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During prolong coughing,intrathoracic intra-abdominal pressures are transmitted via the great veins to the intracranial compartment,causing transient elevated intracranial pressure.The resulting reduction of cerebral perfusion pressure may cause a critical impairment of cerebral blood flow(CBF).Obstructive airway disease seems to be a prerequisite to build up the intrathoracic and intracranial pressures to a degree sufficient to compromise CBF and cause cough syncope.Using transcranial Doppler sonography(TCD)monitoring of middle cerebral artery flow velocities,we studied three patients with cough syncope.During coughing they showed a transient cerebral circulatory arrest which coincided with loss of consciousness in the two patients who fainted during TCD monitoring.EEG showed slowing,heart rate increased,and systemic arterial BP in one patient was preserved during the syncope.Our findings support the hypothesis that a critical reduction of CBF causes cough syncope. |
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