Vasovagal syncope

Introduction Syncope refers to a brief loss of consciousness in a sudden episode, accompanied by a decrease or disappearance of muscle tone, which lasts for a few seconds to a few minutes, and is essentially a temporary reduction in cerebral blood flow. Syncope can be caused by cardiovascular diseases, nervous system diseases and metabolic diseases. However, many patients cannot find the cause based on medical history, physical examination, and auxiliary examination. They have long been called "unexplained syncope." With the development of medical technology, vasovagal syncope (VS) is the most common cause of unexplained syncope in children. According to incomplete statistics, about 80% of syncope belongs to this category.

Cause

Causes of vasovagal syncope

Various stimuli mediate reflexes through the vagus nerve, leading to dilatation of the visceral and muscle small vessels and bradycardia, sudden expansion of peripheral blood vessels, reduction of venous blood return to the heart, so that the heart has a reflex action that accelerates and strengthens contraction, and some people may be over-excited The vagus nerve and parasympathetic nerves, which cause the heartbeat to suddenly slow down and the peripheral blood vessels to dilate, resulting in lower blood pressure, hypoxia in the brain, manifested as arterial hypotension with transient loss of consciousness, self-recovery, and no neurological localization Syndrome.

an examination

Related inspection

Cerebrospinal fluid glucose and serum glucose ratio

Examination of vasovagal syncope

Vasovagal syncope is more common in school-age children, girls than boys, usually appear as standing or sitting up suddenly when syncope occurs, there may be short-term dizziness, inattention, paleness, visual and auditory decline before onset. Aura symptoms such as nausea, vomiting, sweating, and unstable standing can cause a 10-20 second harbinger in severe cases. If you can be alert to this aura and lie down in time, you can ease or disappear. The initial heartbeat often accelerates, the blood pressure can be maintained, the heartbeat slows down, the blood pressure gradually decreases, the systolic blood pressure drops more obviously than the diastolic blood pressure, so the pulse pressure difference shrinks. When the systolic blood pressure drops to 10.7Kpa (80mmHg), the consciousness loss can occur for a few seconds. Or a few minutes, a small number of patients may be accompanied by urinary incontinence.

Differential diagnosis

Symptoms of vascular vagal syncope

Coughing syncope: Loss of consciousness immediately after a severe cough, low muscle tone, short-lived. A small number of patients felt dizzy and dazzled, and their complexion changed from bruising to pale and sweating. Most of the patients were obese men after middle age, who often smoked and had bronchitis and emphysema. Children who developed pertussis or asthma also developed symptoms. Most after repeated coughing, occasionally fainted after a single cough, call, sneezing, yawning or laughing.

Simple syncope: also known as vasopressive syncope, vasovagal syncope. This is the most common type of syncope, accounting for about 90% of all syncope. There are often obvious incentives, such as nervousness, fear, anxiety, pain, seeing bleeding, and hearing bad news. Often occurring in frail young women.

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