Syncope may also be associated with a short episode of muscle twitching. It is recommended that presyncope be treated the same as syncope. Causes range from non-serious to types of syncope pdf fatal.
The final type of syncope is due to a drop in blood pressure from standing up. Treatment depends on the underlying cause. Syncope affects about three to six out of every thousand people each year. It is more common in older people and females. It is the reason for one to three percent of visits to emergency departments and admissions to hospital. Up to half of women over the age of 80 and a third of medical students describe at least one event at some point in their life.
The risk of a poor outcome, however, depends very much on the underlying cause. The central ischaemic response is triggered by an inadequate supply of oxygenated blood in the brain. These processes cause the typical symptoms of fainting: pale skin, rapid breathing, nausea and weakness of the limbs, particularly of the legs. If the ischaemia is intense or prolonged, limb weakness progresses to collapse. An individual with very little skin pigmentation may appear to have all color drained from his or her face at the onset of an episode. This effect combined with the following collapse can make a strong and dramatic impression on bystanders. The weakness of the legs causes most sufferers to sit or lie down if there is time to do so.
This may avert a complete collapse, but whether the sufferer sits down or falls down, the result of an ischaemic episode is a posture in which less blood pressure is required to achieve adequate blood flow. It is unclear whether this is a mechanism evolved in response to the circulatory difficulties of human bipedalism or merely a serendipitous result of a pre-existing circulatory response . Arterial disease in the upper spinal cord, or lower brain, causes syncope if there is a reduction in blood supply, which may occur with extending the neck or after drugs to lower blood pressure. Isolated episodes of loss of consciousness, unheralded by any warning symptoms for more than a few moments. The subject is invariably upright. Recurrent syncope with complex associated symptoms.
The subject is usually but not always upright. The tilt-table test, if performed, is generally positive. A pattern of background factors contributes to the attacks. There is typically an unsuspected relatively low blood volume, for instance, from taking a low-salt diet in the absence of any salt-retaining tendency. Heat causes vaso-dilation and worsens the effect of the relatively insufficient blood volume. The next stage is the adrenergic response. The abnormality lies in this excessive vagal response.