Why 'stimulating the vagus' is never one single intervention.
Your vagus nerve is constantly sending signals up from your organs to your brain and back down — handling reflexes you don't think about, like swallowing, coughing, slowing your heart when you stand still too long, and telling your brain when your stomach is full.
Vagovagal reflex arcs underpin cough, gag, and Bezold-Jarisch–type cardioinhibitory responses. Important for syncope evaluation and stimulation planning. Recall: large myelinated A-fibers have lowest electrical threshold; small unmyelinated C-fibers (which carry much of the visceral afferent traffic) require higher current.
Organ- and function-specific fascicular organization (Settell et al., Brain Stim 2023+) is reshaping precision VNS device design. Selective stimulation of efferent vs afferent fibers, and of cardiac vs pulmonary vs immune-relevant pathways, is the frontier.
Fiber-type recruitment explains why Tier 1 implanted VNS and Tier 4 investigational devices behave so differently.
About 80% of vagal fibers carry sensory information from organs to the brain; only ~20% are motor/efferent.
Short patient encounters that test your judgment, not your recall. Pick the most defensible response, then reveal the rationale and a sample coaching script you could actually say at the bedside.
A 22-year-old fainted while standing in line, with prodromal nausea and pallor. Tilt-table testing reproduced bradycardia and hypotension.
A patient titrating implanted VNS reports stronger throat sensation as current rises but no extra antiseizure benefit at higher doses.
A new VNS patient develops a productive cough during stimulation cycles in the first month.