Strokes - also called "brain attacks," happen when brain cells die because of inadequate blood flow. A stroke is considered to be a cardiovascular disease and a neurological disorder. Most strokes are caused by the blockage of an artery in the neck or brain, and the rest by bleeding into or around the brain. When brain cells die, function of the body parts they control becomes damaged or destroyed. This may include paralysis, speech problems, memory and reasoning deficits, coma, and possibly death.
A stroke occurs when a blood vessel bringing oxygen and nutrients to the brain bursts or is clogged by a blood clot or some other particle. When the brain doesn't get the needed blood flow, it is deprived of oxygen. Thus, nerve cells cannot properly function and die within minutes. And when nerve cells cannot function, the part of the body controlled by these cells cannot function either. The devastating effects of stroke are often permanent because dead brain cells are not replaced.
Multiple sclerosis (MS) - is a chronic disease of the central nervous system. It is an unpredictable condition that can be relatively benign, disabling, or devastating. Some individuals with MS may be mildly affected while others may lose their ability to write, speak, or walk -- when communication between the brain and other parts of the body becomes disrupted.
In multiple sclerosis, the body incorrectly directs antibodies and white blood cells against proteins in the myelin sheath, which surrounds nerves in your brain and spinal cord. This causes inflammation and injury to the sheath and ultimately to the nerves that it surrounds. The result may be multiple areas of scarring (sclerosis). Eventually, this damage can slow or block the nerve signals that control muscle coordination, strength, sensation and vision.
There are many possible causes of MS, including viruses, environmental factors, genetic factors, and immune system factors.