The Classification and Pathophysiology of Cough Syncope

Mr. KH is a 53 year old gentleman who was admitted to A & E after a minor traffic accident. He sustained no traumatic injuries, and his main concern was the event preceding accident, which was a complete loss of consciousness. He had never experienced such loss of consciousness before, and he was not fatigued nor confused upon wakening. He had complete memory of events prior to the syncope, and presented with no chest pain, nausea, palpitations, nor sweating pre and post syncope. The only precipitating factor was excessive cough, which had onset 5 weeks ago. Mr. KH has significant cardiac history of 2 Percutaneous Transluminal Coronary Angioplasty in 1991 and 1994, and had suffered Myocardial Infarction in 1999, after which a stent was placed. The review of systems did not reveal any neurological abnormalities and history of epilepsy, and physical examination showed regular strong pulse at 60 bpm and blood pressure of 150/90. ECG examination failed to show AV block, arrhythmia, and long Q-T interval. The differential diagnosis of cough syncope was made based on patient’s history and elimination of other probable causes, including: cerebrovascular causes such as stroke, tumor, or intracranial haemorrhage, and cardiovascular causes such as arrhythmia or myocardial infarction. Mr. KH 's presentation during the attack was also consistent with criteria and symptoms of situational syncope, specifically cough syncope.
Syncope is classified according to its suspected pathophysiology as follows:
 Neurally-mediated reflex syncopal syndrome referring to a reflex that, when triggered, gives rise to vasodilation and bradykardia (1)
 Orthostatic syncope occurring when the autonomic nervous system is incapacitated resulting in a failure of vasoconstrictor mechanisms and thereby in orthostatic hypotension (1)
 Cardiac arrhythmias causing a decrease in cardiac output (1)
 Structural heart disease causing syncope when circulatory demands outweigh the impaired

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