Have you witnessed persons having episodes of fainting and loss of consciousness? Are there episodes of decreased alertness?
When a human being loses contact with surroundings, is not aware of what is happening to him/her then it is called fainting or loss of consciousness. This happens when brain does not function either because of lack of supply of energy through overall decrease in blood supply or there is an excessive burst of electrical discharges in the brain cells when they lose their to function despite availability energy
When there is a global lack of cerebral energy due to rapid decrease in brain’s blood supply then it is called Syncope/Common faint. Common faint occurs when due to various causes there is an overall rapid fall of total blood supply to brain takes place as opposed to a localized long-lasting but acute suspension of blood supply due to blockage of an artery of brain by a clot or rupture/leakage of a blood vessel of brain which is called Stroke.
Many a times the common faint occurs because of arteries of brain getting widened known as dilatation. Such a change in arterial calibre usually occurs when there is acute painful distressing sight or a strong unpleasant smell or when the person is sweating and standing for a long time as in school prayer or a crowded place. In some individuals with irregular heartbeats or very slow heart rate also the supply/ flow of blood to brain diminishes causing Syncope. This also produces fainting.
Similarly, when there is an excessive fluid loss from body or a fall in blood pressure on standing occurs similar reduction in brain blood circulation takes place causing Syncope. Such a posture related fall in blood pressure is called orthostatic hypotension. Similarly, excessive dilatation of body blood vessels occurs in certain situations like during passing of urine (micturition syncope) or passing stools called ( defecation syncope) or fainting on coughing called cough syncope.
The majority of cases of syncope are short-lasting self-correcting and can be easily treated and they can be diagnosed by good clinical neurological examination. The clinical hallmark of syncope is that all body parts become loose, jaw drops, eyes closed, in general there is no stiffness in any part of body as opposed to epilepsy or seizures which also produce loss of consciousness. The investigation include EEG, CT/MRI brain, ECG, echocardiography, brain count, blood sugar, and electrolytes.