It is important to differentiate true syncope from other causes of collapse/loss of consciousness that do not occur from cerebral hypoperfusion. NOTE: rare causes of syncope may exist including vascular steal syndrome (shunting of blood due to an obstructed upper limb arterial vessel) and vertebrobasilar insufficiency (poor blood flow through the posterior circulation of the brain, but usually occurs with other preceding symptoms).
#Cataplexy vs syncope full
Visual alteration: usually described as blurring, then temporary darkening of visionĪlthough the loss of consciousness is brief (~8-12 seconds), there may be some fatigue after the event with full recovery slightly delayed.Prior to the onset of loss of consciousness, typical features can occur that are related to changes in the autonomic nervous system. This is why lying patients down is recommended following a collapse. lying down) helps maintain adequate cerebral perfusion. This is because the supine position (i.e. Vasovagal syncope typically occurs in the standing or sitting position.
#Cataplexy vs syncope series
Vasovagal syncope is classically associated with a series of prodromal symptoms including nausea, pallor and sweating. Other autonomic pathways may be involved including the baroreceptor reflex and carotid sinus reflex. In vasovagal syncope, there is usually a combination of both cardioinhibitory and vasodepressors mechanisms, which is known as a ‘mixed response’. Vasodepressor response: decreased sympathetic activity that leads to systemic vasodilatation and subsequent hypotension.Cardioinhibitory response: increased parasympathetic activity that causes altered electrical activity in the heart manifesting as bradycardia (or higher degree of heart block).Looking at these mechanisms in more detail, there are two major responses in vasovagal syncope: The cerebral hypoperfusion results in the temporary loss of consciousness. The result of these two mechanisms is a fall in blood pressure (hypotension) and subsequent reduction in cerebral perfusion (hypoperfusion). Broadly speaking, these reflex responses result in: Vasovagal syncope is a neurally-mediated condition that results in reflex changes in the autonomic nervous system. micturition) this is known as a ‘situational syncope’ as discussed above. When there is a very specific trigger (e.g. Instead, there may be a history of recurrent syncope without apparent cause. Some patients may have no specific trigger, particularly in the elderly. Vasovagal syncope, particularly in young patients, may be associated with specific triggers that lead to reflex autonomic nervous system changes. Baroreceptors are mechanoreceptors that sense arterial stretch and alter blood pressure through the autonomic nervous system. Carotid sinus syndrome: exaggerated response to carotid sinus baroreceptor stimulation.Situational syncope (faint in response to a specific trigger): coughing, swallowing, sneezing, micturition.Vasovagal syncope is a type of ‘reflex syncope’ that causes loss of consciousness due to a reflex response in the autonomic nervous system.
Vasovagal syncope is due to altered activation of the autonomic nervous system.
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