Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Fainting, "blacking out," or syncope is the temporary
loss of consciousness followed by the return to full wakefulness. This loss of
consciousness may be accompanied by loss of muscle tone that can result in falling or slumping over.
To better understand why fainting can occur; it is helpful to explain why
somebody is awake.
The brain has multiple parts, including two hemispheres, the cerebellum, and
the brain stem. The brain
requires blood flow to provide oxygen and glucose
(sugar) to its cells to sustain life. For the body to be awake, an area known as
the reticular activating system located in the brain stem needs to be turned on,
and at least one brain hemisphere needs to be functioning. For fainting or syncope to occur,
either the reticular activating system needs to lose its blood supply, or both
hemispheres of the brain need to be deprived of blood, oxygen, or glucose. If
blood sugar levels are normal blood flow must be briefly disrupted to
the whole brain or to the reticular activating system.
Fainting is not caused by head trauma, since loss of
consciousness after a head injury is considered a concussion. However, fainting can cause injury if
the person falls and hurts themselves, or if the faint occurs while
participating in an activity like driving a car.
Fainting is differentiated from
which patients may also lose consciousness.
Vasovagal syncope is a common cause of fainting. The vagus nerve is overstimulated and causes the body's blood vessels to dilate and the heart to slow down. This anti-adrenaline effect decreases the ability of the heart to pump blood upward to the brain against gravity. Without blood flow, the brain turns off. In Victorian England, when this happened because young ladies' sensibilities were easily offended, this was called a swoon.
The tilt-table test is a simple, inexpensive, and informative test that can help identify the causes of fainting. As its name implies, the tilt table test involves placing a patient on a table with a foot-su"...