Differential Diagnosis of Vasovagal Syncope

The clinical presentation of vasovagal syncope (VVS) may vary widely: typical VVS, atypical VVS, unexplained fall, and "sleep syncope". Therefore, the differential diagnosis may sometimes be difficult. The diagnosis of typical VVS is usually easy, but when the presence of a trigger (emotional or orthostatic) is uncertain, the diagnosis becomes uncertain. The absence of a clear history and the possibility of multiple etiologies make the diagnosis of atypical VVS difficult to establish in some patients. Depending on the clinical features, the differential diagnosis of atypical VVS of other reflex syncopes such as situational syncope and carotid sinus syncope, orthostatic syncope and cardiac syncope, and unexplained falls and nonsyncopal loss of consciousness should be made. When witnesses report myoclonic movements, the differential diagnosis of epilepsy should be made. A tilt test is helpful to differentiate between VVS and an unexplained fall.