• Keisuke Shiba, Shiroh Isono, Yasuko Sekita, and Atsuko Tanaka.
• Department of Otolaryngology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chiba 260-8670, Japan. shiba@med.m.chiba-u.ac.jp
• Laryngoscope. 2004 Feb 1;114(2):372-5.

Objectives/HypothesisIn patients with restricted abduction of the vocal cords, it has generally been accepted that glottis narrowing with laryngeal stridor during inspiration is attributed to static and passive obstruction of the glottis. However, active glottis narrowing can also be contributory. We tested the hypothesis that the vocal cord adductor is activated during inspiration in patients with restricted abduction of the vocal cords.Study DesignElectromyographic evaluation of vocal cord adductor activity in patients with restricted abduction of the vocal cords.MethodsFive patients with restricted abduction of the vocal cords who had stridor with mild to severe dyspnea during wakefulness were anesthetized with propofol. We recorded the adductor muscle electromyogram during breathing through a laryngeal mask airway while observing the vocal cord movement endoscopically. In three patients who had undergone tracheostomy, we also recorded adductor firing patterns not only while closing but also while opening the tracheostoma.ResultsThe adductor was activated during inspiration, and the glottis was narrowed in accordance with inspiratory stridor. This adductor inspiratory activity was abolished by opening the tracheostoma in the tracheostomized patients.ConclusionNot only static or passive glottis narrowing but also active narrowing may contribute to inspiratory flow limitation in patients with restricted abduction of the vocal cords. This active glottis narrowing is probably induced by an airway reflex.

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