Autonomic Mediated Syncope
Autonomic Mediated Syncope (Vasovagal Syncope, Malignant Vasovagal Syncope, Neurally Mediated Syncope, Neurocardiogenic Syncope) may present for the first time at any age. It often occurs when upright, though can occur when sitting. It rarely occurs when lying. There often are no precipitating circumstances though attacks are more likely to occur in certain situations, for example during a large meal in a warm restaurant, when watching a production in a hot theatre, when flying or after prolonged standing.
The onset may be abrupt or associated with prodromal fatigue, weakness, nausea, sweating, pallor, visual disturbance, abdominal discomfort, headache, pins-and-needles, light-headedness or vertigo. Presyncope may last for seconds or minutes. This prodromal phase may be absent in older individuals.
If syncope ensues, the individual usually lies still while unconscious, though occasionally s/he may convulse briefly. (Prolonged convulsions, blue face, or tongue biting at the time of collapse, and prolonged confusion and aching muscles afterwards help distinguish a true primary seizure from one secondary to vasovagal syncope. Sleepiness and urinary incontinence are of less value in making the distinction).
On recovery of consciousness following syncope the person may complain of nausea, clamminess, light-headedness, headache and malaise and may be unable to stand up for several minutes. Full recovery may take some hours. There is a significant incidence of injury associated with vasovagal syncope. Interestingly, co-existing heart disease is rare.