Laryngeal brainstem evoked response: a developmental study

A developmentally receding laryngeal chemoreflex (LCR) has been described in infant animals of several species characterized by vocal cord adduction in response to laryngeal stimulation as well as a potentially fatal cardio-respiratory response. Age-related differences in the brainstem respiratory centers may account for differences in the LCR and play a role in such disorders as Sudden Infant Death Syndrome (SIDS) and infant apnea. Study of the LCR at the brainstem level could provide insights into normal maturation of respiratory centers and eventually the pathophysiology of these disorders. The present study evaluated the laryngeal brainstem response (LBR) evoked by electrical stimulation of the superior laryngeal nerve in kittens using a far-field technique similar to auditory brainstem response testing. Recordings were obtained via posterior pharyngeal and posterior cervical recording sites and compared to results previously obtained in our laboratory for adult cats. The LBR in kittens demonstrated differences in threshold, latencies, and morphology which suggests that postnatal maturation of laryngeal function at the brainstem level does occur.