Introduction: We have heard of people who
had Stroke. It happens suddenly. The person
may fall and becomes paralyzed almost immediately, unable to move a part of the
body, usually the arm and leg of one side of the body. Speech may be slurred
and the patient may also be unconscious and require immediate hospital
attention. Stroke is a common word used to describe the damage that happens in
the brain of the person who suffers it. The brain has three main parts, namely,
the cerebrum, the cerebellum, and the brain stem. These three are further
divided into smaller parts according to their nature and work. These various
parts of the brain control different functions in the body. For example, there
is a part that controls breathing; another part controls speech; another,
movement of a leg; another, of an arm, and so forth. If the part of the brain
that controls speech is affected in Stroke,
the person will have difficulty talking. Same with movement of an arm or leg,
etc.
How does blood
get to the brain? To understand Stroke, we
have to know how blood gets to the brain.
Every part of the body receives blood which flows
round the body. The volume of blood that gets to any organ in the body depends
on its need and work. Though the brain is small in size compared to some other
organs in the body, it receives more blood than they do. When a person is
resting, about 16% of the total volume of blood circulating in the body in a
minute (Cardiac output) gets to the brain. This is the third largest blood
supply to any single organ in the body, next only to the liver, which receives
about 27% of the cardiac output at rest, and the kidneys which receive about
23%.
Blood contains oxygen, the main air we breathe in. This
is transported through the arteries to organs. As the arteries get closer the
organ they divide into smaller branches called arterioles. As the arterioles
penetrate the tissues of the organ they divide further into even smaller units
called capillaries. Capillaries connect with themselves to form a network
(often called capillary bed) inside the tissues of the organ. Here, they
deliver oxygen and nutrients to the tissue, and from there a similar network of
vessels take off to leave the organ as venules and veins. Carbon dioxide is
removed from the tissue through the veins to the lungs where it is breathed
out, while other metabolic wastes are taken to the kidneys from where they are
discharged in the urine.
Why does
Stroke occur?
Stroke occurs when one or more of
the following happens in the path blood supply to the brain.
1.
Blood clots and blocks any of the vessels taking blood to the brain.
This is called thrombosis. A blood
clot in a blood vessel is called a thrombus. It can occur in any vessel of the
body including the arteries of the leg.
2.
A thrombus is carried in the general blood circulation from where it
was formed to lodge in an artery of the brain (cerebral artery), which it then
blocks. Other substances that can be carried in the blood to block a cerebral
artery include fatty deposits in the wall of an artery and air. Any substance
carried in the blood from one point to lodge in another is called an embolus,
and the process of conveying it, embolism.
So, if, for example, a thrombus forms elsewhere in the body and is then flushed
out by the circulating blood from where it formed and carried in the general
circulation to lodge in a cerebral artery, it is a thromboembolic phenomenon.
Thrombotic or thromboembolic
stroke does not usually kill the patient. It rather causes impairment of
function, for example, weakness of an arm or leg, inability to lift them,
incoherent speech, a turning of a part of the body to one side, etc.
3.
A cerebral artery suddenly burst from high pressure inside it, causing
bleeding into brain tissue. In this case the leaked blood in the non-expansive
skull will exert pressure on brain tissue and affect its function. Bleeding is
also known as haemorrhage, so this
type of stroke is known as haemorrhagic stroke. It is more dangerous than
thrombotic or thromboembolic stroke. Patients who suffer haemorrhagic stroke
most often present with sudden, severe headache, usually at the back of the
head. This may be followed by vomiting and loss of consciousness in quick
succession. About half the number of those who suffer haemorrhagic stroke never
come out of coma, and usually die within a month.
Risk factors
in Stroke:
By this is meant those factors that predispose a
person to having Stroke. Why may a person be considered more likely to have
Stroke than another? The following are risk factors:
1.
Hypertension: This is increased pressure in the arteries for which, in most cases,
no cause can be found. This has sometimes been called Essential Hypertension.
At other times, causes may be found in the neurological (nervous) system or the
vascular system (arteries mainly) or the endocrine system (Hormonal effect) or
the renal system (the kidneys). An old mnemonic for causes of hypertension is NEVER, that is, Neurological, Essential,
Vascular, Endocrine, and Renal.
Increased pressure in the arteries may burst the smaller sized ones, spilling
blood into brain tissue and causing haemorrhagic stroke.
2.
Heart Disease: When pressure rises in the arteries beyond normal limits, it backfires
on the heart that pumps blood through the arteries at that high pressure. Thus
the heart would have to work extra to overcome the resistance posed against the
forward movement of blood. Over a period of time, this may cause the heart to
expand and increase its demand for oxygen and nutrients. If after a long time,
perhaps years, the ability of the heart to deliver blood with oxygen to tissues
(including brain tissue) is diminished, the tissues’ optimal performance is
equally compromised. Besides, emboli (plural of embolus) can arise from
infections of the heart and be transported to block a cerebral artery causing
cerebral infarction and stroke.
3.
Diabetes Mellitus: This is not just a disease but a syndrome, that is,
a disease process affecting many systems in the body. In the Cardiovascular
System (CVS, the system made up of the heart and blood vessels), the arteries
easily develop fatty deposits in their wall (atheroma). These fatty deposits can
flake off and be carried as an embolus to block a cerebral artery causing
stroke.
4.
High blood cholesterol: Cholesterol is the fatty product that forms
atheroma in arterial walls. This can happen with or without the person having
diabetes. It is primarily due to high intake of cholesterol yielding foods like
red meat, egg yolk, full cream milk, and saturated fats found in palm oil and
some other oils. With atheroma formation, the likelihood of cerebral embolism
and stroke is high.
5.
Obesity: A person is obese if their Body
Mass Index (BMI) is 30 mg/kg2 and above. It is a risk factor in
Stroke because most obese people also have hypertension and/or high blood
cholesterol, both of which could lead to Stroke.
6.
Sedentary lifestyle: This is a sit-down or lie-down most-of-the-time way
of life. It includes taking a vehicle to almost everywhere one goes (an
unwillingness to trek even short distances), not willing to get involved in
routine activities or exercises, while all the time taking one’s full
complement of food. This leads to obesity with attendant consequences.
7.
Others: We consider earlier factors mentioned as the major risk factors in
Stroke, especially hypertension. Other factors that may indirectly contribute
to Stroke are cigarette smoking, increased alcohol intake, use of oral
contraceptives, ageing, excess red blood cells which make the blood thicker and
sluggish in flow (as in people who never donate blood) and stress.
These factors are at some point interrelated. On may
lead to another.
Prevention of
Stroke:
Prevention, they say, is better than cure. To
prevent stroke on needs to do the following:
1.
Check your Blood Pressure
regularly.
Attend to it as deserving. See a doctor to guide you.
2.
Reduce your salt intake to near zero. You do not
need ‘table salt’. This is the one potent factor incriminated in hypertension.
Use salt sparingly.
3.
Do mild and graded
exercises.
See a doctor to examine you and advice on which exercises are good for you.
4.
Learn to relax. Do not overstress yourself.
Normal rest relieves the body of tension. But if you are confined to bed by
illness, then you need to do more exercises than relax because you are already
relaxing enough.
5.
Reduce weight if overweight. Maintain a
BMI of 19 – 24.9 kg/m2. See a doctor to guide you.
6.
Do not take medicines
indiscriminately. Many buy and use iron and mineral products, believing them to be for
health maintenance. This is not always true and some can actually be harmful.
Only use drugs prescribed for you by a medical doctor, especially when sick. Do
not patronize quacks. They can make your case worse.
7.
If on treatment for
hypertension, please be faithful to it and report to your doctor when the drugs finish.
8.
Regulate your diet. Take more water, fruits,
vegetable and vegetable products, sea foods like fish, fish oil, crabs,
periwinkles, etc. take less carbohydrates, animal proteins and fats.
9.
Possibly stop smoking and much
intake of alcohol.
No comments:
Post a Comment