Orthostatic syncope is a term describing the loss of consciousness in association with orthostatic hypotension. After suddenly standing up and a sudden drop in blood pressure, patients report fainting episodes and lightheadedness. A detailed patient history and a physical examination, during which serial blood pressure measurements are made, are mandatory components of the diagnostic workup.
When the patient changes from supine to standing position, about 10-15% of all blood pools in the venous system of the lower extremities  . The sudden action of standing up might lead to an abnormal vasomotor response by causing sharp decreases in blood pressure and could result in hypoperfusion of tissues (particularly of the central nervous system)  . This phenomenon is known as initial orthostatic hypotension, characterized by a transient fall of systolic and diastolic pressures of > 40 mmHg and/or > 20 mmHg, respectively   . The inadequate perfusion of tissues seen when initial orthostatic hypotension ensues principally manifests as a transient loss of consciousness (syncope), which may be preceded by dizziness (pre-syncope)  . Orthostatic syncope develops approximately 5-10 seconds after suddenly standing up . Additional symptoms that have been described in the literature are lightheadedness, headaches, visual disturbances, dyspnea, muscle weakness, a transient cognitive decline, and shoulder discomfort  . This form of syncope is especially prevalent among the elderly, in whom baroreceptor activity and the mechanisms involved in blood pressure regulation are not optimally efficient .
The diagnosis of orthostatic syncope rests on the ability of the physician to obtain a detailed patient history and conduct a meticulous physical examination. In fact, the role of a proper patient interview has shown to be pivotal in establishing the underlying cause of syncope . However, the diagnosis of orthostatic syncope can be confirmed by series of blood pressure measurements or continuous blood pressure monitoring   . Some authors recommend that blood pressure should be measured after 5 minutes of lying followed by few measurements after standing up (for 3-5 minutes). Physicians should note whether dizziness and light-headedness appear  . In rare cases, patients may not be able to stay in standing position throughout the entire examination , which is an important clue for the diagnosis of orthostatic syncope. The possibility of constant blood pressure measurement during this period significantly increases the chance of confirming the diagnosis   . Additionally, the head-up tilt test is described in the literature as a possible method to assess orthostatic hypotension . Furthermore, a complete cardiac exam, comprised of electrocardiography (ECG) and cardiac ultrasonography is recommended . The differential diagnosis of orthostatic syncope is quite broad, indicating that a more detailed evaluation (particularly of the central nervous system) might be necessary .