Inducible Laryngeal Obstruction (ILO), Vocal Cord Dysfunction (VCD)

Inducible laryngeal obstruction is an inappropriate, transient, reversible narrowing of the larynx to external or internal triggers. The true vocal folds, false vocal folds or supraglottic tissue can dynamically constrict airway. VCD is an older term that specifically refers to the more narrow description of vocal folds adducting inappropriately during inspiration, expiration or both.

Exercise induced laryngeal obstruction (EILO) narrowing of the laryngeal airway either at the vocal folds (glottic) or supraglottic (above the glottis) during exercise.

Triggers

Exercise, Irritants (e.g. smoke, cleaning fumes), Asthma (bronchoconstriction induces or can be commensal with laryngeal obstruction), post-extubation (laryngospasm is an acute brief event vs ILO is recurrent), Laryngopharyngeal reflux, neurologic injury (recurrent laryngeal nerve involvement), Psychosocial disorders and stress (e.g. anxiety, depression, PTSD)

Symptoms

Dyspnea, throat tightness, choking sensation, dysphonia, cough, GER, dysphagia, if exercise induced usually occurs with maximal exercise. Noisy breathing can be heard on inspiration or expiration and is most audible over neck. Albuterol is not as beneficial.

Diagnosis

Clinical History is most often but laryngoscopy is gold standard.

Pulmonary function testing: ILO or VCD can be difficult to confirm or exclude by PFT alone, usually flattening of inspiratory loop of flow volume curve is described though technique can limit evaluation.

Exercise or methacholine challenge has been used to induce an ILO exacerbation.

Laryngoscopy: Gold Standard. Obstruction can be seen in supraglottic (arytenoids, epiglottis, false vocal folds) or glottic (true vocal folds) or both areas.

Layperson’s explanation

When normal breathing occurs true vocal folds open (abduct)during inspiration, and normally partial close (adduct about 10-40%) during expiration. Adduction of the vocal folds occur with speaking, coughing, throat clearing, swallowing. VCD can happen when there is closure of the vocal folds when it is supposed to be open. In asthma, asthma can trigger a VCD episode, but can also make asthma seem uncontrolled or difficult to control. In asthma triggered VCD, this can occur on inspiration, but sometimes even on expiration and improves when asthma is well controlled.

Differential diagnosis

Asthma, laryngospasm, laryngeal angioedema, vocal fold motion abnormalities, excessive dynamic airway collapse, laryngeal stenosis.

Treatment

Treatment of VCD includes identification of triggers of VCD, speech therapy, and treatment of those triggers.

Acute episodes: Reassurance, positive airway pressure

Long term: Speech Therapy is first in line of care, control asthma and other triggers; psychotherapy for emotional triggers. Botox has been discussed for refractory cases