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The term syncope (Greek: synkope) literally means a “cessation,” a “cutting short,” or “pause.” Medically, it refers to an episodic loss of consciousness and postural tone and an inability to stand because of a diminished flow of blood to the brain. It is synonymous in everyday language with fainting. Feeling faint and a feeling of faintness are also commonly used terms to describe the loss of strength and other symptoms that characterize the impending or incomplete fainting spell. This latter state is referred to as presyncope. Relatively abrupt onset, brief duration, and spontaneous and complete recovery not requiring specific resuscitative measures are other typical features.

Faintness and syncope are among the most common of all medical phenomena. Practically every adult has experienced some presyncopal symptoms if not a fully developed syncopal attack or has observed such attacks in others. Description of these symptoms, as with other predominantly subjective states, is often ambiguous. The patient may refer to the experience as light-headedness, giddiness, dizziness, a “drunk feeling,” a weak spell, or, if consciousness was lost, a “blackout.” Careful questioning may be necessary to ascertain the exact meaning the patient has given to these words. In many instances the nature of the symptoms is clarified by the fact that they include a sensation of faintness and then a momentary loss of consciousness, which is easily recognized as a faint, or syncope. This sequence also informs us that under certain conditions any difference between faintness and syncope is only one of degree. These symptoms must be clearly set apart from certain types of epilepsy, the other major cause of episodic unconsciousness, and from disorders such as cataplexy, transient ischemic attacks (TIAs), “drop attacks,” and vertigo, which are also characterized by episodic attacks of generalized weakness or inability to stand upright, but not by a loss of consciousness.

The clinical manifestations of fainting attacks vary to some extent, depending on their mechanisms and the settings in which they occur. The most common type of faint—namely, vasodepressor or vasovagal syncope, defined more precisely further on, conforms more or less to the following pattern. The patient is usually in the upright position at the beginning of the attack, either sitting or standing. Certain subjective symptoms, the prodrome, mark the onset of the faint. The person feels queasy, is assailed by a sense of giddiness and apprehension, may sway, and sometimes develops a headache. What is most noticeable at the beginning of the attack is pallor or an ashen-gray color of the face; often the face and body become bathed in cool perspiration. Salivation, epigastric distress, nausea, and sometimes vomiting may accompany these symptoms, and the patient tries to suppress them by yawning, sighing, or breathing deeply. Vision may dim or close in concentrically, the ears may ring, and it may be impossible to think clearly (“grayout”). This serves to introduce the common faint that is known to all physicians and most laypersons; a ...

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