An Experimental Study of Superior Laryngeal Nerve Brain Stem Evoked Response in the Dog

Kim, Kwang Moon; Kim, Young Ho

Abstract

BACKGROUND AND OBJECTIVES: Laryngeal protective reflex is a glottal closure reflex triggered by the tactile receptors in the glottic and supraglottic mucosa, which evoke reflexive contraction of laryngeal musculature. Exaggeration of this normally protective reflexes is thought to be responsible for several disorders, including the sudden infant death syndrome. Although the laryngeal brain stem evoked response (LBR) has been studied in several species of animals, dogs were not used as an experimental model yet. The purposes of this study are to record the far-field brain stem activity and to record the waveforms in the dog which has the larynx most similar to that of human, anatomically and physiologically.
MATERIALS AND METHODS
Under general anesthesia, the LBR tracings were recorded following direct electrical stimulation of the internal branch of the superior laryngeal nerve (SLN) in 5 dogs.
RESULTS
1) Mean latency of laryngeal adductor reflex response was 12.15 msec. 2) A total of four reproducible positive waves and three negative waves were detected, with mean latencies ranging 2.09-6.11 msec. 3) After sectioning the SLN, no waves were reproducible except for the triggering artifact.
CONCLUSION
These results suggest that the pattern of waves obtained in the present canine model shows similarity to those of other animal models. In addition, the evaluation and normalization of the data in the present canine model could be used to support future clinical application of human LBR.