Causes of Dizziness and Blackout

Syncope or Fainting is defined as “partial or complete loss of
consciousness with interruption of awareness of oneself and ones
surroundings”. When the loss of consciousness is temporary and the
person recovers spontaneously, it is referred to as syncope or, in non-
medical terms as fainting.

Syncope or fainting, results from a temporary reduction in the blood
flow and insufficient oxygen supply to the brain. When this occurs, the
individual may experience lightheadedness, a “blackout” episode or
loss of consciousness.

The reduction in blood supply to the brain can be caused by both
heart-related conditions as well as other conditions that do not affect
the heart. Syncope may be associated with a sudden fall in blood
pressure, a decrease in heart rate or changes in the blood volume or
distribution.

Causes of Syncope (Blackout)

1. Orthostatic Hypotension
Orthostatic hypotension is an abnormal change in blood pressure and
heart rate associated with an illness. Orthostatic (upright posture of
the body) hypotension (less + tension=pressure) refers to the fall in
blood pressure when an individual stands and the blood settles in the
legs.
Normally, an individual that stands up after sitting or lying down, will
not experience any discomfort as the body works to adjust to the
change in position. During this process, the body will push blood
upwards to supply the brain with oxygen.
If sufficient amount of blood is not supplied, the blood pressure will
lower and cause the individual to feel lightheaded or they may faint.
There is also postural hypotension which occurs when the blood
pressure drops suddenly because of a quick change in position, such
as from lying down to standing.

2. Dehydration
Dehydration results when the body suffers from inadequate water
levels, either by loss or reduction. Persons who are dehydrated will
have a decrease in their blood volume.
Normally the body regulates the amount of blood that is pumped by
the heart; if there is an inadequate amount of fluid in the intra-vascular
space, the body then increases the heart beat to maintain the blood
pressure.
The situation worsens as the dehydration becomes more severe and
will lead to syncope as the body’s organs receive less blood.

3. Environmental or Situational Causes
Neurological triggers such as intense levels of emotional
stress, anxiety, fear, pain, panic, hyperventilation and
hunger, alcohol and drug abuse can also lead to fainting.

4. Other Non-cardiac Causes
Diseases that affect the nervous system such as diabetes
or Parkinson’s disease. This is more frequent in older
people when poor tone of the nerves in the legs draws
blood into the legs from the brain.
Blood pressure medications which may lower the blood
pressure.
Neurological conditions such as migraines, seizure and
stroke.

4. Cardiac Related Causes
Abnormal heart rhythms where the heart rate is too low or fast.
Aortic stenosis – valvular heart disease caused by an incomplete opening of the aortic valve.
Pulmonic valve stenosis – valvular disease where blood outflow from the heart’s right ventricle is obstructed by the pulmonic valve.
Pulmonary artery hypertension – high blood pressure in the arteries supplying blood to the lungs.
Aortic dissection – tear in the aorta’s lining.
Cardiomyopathy – severe disease where the heart muscle
become inflamed.

© http://naijagym.blogspot.in/2015/04/what-causes-dizziness-and-blackout.html?m=1