Such things as heart block, ventricular fibrillation, or infarction can be the cause of the decreased output. A third category involves the diseases of the arterial walls. The most common finding in narrowed arteries of the brain is atheroma. This hardening of the arteries, as it is frequently called, can affect the arteries leading to the brain or those within the skull and brain itself. A number of other conditions can further complicate this condition, such as, myocardial infarction or anemia.
Atherosclerosis is common in patients who are of middle or old age.
It may complicate other conditions such as, diabetes and hypertension. The actual effect of the atheroma depends on the location and extent of the lesion. If a large portion of the brain undergoes ischemia, then the neuroglia in that region will proliferate and invade the area. If the lesion is in a small area supplying a limited amount of nervous tissue the damage and sequelae may be small. However, if there is generalized ischemia due to narrowing of the cerebral arteries the brain will undergo a diffuse atrophy.