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Chapter 021. Syncope (Part 3)

Situational Syncope A variety of activities, including cough, deglutition, micturition, and defecation, are associated with syncope in susceptible individuals. Like neurocardiogenic syncope, these syndromes may involve a cardioinhibitory response, a vasodepressor response, or both. Cough, micturition, and defecation are associated with maneuvers (such as Valsalva's, straining, and coughing) that may contribute to hypotension and syncope by decreasing venous return. Increased intracranial pressure secondary to the increased intrathoracic pressure may also contribute by decreasing cerebral blood flow.Cough syncope typically occurs in men with chronic bronchitis or chronic obstructive lung disease during or after prolonged coughing fits. . | Chapter 021. Syncope Part 3 Situational Syncope A variety of activities including cough deglutition micturition and defecation are associated with syncope in susceptible individuals. Like neurocardiogenic syncope these syndromes may involve a cardioinhibitory response a vasodepressor response or both. Cough micturition and defecation are associated with maneuvers such as Valsalva s straining and coughing that may contribute to hypotension and syncope by decreasing venous return. Increased intracranial pressure secondary to the increased intrathoracic pressure may also contribute by decreasing cerebral blood flow.Cough syncope typically occurs in men with chronic bronchitis or chronic obstructive lung disease during or after prolonged coughing fits. Micturition syncope occurs predominantly in middle-aged and older men particularly those with prostatic hypertrophy and obstruction of the bladder neck loss of consciousness usually occurs at night during or immediately after voiding. Deglutition syncope and defecation syncope occur in men and women. Deglutition syncope may be associated with esophageal disorders particularly esophageal spasm. In some individuals particular foods and carbonated or cold beverages initiate episodes by activating esophageal sensory receptors that trigger reflex sinus bradycardia or atrioventricular AV block. Defecation syncope is probably secondary to Valsalva s maneuver in older individuals with constipation. Carotid Sinus Hypersensitivity Syncope due to carotid sinus hypersensitivity is precipitated by pressure on the carotid sinus baroreceptors which are located just cephalad to the bifurcation of the common carotid artery. This typically occurs in the setting of shaving a tight collar or turning the head to one side. Carotid sinus hypersensitivity occurs predominantly in men 50 years old. Activation of carotid sinus baroreceptors gives rise to impulses carried via the nerve of Hering a branch of the glossopharyngeal nerve to the medulla