External Branch of the Superior Laryngeal Nerve Mediated Glottic Closing Force in the Porcine Model

Abstract

The GCF obtained during isolated eSLN stimulation is adequate for delivery of an appropriate laryngeal protective response and may be considered a target motor nerve for augmenting GCF in selected rehab settings.

Swallowing disorders after thyroidectomy: What we know and where we are. A systematic review

“…Its lesion can determine, in some cases, dysphagia and aspiration [7] while the external branch (EB-SLN) provides the motility of the cricothyroid muscle, which improves the tension of the vocal folds but its damage is occasionally followed from various rates of swallowing symptoms [23,27]. As confirmed in animal models, the EB-SLN provides the laryngeal protective response so a damage of this branch can be involved in dysphagia [28]. The RLN, that arises from a contingent of fibers of the vagus nerve in the anterior mediastinum, anteriorly the aortic arch, innervates all the intrinsic laryngeal muscles except the cricothyroid one [1].…”

In search of a longitudinal animal model of evoked swallow function

“…Finally, motor neurons project through the recurrent laryngeal nerve (RLN) to supply the thyroarytenoid (TA) muscle and other vocal fold adductors, leading to protective reflex glottis closure . In previous studies, our laboratory has quantitatively characterized the glottic closure reflex in the form of stable and reproducible measures …”

“…Although further effort should be directed to determine the optimal parameters to evoke swallowing under general anesthesia, the observations obtained from our current study suggest the parallel exploration of surrogate markers for evoked swallow function to be used for the assessment of future therapeutic interventions. 9,43 The glottic closure reflex (GCR) is typically elicited during the pharyngeal phase of swallow and plays a pivotal role in the protection of lower airway from invasion of material 44 that may lead to aspiration pneumonia. 2 GCR may be a possible surrogate not only because it clinically serves as an essential component of the swallow reflex, but more essentially because it shares many of the same central nuclei in the generation of the more global swallow reflex response.…”

“…43,46,47 In previous studies, our laboratory has quantitatively characterized the glottic closure reflex in the form of stable and reproducible measures. 9 Further estimation of the difference in complexity between GCR and swallow reflex can alternatively be expressed in a theoretical perspective by the difference in latency of both reflexes and the estimated number of interneurons involved in each reflex. We can turn to two historical sources for synthetic data to guide our calculations.…”

“…Most intravenous or inhalational anesthetic agents commonly increase the responsiveness of gamma amino butyric acid (GABA) receptors, enhancing their inhibitory neural behavior . Intravenous dexmedetomidine has been previously used for the study of glottic closure reflex while intravenous ketamine is a dissociative agent that seems to preserve the swallow reflex in human subjects . It has also been used successfully in porcine models for the study of laryngeal reflexes …”