To the Editor:
Laugh-induced syncope has been described rarely in the literature. We present a case of a 29-year-old previously healthy man who had witnessed a coworker trip and hit his head on the sink at approximately 10 a.m. He subsequently went into a severe fit of uncontrollable laughter that involved leaning forward and crouching down, at which point he began to feel lightheaded and dizzy. He collapsed for 3 seconds with definite loss of consciousness and nonspecific arm twitching. He regained consciousness within those 3 seconds and was oriented properly and prepared to resume his work duties. Staff nearby who had witnessed the event immediately found his blood pressure to be 109/60 mm Hg with a heart rate of 96 beats/min. He was sent to the emergency department, and electrolyte, blood glucose, complete blood count, electrocardiogram, and echocardiogram testing results were normal. The tilt-table testing result was positive for neurocardiogenic syncope.
This is the third described case of laughter-induced syncope. The first case, in 1997, was a 62-year-old patient who had multiple episodes of syncope while laughing and watching Seinfeld on television.
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This clinical syndrome was thereby given the eponym of “Seinfeld syncope.” However, this patient had significant cardiovascular disease, including hypertension, prior coronary artery bypass grafting, and carotid disease. A second case was reported in 2005 in a healthy 32-year-old barber who heard a very funny story from a client.2
However, this patient had no demonstrable cardiovascular disease and normal laboratory results, similar to our patient.Laughter-induced syncope is similar to other causes of vasovagal syncope, such as cough, micturition, defecation, and Valsalva-induced syncope. There is an increase in intrathoracic pressure that causes an exaggerated response of the autonomic nervous system. Increased parasympathetic stimulation coupled with decreased sympathetic tone result in a decrease in heart rate, blood pressure, and cardiac output, which in turn causes global hypoperfusion and a transient decrease in cerebral hypoperfusion. Symptoms usually improve in a matter of seconds.
Vagally mediated syncope is a benign diagnosis. Most patients have decreased symptoms over time.
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This may be associated to pharmacologic treatment or improved recognition of prodromal symptoms and lifestyle modifications.Conservative treatment of vagally mediated syncope involves recognition of prodromal and maneuvers to abort attacks. Avoidance of precipitating factors, such as prolonged standing, rapid postural changes, and excessive alcohol intake, should be emphasized. Liberalization of salt and fluid intake coupled with compression stockings also decrease events. Discontinuation of vasodilators also may decrease episodes of syncope.
Pharmacologic treatment of vagally mediated syncope primarily involves initiation of beta-blockers. Their primary effect is in the reduction of myocardial contractility, which prevents the stimulation of the C fibers in the heart and the Bezold-Jarisch–type reflex that occurs. Beta-blockers also may decrease circulating catecholamines that are found in patients who develop syncope.
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Laughter-induced syncope or vagally mediated syncope is a benign disorder. Conservative therapy, including patient education, discontinuation of potentially offending medications, and treatment with beta-blockers, is the preferred initial therapeutic intervention.
References
- Seinfeld syncope.Cathet Cardiovasc Diagn. 1997; 42: 242
- Shear hilarity leading to laugh syncope in a healthy man.JAMA. 2005; 293: 2863-2864
- A controlled trial of acute and long-term medical therapy in tilt-induced neurally mediated syncope.Am J Cardiol. 1992; 70: 339-342
- Circulatory and catecholamine changes during head-up tilt testing in neurocardiogenic (vasovagal) syncope.Am J Cardiol. 1994; 73: 33-37
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© 2007 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
