Mechanisms:
(1) increased vagal nerve action
(2) decreased preload (decreased cardiac filling, peripheral venous pooling)
(3) sympathetic withdrawal following overstimulation
Types of situations that can produce situational syncope:
(1) micturition (urination)
(2) defecation
(3) swallowing (deglutition)
(4) glossopharyngeal neuralgia (associated with pain the posterior pharynx or external auditory canal)
(5) postprandial (after eating)
(6) cough (tussive)
(7) sneezing
(8) valsalva maneuver
(9) oculovagal (pressure on the eyeballs)
(10) instrumentation
(11) diving
(12) post-exercise (needs to be distinguished from post-exertional syncope associated with cardiac disease)
The final diagnosis depends on exclusion of more serious underlying causes of syncope. This may be relatively easy in a young, healthy person, but may be more challenging in an older patient.
