Ischemia within the arteries branching from the internal carotid artery may result in symptoms such as blindness in one eye, weakness in one arm or leg, or weakness in one entire side of the body. Ischemia within the arteries branching from the vertebral arteries in the back of the brain may result in symptoms such as dizziness, vertigo, double vision, or weakness on both sides of the body. Other symptoms include difficulty speaking, slurred speech, and the loss of coordination. The symptoms of brain ischemia range from mild to severe. Further, symptoms can last from a few seconds to a few minutes or extended periods of time. If the brain becomes damaged irreversibly and infarction occurs, the symptoms may be permanent.Similar to cerebral hypoxia, severe or prolonged brain ischemia will result in unconsciousness, brain damage or death,  mediated by the ischemic cascade.Multiple cerebral ischemic events may lead to subcortical ischemic depression, also known as vascular depression. This condition is most commonly seen in elderly depressed patients. Late onset depression is increasingly seen as a distinct sub-type of depression, and can be detected with an MRI. Causes
Brain ischemia has been linked to a variety of diseases or abnormalities. Individuals with sickle cell anemia, compressed blood vessels, ventricular tachycardia, plaque buildup in the arteries, blood clots, extremely low blood pressure as a result of heart attack, and congenital heart defects have a higher predisposition to brain ischemia in comparison to the average population. Sickle cell anemia may cause brain ischemia associated with the irregularly shaped blood cells.
Sickle shaped blood cells clot more easily than normal blood cells, impeding blood flow to the brain.Compression of blood vessels may also lead to brain ischemia, by blocking the arteries that carry oxygen to the brain. Tumors are one cause of blood vessel compression.Ventricular tachycardia represents a series of irregular heartbeats that may cause the heart to completely shut down resulting in cessation of oxygen flow. Further, irregular heartbeats may result in formation of blood clots, thus leading to oxygen deprivation to all organs.Blockage of arteries due to plaque buildup may also result in ischemia. Even a small amount of plaque build up can result in the narrowing of passageways, causing that area to become more prone to blood clots. Large blood clots can also cause ischemia by blocking blood flow.A heart attack can also cause brain ischemia due to the correlation that exists between heart attack and low blood pressure. Extremely low blood pressure usually represents the inadequate oxygenation of tissues. Untreated heart attacks may slow blood flow enough that blood may start to clot and prevent the flow of blood to the brain or other major organs. Extremely low blood pressure can also result from drug overdose and reactions to drugs. Therefore, brain ischemia can result from events other than heart attacks.Congenital heart defects may also cause brain ischemia due to the lack of appropriate artery formation and connection.