoid, interarytenoid, and lateral cricoarytenoid muscles causes adduction of the vocal cords.[14] The respiratory movements of the vocal cords are coordinated with those of the diaphragm and other muscles of the ventilator pump.[15] A complex innervation of muscles and nerves causes the larynx to adduct and abduct the vocal cords.[14–16] The lateral cricoarytenoid and posterior cricoarytenoid muscles and the vagus, recurrent laryngeal, and superior laryngeal nerves are involved in this process.[14–16] The vocal cords begin to separate just before the diaphragmatic contraction, which is mechanically advantageous.[14] Sensory fibers in the intercostal nerves can affect laryngeal movements, but the responses are complex.[14] These coordinated movements result in the vocal cords moving away from the midline during inspiration and slightly toward the midline during expiration.[16]

Figure 1.

Reprinted with permission from Medscape Drugs & Diseases (http://emedicine.medscape.com/), 2017, available at: http://emedicine.medscape.com/article/1949369-overview.

Under normal conditions, the vocal cords form a V-shaped opening that is narrowest anteriorly when viewed from the upper airway.[14–16] Figure 2A demonstrates vocal cord abduction during normal inhalation, and Figure 2B shows the vocal cords during normal phonation. In patients with VCD, however, only the anterior two-thirds of the vocal cords adducts during inspiration and there is a posterior diamond-shaped chink (lack of full closure).[14–16] Figure 2C demonstrates vocal cord adduction (paradoxical movement) and the diamond-shaped chink. This can be detected only by direct observation with flexible laryngoscopy, which is the gold standard to confirm the presence of VCD.[9]

Figure 2.

A (left): Vocal cord abduction during normal inhalation. B (center): Vocal cords during normal phonation.C (right): Vocal cord adduction (paradoxical movement) demonstrating the diamond-shaped chink.Source: Sarah M. Jabusch.

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