A piece of anecdotal medical advice was passed on recently that bears sharing in order to set the record straight.
As the story goes, a novice medical provider was told to lightly brush the patient's eye lash and if there was no reflex (blink) the patient's gag reflex would not be intact. Anyone else heard this? If so it is wrong.
The Facial Nerve (CN V) mediates the corneal (eyelash) reflex and the gag reflex is mediated by the Glossopharyngeal and Vagus (CNs IX and X) nerves respectively. These nerves do not share any common pathways and the presence of one does not imply anything about the other. Anesthesia providers often will utilize the method previously outlined to gauge alteration in gross sensory function from a known baseline. And since there is a correlation (although not perfect) between unconsciousness and loss of the gag reflex, there is some value in the lash test but using it in the field while suggestive, isn't the same.
The history of the lash test is that in the OR after administration of an induction agent, an anesthesia provider would lightly brush the eyelashes to check for a blink. The reasoning behind this practice is not so much to check for a gag but to check for unconsciousness prior to the administration of a neuromuscular blocking agent. With no blink present, an anesthesia provider could be reasonably certain they were not paralyzing a patient who is "awake".
Hope this clears that up for anyone who had been using this method in the past.
As the story goes, a novice medical provider was told to lightly brush the patient's eye lash and if there was no reflex (blink) the patient's gag reflex would not be intact. Anyone else heard this? If so it is wrong.
The Facial Nerve (CN V) mediates the corneal (eyelash) reflex and the gag reflex is mediated by the Glossopharyngeal and Vagus (CNs IX and X) nerves respectively. These nerves do not share any common pathways and the presence of one does not imply anything about the other. Anesthesia providers often will utilize the method previously outlined to gauge alteration in gross sensory function from a known baseline. And since there is a correlation (although not perfect) between unconsciousness and loss of the gag reflex, there is some value in the lash test but using it in the field while suggestive, isn't the same.
The history of the lash test is that in the OR after administration of an induction agent, an anesthesia provider would lightly brush the eyelashes to check for a blink. The reasoning behind this practice is not so much to check for a gag but to check for unconsciousness prior to the administration of a neuromuscular blocking agent. With no blink present, an anesthesia provider could be reasonably certain they were not paralyzing a patient who is "awake".
Hope this clears that up for anyone who had been using this method in the past.
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