Eric W. Cohen, MD, Steven Weiner, MD,Paul W. Flint, MD

The laryngeal reflexes mediate glottic closure, apnea, and bradycardia. Previous studies of the laryngeal adductor reflex necessarily utilized anesthesia, a potentially confounding variable. In this study, a decerebrate adult cat model was used to define the laryngeal reflex in the absence of cortical influences and general anesthesia. The superior laryngeal nerve is stimulated electrically and physiologic recordings are obtained at the ipsilateral and contralateral recurrent laryngeal nerves (compound action potential) and the thyroarytenoid muscle (electromyography). In the normal cerebrate condition, there is an increase in threshold and latency of the contralateral response. In the decerebrate condition, there is a significant decrease in the ipsilateral and contralateral thresholds. while the suprathreshold latency is unchanged. These findings suggest cortical inhibitory influences are released following decerebration. Alternatively, cc] I ular changes in the brain stem due to central injury may result in increased sens itivity of the laryngeal adductor reflex.