Syncope is a transient loss of consciousness due to transient global cerebral hypoperfusion characterised by rapid onset, short duration and complete recovery. It causes a lot of psychological trauma and limitation of activities of daily life, change of employment, restriction of driving etc. More than that, there is also an increase in mortality.
Vasovagal syncope is the commonest form. Carotid sinus hypersensitivity and orthostatic hypotension are important causes. Cardiac syncope can be due to arrhythmias or structural heart disease. Arrhythmias could be tachyarrhythmias or bradyarrhythmias. Sometimes the cause may remain undiagnosed inspite of full work up. Even this group has a small mortality risk. A number of conditions may also mimic syncope and needs exclusion in the work up.
A painstaking history is very important in the evaluation of syncope. Orthostatic hypotension has to be checked for. ECG, Holter and head up tilt test are important initial investigations. EP study and implantable loop recorder are the next set of investigations used in selected cases. An echocardiogram is needed to exclude structural heart disease.
Distinguishing a seizure from a syncope is quite important. Presence of an aura and prolonged tonic clonic movements are in favour of epilepsy. Similarly prolonged postictal state is also in favour of seizures. Neurological evaluation is needed when there is a possibility of seizures.