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).