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Stroke : Causes
Western Medicine Chinese Medicine

High blood pressure is a leading cause of stroke.

Other factors that make people more likely to suffer stroke are:

Atherosclerosisa condition where fatty deposits build up in and weaken arteries. If those deposits build up in the carotid arteries, the large arteries in the neck, the chances of stroke are very much increased because the risk of embolus is so great.
Having heart disease, especially atrial fibrillation (a condition where the upper chamber of the heart, the atrium, develops an irregular beat). This irregular beat makes the blood flow more slowly so that clots form on the walls of the atrium. Pieces of these clots break off and travel to the brain where they block blood vessels, causing strokes.
Being male
Taking oral contraceptive pills, which make the blood more likely to form clots.
Having blood disorders interfering with normal clotting.
Having high blood fat and/or blood cholesterol levels.

Click here to see causes of stroke from a TCM Perspective

In TCM theory, stroke is not just considered an illness of the brain. It affects the meridians, other organs and blood vessels as well. It is thought to be caused by internal and external influences that induce a build up of qi and blood and create a high pressure state, which ultimately leads to a stroke. This is similar to western medicine's understanding of high blood pressure being a risk factor for developing a stroke.

The mechanisms by which a stroke occurs and causes bodily damage are complicated. At least four external factors and six internal factors have been identified that contribute to this process. The external risk factors that contribute to the development of a stroke include the hypo- functioning or under functioning of the liver and kidney, improper diet and body overstrain, emotional disturbance, and aging and weak body constitution. These lead to further problems inside the body that upset its natural healthy balance. The six internal influences that contribute to a stroke are deficiency states such as yin deficiency and qi; deficiency an excess of fire (sometimes referred to as excessive heat) such as liver-fire and heart-fire; wind evils such as endogenous wind originating from inside the body and exogenous wind originating from outside the body; an accumulation of phlegm; stagnant qi flow and blood stasis. These six factors will interact with each other under certain conditions to bring forth diseases such as a stroke. The TCM mechanisms by which a stroke occurs are further detailed below.

How the under- functioning or hypo- function of the liver and kidney cause a stroke

A yin deficiency occurring from old age, hypo-function (under-function) of both the liver and kidney, or an excess of sexual activities can all lead to a gradual exhaustion of germ cells and blood. Germ cells are the sperm and egg cells. Germ cells and blood come from the same source in TCM. When germ cells decrease with age, production of blood declines. This leads to relative yang excess in the body, and causes wind evil to build up inside. Stroke will finally develop if the wind evils are not removed from the body.

When the kidney, which belongs to water of the five elements, fails to nourish the liver- a wood element - a liver-yang excess is produced that transforms into an internal wind evil. The wind evil is responsible for causing the stroke. Alternatively, stroke may be also caused by an insufficiency of liver-yin. This occurs when heat is produced due to the dryness of the blood. The heat makes the wind evil flow upwards in the body which affects the meridians and obstructs orifices (openings of the body). This in turn causes qi and blood flow to become stagnant which can cause a stroke.

How excess fire or heat causes a stroke The kidney belongs to the water of the five elements. When kidney yin is exhausted, it cannot restrict a build up of fire or heat in the body caused by mental stress, emotional disturbances or an extreme excess of heart-fire. Excess heat causes depression and confusion, and induces too much qi and blood to ascend to the brain, which leads to a stroke.

Accumulation of phlegm and dampness
Over consumption of food and drink leads to spleen malfunction. In TCM, the spleen is responsible for transforming food and drink into qi, and transporting it to the lungs where it can be distributed throughout the body to nourish it. When it malfunctions, an accumulation of dampness develops which leads to a build up of phlegm. When this phlegm cannot be removed, it transforms into heat and then an evil wind; all of which exert negative influences on the body and cause illness. The build up of phlegm, heat and wind all disturb the meridians and brain, which can lead to a stroke.

Alternatively, phlegm can accumulate when there is a liver-yang excess. It is produced when wind evils builds up in the liver and a person overworks or is unable to sleep at night. One of the liver's main functions is to support the flow of qi throughout the body, so a build up of wind evils accompanied by phlegm disturbs the meridians and causes the circulation of qi to stop. This results in unconsciousness, which is a serious symptom of a stroke.

How old age, body weakness and qi deficiency allow evil influences to invade the body and cause stroke

When a person experiences old age, a qi deficiency or has excessive thinking and fatigue, qi flow and blood circulation are damaged especially in the small collaterals of the meridians. Pathogens (any substance that causes an illness) take this opportunity to invade the body, which leads to further stagnation of qi and blood flow. This lack of normal qi and blood movement within the body causes a loss of nourishment to the tendons and muscles, which ultimately can lead to numbness of skin and muscles often seen with stroke.

A weak body constitution can cause a chronic accumulation of phlegm-dampness and allow exogenous pathogens (any substance originating from outside the body that causes an illness) like wind to invade the body. These wind and phlegm evils block the meridians and orifices (any body opening like the mouth) and lead to stroke symptoms such as hemiplegia (paralysis on one side of the body).