1. "Vasovagal"
  1. Situational-associated with micturition, defecation, cough, swallow
  2. Generally involves simultaneous vasodilation and bradycardia
  3. May respond to Paroxetine 20mg QD (JACC 33:1227, 1999--JW)
  1. Seizure
  2. Cerebrovascular events
  3. Carotid sinus syncope
  4. Psychogenic
  5. Orthostatic hypotension
  6. "Glossopharyngeal neuralgia" (?) or trigeminal neuralgia
  7. Drug-induced
  8. Cardiac
  1. LV outflow obstruction: AS, IHSS, L. atrial myxoma, MS
  2. RV outflow obstruction: PS, pulm. HTN, PE, Tetralogy of Fallot, R. atrial myxoma
  3. Pump failure (MI)
  4. Pericardial tamponade
  5. Aortic dissection
  6. Arrhythmias

In a retrospective trial of 684 pts with syncope, the following were independently associated with serious outcomes at 7d (e.g. death, MI, PE, CVA, subarachnoid hemorrhage, significant hemorrhage, cardiac dysrthyrmia): abnormal ECG, dyspnea, SBP < 90mm Hg, HCT < 30%, and h/o CHF.  Only 4% of the pts with serious outcomes at 7d had none of these (Ann. Emerg. Med. 43:224, 2004--JW)

Blood levels of Brain Natriuretic Peptide > 40pg/mL, measured on the morning after admission in 118 pts admitted for syncope, had sensitivity of 82% and specificity of 92% for eventual diagnosis of a cardiac cause (Am. J. Cardiol. 93:228, 2004--AFP)In a study in 208 pts with recurrent vasovagal syncope randomized to metoprolol (titrated up to 100mg BID) vs. placebo x 1y, there was no sig. diff. in incidence of recurrent syncope in the two groups (Circ. 113:1164, 2006--JW)


Distinguishing syncope from seizure:

In a split-half prospective study of 671 pts with loss of consciousness (all had extensive w/u to determine etiology, 1/2 given 118-item questionnaire and logistic regression used to determine questions that would predict cause of syncope, the other 1/2 used to validate the decision rule), the following questionnaire & accompanying criteria was found to diagnose seizure with 94% specificity and 94% sensitivity; adding info on # of losses of consciousness or duration of the problem did not increase accuracy:

If total is 1 or more suggests seizures; if < 1 suggests syncope (JACC 40:142, 2002)