Vasovagal syncope

Reflex syncope is a brief loss of consciousness due to a neurologically induced drop in blood pressure. Before the person passes out there may be sweating, a decreased ability to see, or ringing in the ears. Occasionally the person may twitch when unconscious. Complications may include injury from a fall. Reflex syncope is divided into three types: vasovagal, situational, and carotid sinus. Vasovagal syncope is typically triggered by seeing blood, pain, emotional stress, or prolonged standing. Situational syncope is often triggered by urination, swallowing, or coughing. Carotid sinus syncope is due to pressure on the carotid sinus in the neck. The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels resulting in low blood pressure and therefore not enough blood flow to the brain. Diagnosis is based on symptoms after ruling out other possible causes. Recovery happens without specific treatment. Prevention involves avoiding the triggers. Drinking sufficient fluids, salt, and exercise may also be useful. If this is not sufficient for vasovagal syncope, medications like midodrine or fludrocortisone may be tried. Occasionally a cardiac pacemaker may be used. Reflex syncope affects at least 1 per 1,000 people a year. It is the most common type of syncope, making up more than 50% of all cases. Episodes of vasovagal syncope are typically recurrent and usually occur when the predisposed person is exposed to a specific trigger. Before 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, an uncomfortable feeling in the heart, fuzzy thoughts, confusion, a slight inability to speak or 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 may become more intense over several seconds to several minutes before the loss of consciousness (if it is lost). Onset usually occurs when a person is sitting up or standing. When people lose consciousness, 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. The autonomic nervous system's physiological state (see below) leading to loss of consciousness may persist for several minutes, so Reflex syncope occurs in response to a trigger due to dysfunction of the heart rate and blood pressure regulating mechanism. When heart rate slows or blood pressure drops, the resulting lack of blood to the brain causes fainting.