The term EILO (exercise-induced laryngeal obstruction) is a general term, covering several conditions. First and foremost, they occur during exercise, not to be confused with other conditions, which occur at rest or as a reaction to a stimulus other than exercise.
There is some confusion among doctors and researchers as to the naming of the conditions. Here, we offer our understanding of the conditions.
The normal larynx
At rest, as well as during exercise, the larynx should look like this during inspiration. Note the supra-glottic mucosa and cartilages positioned well away from the opening to the trachea, as well as the vocal chords positioned to the side. This allows for maximal air flow through the triangular-shaped opening to the trachea.
Glottic obstruction / Vocal Chord Dysfunction
During inspiration, the vocal chords should maintain a position to the side of the tracheal entry in order to allow air to pass through. In Vocal Chord Dysfunction (VCD), the vocal chords instead approach eachother, making less room for air to pass. The amount of closure can vary from barely visible to complete closure, depending on the severity of the VCD. In some patients, VCD occurs only during exercise, yet, in others, VCD attacks can happen at rest.
Supra-glottic obstruction / Exercise-induced Laryngomalacia
During inspiration, the vocal chords are positioned as they should be, to the side. The mucosa and cartilages surrounding the entry to the trachea should also not block air flow. However, in EIL, the mucosa and cartilages move toward the center, covering some or all of the opening to the trachea. This only happens during physical exertion – At rest, the larynx looks normal.
Mixed glottic and supra-glottic obstruction
A combination of the two conditions can also exist.