Cerebral circulation refers to the way blood flows, or circulates, in the brain. Cerebral circulation is important for healthy brain function. This is because your brain requires the exchange of oxygen and nutrients to function properly. During cerebral circulation, blood vessels deliver oxygen and glucose to various areas in the brain. When this circulation is impaired, many conditions and disabilities related to neurological function can result.
There are four main arteries that supply the brain with blood: the left and right internal carotid and the left and right vertebral arteries. These arteries branch off into other smaller blood vessels. These nourish different sections in the brain. The arteries connect and form a circle at the base of the brain called the circle of Willis.
The brain also has sinuses, or veins. These carry waste and carbon dioxide away from the cranium. Some of these veins connect with the veins of the scalp and face, creating a possible way for infection to enter the cranium.
The brain also has a structure called the blood-brain barrier across which nutrients and waste are exchanged. This barrier protects the brain.
Although the brain comprises a small amount of the body’s weight, it requires a lot of energy to function. The brain uses 14 percent of the heart’s resting cardiac output to receive the oxygen and glucose it needs (Goldman, 2011).
When cerebral circulation is impaired, oxygen and glucose do not reach the brain. This can cause neurological problems. These are the most common conditions that can result from an impairment in circulation:
Stroke: When a blood clot blocks the flow of blood in the cranial artery, an infarction, or stroke can occur. The brain tissue in that area can die. When that tissue dies, whatever function that area of the brain performed—speech, movement, memory—is impaired. The amount of impairment depends on how much damage occurred and how quickly treatment is found. Some people are able to recover fully, but many have lasting disabilities. Strokes are very serious. They are the fourth leading cause of death among Americans (Stroke.org, 2013). They are also preventable.
Cerebral hemorrhage: A cerebral hemorrhage, or internal bleeding in the cranial cavity, can also happen when there is a problem with circulation. This bleeding can occur when arterial walls are weakened and burst. This forces blood into the cranial cavity. This in turn can put pressure on the cranial cavity, and cause a loss of consciousness. A cerebral hemorrhage is very serious and is usually treated as an emergency.
Hypoxia: Hypoxia occurs when an inadequate supply of oxygen is received in an area of the brain. This can be due to high altitude, pulmonary diseases, or anemia. Individuals with hypoxia often appear confused or lethargic. Brain tissue is usually not damaged, but if the cause is not relieved (such as moving to a lower altitude), coma and death can occur.
Cerebral edema: Edema is swelling, and cerebral edema is swelling due to an increase of water in the cranial cavity. This increase in water can cause pressure on the brain. This is because the brain is an enclosed area. This pressure can eventually crush or damage brain structures if it is not relieved in time.
While anyone at any age can experience problems with cerebral circulation, an individual can be at a higher risk for these conditions for the following reasons:
- high blood pressure
- being overweight
- smoking and drinking alcohol
- heart disease or atherosclerosis (hardening of the arteries)
- high cholesterol
- having a family history of heart or disease