Multiple sclerosis is defined as a "degenerative inflammatory disease of the central nervous system, involving the brain, optic nerve, and spinal cord"(Brawner & Schairer, 2000). Classically, it has been described as "space and time," where dispersed areas of the central nervous system cause exacerbations and remissions over time (Brawner & Schairer, 2000). The name "multiple sclerosis" is derived from the Greek word sklerosis, meaning "hardening," where scar tissue replaces disintegrating myelin and leads to white matter in the brain and spinal cord, of sizes of a pinpoint to 1 centimeter in diameter (Boss & Farley, 2000).
Pathophysiology
The demyelination along the central nervous system leads to less controlled and coordinated movements. Autonomic nervous system abnormalities become present in heart rate and blood pressure response (Brawner & Schairer, 2000).
Etiology
Multiple sclerosis currently has three known etiologies: genetic, autoimmune, and environmental. The genetic theory is supported by a high presence of multiple sclerosis in monozygote twins (25%) and first degree relatives (Brawner & Schairer, 2000). As an autoimmune disorder, the body may "see" the myelin as a virus and produce substances to destroy it (Boss & Farley, 2000). Sentinel clinical signs, such as immunological abnormalities in blood and cerebrospinal fluid, corroborate this theory. From an environmental perspective, persons with multiple sclerosis often have geographical connections; there is a much greater prevalence of multiple sclerosis in the Northern and Southern hemispheres (80/100,000) than at the equator (1/100,000).
Epidemiology
The age of onset of multiple sclerosis is between 20-40 years, and it affects more women than men (1.7 to 1 ratio). As mentioned previously, there is a great variability in prevalence (1.5/100,000 to 11/100,000)(Brawner & Schairer, 2000). In the US, multiple sclerosis has been diagnosed in over 350,000 persons (MS Foundation Link).
Diagnosis
A diagnosis is determined from the presence of exacerbations and remissions of neurological symptoms, and two or more central nervous system white matter lesions, where other medical explanations, like stroke or lupus, cannot explain findings (Brawner & Schairer, 2000)(Rosenthal & Scheinberg, 2000). Laboratory tests such as the MRI, can support the diagnosis (Brawner & Schairer, 2000), and evaluative/rating scales, like Dr. John Kurtzke's Expanded Disability Status Scale (EDSS), and the Incapacity Status Scale (ISS), help to gauge the degree of disability (Rosenthal & Scheinberg, 1990).
Clinical Presentations, Course, and Symptoms
Multiple sclerosis is classified clinically into four categories: benign (20%) with nearly complete remission and little disability, relapsing remitting (25%), chronic relapsing (40%), and chronic progressive (15%) which is very debilitating from the beginning and has a rapid decline. Though there is no "typical" clinical course for multiple sclerosis, most (70%) recover after the first exacerbation/onset; post 10 years, 50% can work and do housework; post 15 years, 50% need walking assistance devices; and post 25 years, 50% cannot walk despite assistive devices (Brawner & Schairer, 2000). Symptoms include ataxia, weakness, fatigue, sensitivity to temperature increases, sensory disturbances, spasms, voluntary bladder control, and visual problems (Brawner & Schairer, 2000)(Petajan & White, 1999).