Laryngopharyngeal sensory discrimination testing and the laryngeal adductor reflex

Laryngopharyngeal sensory capacity has been determined by endoscopically ad ministering air pulse stimuli to the mucose innervated by the superior lary ngeal nerve and asking the patient if he or she feels the stimulus. A poten tial shortcoming of this psychophysical testing (PT) procedure is that it i s a subjective test, and patients with impaired cognition may not be able t o perform the required task. In the search for an objective measure of lary ngeal sensory function, we have observed that the laryngeal adductor reflex (LAR) is evoked at stimulus intensities similar to those capable of elicit ing the psychophysical, or perceptual, response. The purpose of this study is to determine if the threshold for eliciting the LAR is the same as that of the sensory threshold. A specially designed endoscope was used to presen t air pulse stimuli (range 0.0 to 10 mm Hg) to the laryngopharynx in 20 hea lthy subjects and in 80 patients with dysphagia, using both PT and the LAR. The patients had a variety of underlying diagnoses, with stroke and chroni c neurologic disease predominating (n = 65). In the control group and in th e group of patients with dysphagia, there was no statistically significant difference between the median laryngopharyngeal sensory thresholds whether we used PT or the LAR (p > .05, Wilcoxon signed-rank test). The intraclass correlation for the total sample was .999 (U = .999, L = .998). Since psych ophysical and sensorimotor reflex thresholds were not statistically signifi cantly different and the intraclass correlation was close to a per-feet cor relation, we conclude that the LAR can be used as an objective and accurate clinical method of endoscopically assessing laryngopharyngeal sensory capa city.