Some psychological conditions (anxiety disorder, somatic symptom disorder, conversion disorder) may cause symptoms resembling syncope. A number of psychological interventions are available.Low blood sugar can be a rare cause of syncope.Narcolepsy may present with sudden loss of consciousness similar to syncope. Diagnostic approach
A medical history, physical examination, and electrocardiogram (ECG) are the most effective ways to determine the underlying cause of syncope. Guidelines from the American College of Emergency Physicians and American Heart Association recommend a syncope workup include a thorough medical history, physical exam with orthostatic vitals, and a 12-lead ECG. The ECG is useful to detect an abnormal heart rhythm, poor blood flow to the heart muscle and other electrical issues, such as long QT syndrome and Brugada syndrome. Heart related causes also often have little history of a prodrome. Low blood pressure and a fast heart rate after the event may indicate blood loss or dehydration, while low blood oxygen levels may be seen following the event in those with pulmonary embolism. Routine broad panel laboratory testing detects abnormalities in <2–3% of results and is therefore not recommended.Based on this initial workup many physicians will tailor testing and determine whether a person qualifies as high-risk, intermediate risk or low-risk based on risk stratification tools. More specific tests such as implantable loop recorders, tilt table testing or carotid sinus massage may be useful in uncertain cases. Computed tomography (CT) is generally not required unless specific concerns are present.
Those who are considered at high risk following investigation may be admitted to hospital for further monitoring of the heart.Syncope affects about three to six out of every thousand people each year. It is more common in older people and females. It is the reason for one to three percent of visits to emergency departments and admissions to hospital. Up to half of women over the age of 80 and a third of medical students describe at least one event at some point in their lives. Of those presenting with syncope to an emergency department, about 4% died in the next 30 days. The risk of a poor outcome, however, depends very much on the underlying cause. Causes
Causes range from non-serious to potentially fatal. There are three broad categories of causes: heart or blood vessel related; reflex, also known as neurally mediated; and orthostatic hypotension. Issues with the heart and blood vessels are the cause in about 10% and typically the most serious while neurally mediated is the most common. There also seems to be a genetic component to syncope. A recent genetic study has identified first risk locus for syncope and collapse. The lead genetic variant, residing at chromosome 2q31.1, is an intergenic variant approximately 250 kb downstream of the ZNF804A gene. The variant effected the expression of ZNF804A, making this gene the strongest driver of the association. Neurally mediated syncope
Reflex syncope or neurally mediated syncope occurs when blood vessels expand and heart rate decreases inappropriately leading to poor blood flow to the brain.