ABSTRACT
Syncope Syncope is defined as a transient loss of consciousness with loss of postural tone. It becomes more common with advancing age and has many causes. Although the cause of the syncopal spell itself is usually benign, several serious consequences can result from the fall, including bone fracture and subdural hematoma. Regardless of the cause of syncope, the underlying mechanism is inadequate cerebral blood perfusion. It has been estimated that as many as one-third of syncope cases have a cardiac cause. These include valvular heart disease (aortic stenosis, mitral regurgitation, and mitral stenosis), hypertrophic cardiomyopathy, myocardial infarction, or cardiac arrhythmias (tachyarrhythmias or bradyarrhythmias). An orthostatic decrease in blood pressure is also common in the elderly because of changes in baroreceptor function. In addition, several disease states can be associated with orthostatic hypotension, including peripheral neuropathy, Parkinson disease, and Shy-Drager syndrome. Also, various medications can produce hypotension, including antihypertensive agents, tricyclic antidepressants, neuroleptics, and diuretics. Although vasovagal syncope is more common in younger persons, it can occur in the elderly. Carotid sinus hypersensitivity, an exaggerated hypotensive reflex that occurs in response to carotid sinus massage, also can cause syncope. Other exaggerated cardiovascular reflexes that can result in syncope include micturition, defecation, and coughing. Seizures, hypoxemia (pulmonary embolism or respiratory failure), severe hypoglycemia, and anemia also can produce syncope.
