It is a sudden, transient loss of consciousness caused by cerebral ischemia and hypoxia, often classified into three categories: cardiac, cerebral, and reflex vasogenic.

bubble_chart Diagnosis

1. History Taking

Syncope often involves sudden loss of consciousness, falling, pale complexion, cold limbs, absence of spasms, tongue biting, or urinary incontinence. It is important to inquire about the circumstances before syncope, the presence of any prodromal symptoms, the degree and duration of impaired consciousness during syncope, and whether there were accompanying symptoms such as pale complexion, slow pulse, urinary incontinence, or limb twitching. Syncope is often triggered by emotional stimuli such as grief, fear, anxiety, needle phobia, sight of blood, trauma, severe pain, stuffiness, or fatigue. Other triggers may include urination, defecation, coughing, blood loss, or dehydration. The patient's body and head position during the episode should also be noted. Orthostatic hypotension syncope often occurs when transitioning from lying to standing, while carotid sinus hypersensitivity syncope is more likely to occur with sudden head movements.

2. Physical Examination Findings

Cardiac syncope is often associated with valvular heart disease, arrhythmias, or myocardial ischemia, and auscultation may reveal heart murmurs or irregular rhythms. Syncope caused by insufficient blood supply from the carotid or vertebral arteries may present with weakened or absent carotid pulse on one side, abnormal vascular murmurs, or syncopal episodes during neck rotation or head extension tests. Syncope due to brainstem lesions may present with crossed paralysis, crossed or dissociated sensory deficits, or other brainstem signs. Conditions such as Takayasu's arteritis or subclavian steal syndrome may present with significantly reduced blood pressure in one arm and vascular murmurs over the neck or supraclavicular fossa. Primary orthostatic hypotension is diagnosed when the blood pressure difference between lying, sitting, and standing positions is ≥50mmHg.

Electrocardiography and cardiac ultrasound are suitable for diagnosing cardiac syncope. Brain CT, cerebral angiography, cerebrospinal fluid examination, cervical spine X-rays, and carotid/vertebral artery ultrasound are useful for diagnosing cerebral syncope. Electroencephalography is typically normal.

bubble_chart Treatment Measures

1. Disease Cause Treatment

For those with clear predisposing factors, avoidance is recommended; for those with a clear disease cause, early disease cause treatment should be initiated.

2. Symptomatic Management and Prevention of Episodes

For recurrent orthostatic hypotensive syncope, Ritalin 10mg or ephedrine 12.5–25mg, 2–3 times daily, may be taken; avoid rapid postural changes. For micturition syncope, advise reducing water intake before bedtime and avoiding excessive urine retention, as well as refraining from standing urination. For carotid sinus reflex syncope, advise against overly tight or high collars. For breath-holding syncope, avoid prolonged breath-holding.