[Neurally mediated syncope starting in young or in old age: different prognostic significance?]

Neurally mediated syncope (NMS) is the clinical manifestation of the vasovagal reflex activation. Prognosis of this type of syncope is reported as "benign", mainly on the basis of the results of the Framingham study, in which the incidence of mortality, cardiovascular and cerebrovascular events did not differ from that of the control population. However, in this study NMS starting in young age and that starting in advanced age were investigated together, but some elements suggest that we are dealing with two different clinical entities, even if the efferent pathways of the reflex circuit appear to be the same. While it is largely accepted that NMS starting in young age is a manifestation of a non-pathological trait, some lines of evidence suggest that NMS starting in old age is the expression of a pathological process of the autonomic nervous system, up to now not well defined from the nosological point of view: (i) onset in old age per se, (ii) absence of triggers, which means "abnormal activation" (pathological) of the vasovagal reflex, (iii) frequent overlap with situational syncope, carotid sinus hypersensitivity, orthostatic or post-prandial hypotension and other dysautonomic symptoms, and (iiii) it appears to be the human homologue of a recently described syncope starting in dogs in advanced age; in other words, humans and dogs seem to suffer from the same disease. On the basis of these considerations, in future studies the prognostic significance of NMS starting in old age should be investigated separately. At present, the prognosis of NMS, in relation to hard events, remains undefined in the elderly.