Self-diagnosis of orthostatic hypotension in a patient with autonomic failure

Orthostatic faints are most readily identified by a careful medical history in which the association with posture is documented (i.e. syncope occurring shortly after changing from a lying or sitting to a standing position or prolonged orthostatic stress). It is of particular importance for patients to identify reversible causes of orthostatic hypotension like volume depletion and the effect of medication[2][3]. The drugs most frequently associated with orthostatic syncope are vasodilators and diuretics[4]. Alcohol can also be associated with orthostatic syncope, by causing orthostatic intolerance (vasodilation and volume depletion) as well as inducing autonomic and somatic neuropathy. Elimination of the responsible drug or offending agent usually is enough to improve symptoms.

In a small minority of cases orthostatic hypotension is caused by impairment of autonomic reflexes required for maintaining blood pressure in the upright position[5]. This disorder is called autonomic failure[2]. Autonomic failure can be due to a primary disease (pure autonomic failure, multiple system atrophy), secondary to other diseases (diabetes, amyloidosis) affecting the autonomic nervous system or due to drugs[2]. Orthostatic hypotension due to primary autonomic failure typically occurs in older male adults. Almost without exception, they have a history of erectile and urinary tract dysfunction[2][3].

With a significant and persistent decrease in arterial pressure characteristic features occur. Symptoms include lightheadedness and blurring of vision. A neck ache radiating to the occipital region of the skull and to the shoulders (coat hanger distribution) often precedes actual loss of consciousness. The postulated mechanism of this virtually unique symptom of postural hypotension is ischemia in continuously contracting postural muscles. Other symptoms suggesting impaired perfusion of muscle tissue are lower back and buttock ache or angina pectoris. Typically symptoms develop in minutes on standing or walking and resolve on lying down [2][6]. Patients with autonomic failure quickly learn to use these symptoms as a warning signal that they must lie down to restore an adequate perfusion pressure. If the patient remains upright a gradual fading of consciousness occurs and the patient slowly falls to his knees. Sudden postural attacks and true syncope may, however, also occur. Symptoms and signs of autonomic activation like sweating or a vagally induced bradycardia are absent in patients with autonomic failure. Orthostatic syncope can be diagnosed when there is documentation of orthostatic hypotension associated with syncope or presyncope. Carefully measuring blood pressure with a sphygmomanometer supine and after standing suffices for the routine assessment of orthostatic blood pressure control in the office or at the bedside. For the diagnosis of orthostatic hypotension, arterial blood pressure must be measured when the patient adopts the standing position after 5 minutes in supine position. Orthostatic hypotension is defined as a decline in blood pressure of at least 20 mmHg systolic and / or 10 mmHg diastolic within 3 minutes of standing, regardless whether or not symptoms occur[2]. If the patient does not tolerate standing for this period, the lowest systolic blood pressure during the upright position should be recorded. Measurements should be continued after 3 minutes of standing if blood pressure is still falling at 3 minutes. In some patients with syncope and a history suggestive of impaired orthostatic blood pressure control blood pressure measurements in upright position may be normal. In these patients additional tests, using provocative stimuli as food ingestion and exercise, may be needed to unmask orthostatic hypotension. A useful alternative is a 24 hour or longer ambulatory blood pressure recording under daily circumstances, similar to those associated with symptoms in the individual patient.