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A vagal episode or vasovagal response or vasovagal attack (also called neurocardiogenic syncope) is a malaise mediated by the vagus nerve. When it leads to fainting, also known as a "syncope", it is called a vasovagal syncope, which is the most common type of fainting. Vasovagal syncope is most commonly found in adolescents and in younger adults. There are different syncope syndromes which all fall under the umbrella of vasovagal syncope. The common element among these conditions is the central mechanism which may lead to the loss of consciousness. The differences among them are in the factors that trigger this mechanism. ==Signs and symptoms== Episodes of vasovagal response are typically recurrent and usually occur when the predisposed person is exposed to a specific trigger. Prior to losing consciousness, the individual frequently experiences early signs or symptoms such as lightheadedness, nausea, the feeling of being extremely hot or cold (accompanied by sweating), ringing in the ears (tinnitus), an uncomfortable feeling in the heart, fuzzy thoughts, confusion, a slight inability to speak/form words (sometimes combined with mild stuttering), weakness and visual disturbances such as lights seeming too bright, fuzzy or tunnel vision, black cloud-like spots in vision, and a feeling of nervousness can occur as well. The symptoms last for a few seconds before the loss of consciousness (if it is lost), which typically happens when the person is sitting up or standing. When sufferers pass out, they fall down (unless prevented from doing so) and, when in this position, effective blood flow to the brain is immediately restored, allowing the person to regain consciousness. If the person does not fall into a fully flat, supine position, and the head remains elevated above the trunk, a state similar to a seizure may result from the blood's inability to return quickly to the brain, and the neurons in the body will fire off and generally cause muscles to twitch very slightly but mostly remain very tense. Fainting occurs with a loss of oxygen to the brain.〔Ajamian, Paul C. "If patient faints, be laid back: what do you do when a patient passes out in your office? Lay the patient back to restore blood and oxygen to the brain." Review of Optometry 143.7 (July 15, 2006): 85(2). Nursing Resource Center. Gale. California State Univ East Bay. 13 Mar. 2013〕 The autonomic nervous system's physiologic state (see below) leading to loss of consciousness may persist for several minutes, so * If sufferers try to sit or stand when they wake up, they may pass out again * The person may be nauseated, pale, and sweaty for several minutes or hours 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Vasovagal response」の詳細全文を読む スポンサード リンク
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