Multiple Sclerosis: a disorder of the central nervous system marked by weakness, numbness, a loss of muscle coordination, and problems with vision, speech, and bladder control. Multiple sclerosis is thought to be an autoimmune disease in which the body's immune system destroys myelin. (NCIt) A condition characterized by areas of damage (lesions) on the brain and spinal cord. These “lesions” are associated with destruction of the covering that protects nerves and promotes the efficient transmission of nerve impulses (the myelin sheath) and damage to nerve cells. (GHR) Causes paralysis, blindness, and other sensory-motor and cognitive disabilities. Caused by defective electrical communication between neurons that results when the body’s immune system attacks the “myelin” sheath, stripping the electrical insulation from an axon. (Fields, 37) Because nerves in any part of the brain or spinal cord may be damaged, patients with multiple sclerosis can have symptoms in many parts of the body. (PubMedHealth2) An estimated 1.1 to 2.5 million people worldwide have multiple sclerosis. Although the reason is unclear, this condition is more common in regions that are farther away from the equator. In Canada, parts of the northern United States, western and northern Europe, Russia, and southeastern Australia, the condition affects approximately 1 in 2,000 to 2,400 people. It is less common closer to the equator, such as in Asia, sub-Saharan Africa, and parts of South America, where about 1 in 20,000 people are affected. For unknown reasons, most forms of multiple sclerosis affect women twice as often as men. (GHR)
Parkinson’s Disease: a chronic, slowly progressive disorder of the central nervous system that occurs chiefly in later life as a result of “degenerative” changes in the brain. Produces “tremor,” rigidity of the limbs, and slowness and imprecise movements. (Oxford) A degenerative disorder in which neurons rich in the “neurotransmitter” “dopamine” die over time. (Nicolelis, 179) Causes rigidity, tremor and poverty of movements involving the entire body including the face. Early in this disease, the rigidity and tremor affect only one hand. (Ramachandran, 269) Attacks a certain class of “interneurons.” (Kandel 67) Arvid Carlsson argued that Parkinson’s Disease may result from a lowered concentration of dopamine in regions of the brain that are involved in motor control. He and others tested this idea and found that they could reverse the symptoms by giving patients additional dopamine. (Kandel, 356) No known cure for Parkinson’s disease exists. Thus, treatment is symptomatic and directed toward support and comfort. (Kolb, 595)