Methodology for eliciting the brainstem trigeminal-hypoglossal reflex in humans under general anesthesia

Objective: Brainstem trigeminal-hypoglossal reflexes (THRs), also known as the jaw-tongue reflexes, coordinate the position of the tongue in the mouth in relation to the jaw movement during oromotor behaviors such as mastication, swallowing, vocalization, and breathing. Their use in brainstem surgery however, has never been assessed in spite of its potential benefit possibly due to the lack of a methodology to elicit these reflexes under general anesthesia. Methods: We proposed a technique to elicit the THRs during total intravenous anesthesia (TIVA) consisting on a V3 infrazygomatic train stimulation paradigm and recording from the Styloglossus (31 patients) and the Genioglossus (21 patients) muscles to elicit long latency responses. Results: The THR was successfully recorded using the V3 stimulation point in 82.1% of patients, of which 96.9% presented a response on the Styloglossus muscle (Jaw-opening reflex) while 0.06% presented a response on the Genioglossus muscle instead (Jaw-closing reflex). Conclusions: The THRs can be successfully recorded in surgery under general anaesthesia with the predominant reflex seen being the jaw-opening reflex. Significance: We provide a novel method to elicit the THRs during general anesthesia, which could be of aid in brainstem surgery. (c) 2022 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Automated summary

A study successfully recorded brainstem trigeminal-hypoglossal reflexes (THRs) under general anesthesia, with the predominant reflex being the jaw-opening reflex. The findings have important implications for brainstem surgery.