Syncope is a clinical syndrome, a transient, self-limiting loss of consciousness with a rapid onset followed by rapid and spontaneous full recovery, the underlying pathogenesis is transient cerebral hypoperfusion, usually without any signs of loss of consciousness, sometimes with some clinical aura (e.g., mild headache, nausea, sweating, weakness and blurred vision). The exact duration is difficult to determine and usually does not exceed 20 seconds Wang Aihua, Department of Neurology, Shandong Qianfo Mountain Hospital
I. Etiological classification
1. Neurally mediated reflex syncope syndrome
– Vascular vagal syncope
– Carotid sinus syncope
– Situational syncope
– Acute hemorrhage
– Coughing, sneezing
– Gastrointestinal irritation (swallowing, visceral pain)
– Urination (after urination)
– After activity
– Other (e.g., after blowing horn, lifting weights, eating)
– Glossopharyngeal and trigeminal neuralgia
2. Upright hypotensive syncope
– Autonomic dysfunction
– Primary autonomic dysfunction syndrome (e.g., simple autonomic dysfunction, multisystem atrophy, Parkinson’s disease with autonomic dysfunction)
– Secondary autonomic dysfunction syndromes (e.g., diabetic neuropathy, amyloid neuropathy)
– Drugs or alcohol
– Decreased blood volume
– Bleeding, diarrhea, Addison’s disease
3. Arrhythmias as a primary cause
– Sinus node dysfunction (including fast-slow syndrome)
– Diseases of the atrioventricular conduction system
– Paroxysmal supraventricular and ventricular tachycardia
– Genetic syndromes (e.g., long QT interval syndrome, Brugada syndrome)
– Implantation device (pacemaker, ICD) disorders, drug arrhythmias
4. Organic heart disease or cardiopulmonary disease
– Heart valve disease
– Acute myocardial infarction / myocardial ischemia
– Obstructive cardiomyopathy
– Atrial mucinous tumor
– Acute aortic dissection
– Pericardial disease / pericardial tamponade
– Pulmonary artery embolism / pulmonary hypertension
5. Cerebrovascular disease
– Vascular steal syndrome
III. Diagnosis
1. vasovagal or vasopressor syncope
– Mostly occurs in people with weak body type, more in upright position, more in young people than in old people
– There are often sudden and unexpected pain, fear or bad visual, auditory and olfactory stimuli, hot and muggy weather, foul air and other triggers, especially standing for too long or exercise
– Loss of consciousness is often preceded by pallor, sweating, epigastric discomfort with nausea, which can be avoided by lying down immediately. Lie down during seizure, consciousness can be recovered quickly
– Pallor, nausea, weakness, and sweating may persist for some time. If you stand up or sit up in a hurry, you may have another attack.
– In typical cases, loss of consciousness does not exceed 1 minute
2. Upright hypotensive syncope
2.1. Clinical manifestations of upright hypotensive syncope
– Occurs only in the upright position, especially when changing from the prone to the standing position
– No obvious cause.
– Mostly without antecedent symptoms.
– significant decrease in blood pressure without change in heart rate during the onset.
– Idiopathic upright syncope is mostly seen in middle-aged and elderly people, which is caused by vegetative nerve dysfunction, and also impotence, no sweating, and bladder rectal dysfunction
2.2. Diagnostic methods of upright hypotensive syncope
– Detection method of upright hypotension.
– Lie flat for 5 minutes, then measure blood pressure in the upright position for 1 minute or 3 minutes and longer
– If the blood pressure remains lower at 3 minutes, it is positive if the patient is unable to maintain the standing position during this period
– The lowest systolic blood pressure should be recorded during the standing position. A decrease in systolic blood pressure ≥20 mmHg or a decrease in systolic blood pressure to ≤90 mmHg, regardless of symptoms, is considered upright hypotension
3. Carotid sinus allergic syncope
– Most often occurs in middle-aged or older individuals
– Syncope attacks are induced by pressure on the neck (e.g., tumor, hard collar, trimmed face, etc.) or sudden rotation of the neck to compress the carotid sinus
– Pressing on the carotid sinus can induce syncopal attacks. Slow heart rate and low blood pressure during the attack, but without prodromal symptoms such as nausea and pallor.
– Some patients have allergic reflex lesions around the carotid sinus, such as enlarged lymph nodes in the neck, tumors or scar tissue compression of thyroid surgery.
4. Urinary syncope
– Most often occurs in young and strong men
– When waking up at night after sleep to urinate or after urination
– There is no antecedent symptom before the onset, or there is only transient dizziness, blurred vision and weakness of lower limbs, and the person wakes up on his own after fainting for about 1-2 min.
– The mechanism may be: strong vagal reflex caused by bladder contraction, resulting in cardiac depression and blood pressure drop; reflexive peripheral vasodilatation caused by changing from prone to standing position; temporary cerebral hypoperfusion caused by sudden decrease of abdominal pressure during urination
5. Cough syncope
– Seizure during violent coughing
– Commonly seen in patients with chronic obstructive pulmonary disease
– The mechanism may be a rise in intrathoracic pressure during coughing, which prevents venous return to the heart and reduces cardiac output
– Or coughing may reflexively cause an increase in cranial pressure, affecting cerebral blood circulation and causing cerebral ischemia.
6. Swallowing syncope
– It is seen in patients with esophageal tumor, diverticulum, spasm, pharyngeal or mediastinal diseases
– Painful or difficult swallowing occurs when swallowing, and the dilatation of the esophagus provokes the vagus nerve causing bradycardia, conduction block and other arrhythmias leading to syncope
– The onset of syncope is not related to body position and there are no prodromal symptoms.
7. Arrhythmia-related syncope (omitted)
8. Organic heart disease or cardiopulmonary disease syncope (omitted)