Reflex syncope occurs in response to a trigger due to dysfunction of the heart rate and blood pressure regulating mechanism. When heart rate slows, blood pressure drops, and the resulting lack of blood to the brain causes fainting.[7]
Vasovagal syncope[edit] => Typical triggers include:
Prolonged standing[5]&Emotional stress[5]&Pain[5]&The sight of blood[5]&Time varying magnetic field[8] (i.e. transcranial magnetic stimulation
Situational syncope[edit] => After or during urination (micturition syncope)[2]&Straining, such as to have a bowel movement[2]&Coughing[2]&Swallowing[2]&Lifting a heavy weight[2
Carotid sinus syncope[edit] => Pressing upon a certain spot in the neck.[5] This may happen when wearing a tight collar, shaving, or turning the head.[5]
In addition to the mechanism described above, a number of other medical conditions may cause syncope. Making the correct diagnosis for loss of consciousness is difficult. The core of the diagnosis of vasovagal syncope rests upon a clear description of a typical pattern of triggers, symptoms, and time course.
It is pertinent to differentiate lightheadedness, seizures, vertigo, and low blood sugar as other causes.
In people with recurrent vasovagal syncope, diagnostic accuracy can often be improved with one of the following diagnostic tests:
A tilt table test (results should be interpreted in the context of patients' clinical presentations and with an understanding of the sensitivity and specificity of the test)[11]&Implantation of an insertable loop recorder&A Holter monitor or event monitor&An echocardiogram&An electrophysiology stud
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. Fainting occurs with a loss of oxygen to the brain.[6]
The autonomic nervous system's physiological 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 hour