Temporary but complete abolition of the gag reflex is easily and quickly achieved with intraorally administered lidocaine (Xylocaine) block of the glossopharyngeal nerve. The technique is routinely employed for awake nasotracheal intubation, local tonsillectomies, and, in combination with superior laryngeal nerve blocks, all forms of local peroral endoscopy. No complications have occurred in experience with over 130 patients. It is hypothesized that proprioceptive receptors in the posterior one third of the tongue are pressure sensitive, and that when stimulated, they may, independently of their fellow tactile receptors, initiate the afferent limb of the gag reflex.
Barton S, Williams JD. Glossopharyngeal Nerve Block. Arch Otolaryngol. 1971;93(2):186–188. doi:10.1001/archotol.1971.00770060272014