Cough Syncope
Cough syncope is a transient loss of consciousness with facial congestion and cyanosis; it typically occurs within seconds of a coughing attack, followed by rapid recovery. Cough syncope may originally mimic epilepsy. It was previously considered a form of epilepsy, called ”laryngeal epilepsy” because of the jerky movements associated with it. However, many studies showed normal electrical activity of the brain during the episodes. It typically occurs in middle-aged and older male smokers, overweight or muscularly built with a history of chronic obstructive pulmonary disease. These individuals are more prone to produce very high intrathoracic pressure associated with cough-induced syncope and fainting (53). Because it is mainly a condition in adults, cough syncope has rarely been reported in children, especially in children younger than 10 years of age (54). The exact mechanism of cough syncope is controversial. Coughing markedly increases intrathoracic pressure and decreases cardiac output, thereby decreasing systemic blood pressure and causing cerebral hypoperfusion. At the same time, cerebrospinal fluid pressure increases, resulting in decreased cerebral perfusion; or there is a cerebral concussion-like effect due to the rapid rise in cerebrospinal fluid pressure. Another theory is that the cough triggers neurally mediated reflex vasodepressor bradycardia. Elimination of the cough eliminates the resulting syncopal episodes (55).
During the syncopal episode, the patient may have fixed upward deviation of the eyes, which should not be confused with epilepsy. The EEG shows transient slowing during the syncope but no seizure-like discharges. It is always associated with a coughing fit. The face becomes plethoric rather than cyanotic, and the entire episode lasts less than a minute. Syncope is never preceded by aura and is very rarely followed by postictal confusion/headache. Cough syncope usually occurs at night in the prone position, whereas epilepsy can occur in any position (56). Cough syncope is associated with a high incidence of pulmonary, cardiac, and neurologic disorders. Numerous CNS disorders have been associated with cough syncope, including cerebral tumors (meningioma, glioblastoma), herniation of cerebellar tonsils (type-1 Arnold-Chiari malformation), hydrocephalus, arterial occlusive disease of the carotid and vertebral arteries, basilar invagination, autosomal dominant hereditary sensory neuropathy, and medullary infarction (57).