Cardiac syncope due to dysrhythmia
Cardiac syncope due to structural abnormalities
The incidence of vasovagal syncope actually decreases with age due to decreased responsiveness of the autonomic nervous system. Orthostatic hypotension is common in the elderly due to a less-sensitive thirst mechanism and a decreased endocrine response to volume depletion. Orthostatic hypotension is also related to increased medication use in older patients. Advancing age increases the risk of syncope but cardiovascular risk is thought to be a better predictor. Cardiac syncope due to dysrhythmias or structural conditions is very common and more likely with increasing age. Neurologic syncope is a rare cause of syncope at any age, since it must be transient and allow a return to baseline neurologic function. Vertebrobasilar insufficiency can transiently affect the reticular activating system and cause a brief loss of consciousness, but other posterior circulation signs and symptoms also occur, such as vertigo or diplopia.