Clinical features:
(1) recurrent episodes with loss of consciousness
(2) hypotension during the episode
(3) variable apnea during the episode
(4) variable warning symptoms prior to the episode (sweating, pallor, nausea, headache, lightheadedness, etc)
(5) symptoms after the episode (headache, lethargy, weakness) that clear within an hour
Features make "malignant" in the absence of underlying cancer:
(1) frequent
(2) associated with serious injury
(3) result in significant clinical impairment
Nonmalignant causes:
(1) Wolff-Parkinson-White syndrome
(2) episodes of cardiac asystole
Tumors can result in vasovagal syncope with:
(1) compression of the vagus nerve along its course
(2) compression of the carotid body
(3) expansion within the middle ear
