Reflex syncope

This is one of the most common causes of syncope, estimated at 35-50%, and about 30% of people have survived at least one faint - and many more will have witnessed fainting! Vasovagal syncope is the "common faint" but it can be difficult to differentiate "faints" from other causes of syncope.

Reflex syncope is neurally modulated and can be split into three main groups:
- Vasovagal (emotional eg Blood and orthostatic stress)
- Situational (cough, sneeze, defaecation, micturition, post-exercise, post-prandial)
- Carotid sinus syncope

Signs and Symptoms
Transient loss of consciousness
Jerky movements similar to a seizure
May be associated with palpitations, blurred vision, and feelings of nausea, warmth and light-headedness prior to the syncope episode, and patients are more likely to have had previous syncopal episodes.

Pathophysiology
This arises from an initial increase in sympathetic outflow followed by a rebound reduction in sympathetic activity leaving unopposed parasympathetic activity causing vasodilatation, bradycardia and hypotension.
In other word, you get worried about something, so get the flight or fight response. This then stops, and the unopposed activity makes you collapse. 

Investigations
Look for carotid sinus hypersensitivity in any patient older than 40. A ventricular pause lasting >3 seconds or fall in BP of 50mmHg defines carotid sinus hypersensitivity.


Treatment
Exercises to improve blood flow
Driving - no restriction