Approach to syncope

What is syncope?

Transient LOC with loss of postural tone (ie unconscious collapse) with spontaneous return to baseline

What is the mechanism of syncope?

Global hypoperfusion of both the cerebral cortices or focal hypoperfusion of the reticular activating system.

Broad causes of syncope

Neurocardiogenic (or reflex)
Orthostatic
Cardiac

Does HR go up or down in neurocardiogenic syncope?

Down (it's usually a vaso-vagal response - mediated by parasympathetics)

Does HR go up or down in orthostatic syncope?

Causes of orthostatic syncope?

1. Primary Autonomic failure (for example, Parkinson's Disease)
2. Secondary: autonomic peripheral neuropathies - (common in diabetes)
3. Iatrogenic
4. Volume depletion

Causes of cardiac syncope?

1. Arrhythmias: eg. bradycardia, VT, brugada and other inherited chanelopathies...pacemaker dysfunction
2. Structural issues: eg. HOCM, valvular disease

Principles of history-taking in syncope - what four parts of the story do you need to find out about?

Background (FHx, PHx)
Before
During
After

What red flags on history are suggestive of cardiac syncope?

Background: risk factors
Before: exertional, chest pain, supine, no warning/prodrome
After: instantaneous recovery

What red flags on history are suggestive of seizure?

Background: PHx epilepsy, not taking medications, precipitants that lower seizure threshhold (eg. no sleep, alcohol withdrawal)
Before: prodrome
During: tonic phase before rhythmic, clonic activity, head deviation or unusual posturing during the episode, loss of bladder or bowel control
After: tongue biting, postictal confusion/disorientation (usually >30min)

Approach to syncope

STUDY

PLAY