About This Condition
Multiple sclerosis (MS) is a slowly progressive, degenerative condition in which the myelin sheaths surrounding nerves in the brain and spinal cord are lost. Myelin sheaths are a type of connective tissue, composed of fats and proteins, that insulate nerve fibers. They protect nerves and are required for effective transmission of nerve impulses.
Indirect evidence suggests that MS may be an autoimmune disease, wherein the immune system attacks myelin in the central nervous system. MS is more common among people who live in temperate climates compared with those who live in tropical climates and receive greater exposure to the sun. Possible causes for MS may include genetic susceptibility, diet, environmental toxins, viral infections, and exposure to dogs, cats, or caged birds.1 Epstein-Barr virus has also been named as a risk factor,2 though the real cause or causes of MS are unknown.
MS is characterized by various neurological symptoms, with remissions and recurrent exacerbations. The most common symptoms are paresthesia (numbness and tingling) in the extremities, trunk, or on one side of the face. Muscle weakness, loss of coordination of a leg or hand, and visual disturbances (such as partial blindness in one eye, dim vision, or double vision) are common in MS. Limbs that fatigue easily, difficulty in walking, difficulty with bladder control, vertigo, and mood disturbances may appear years before MS is diagnosed. The course of the disease is highly varied and unpredictable. In most people, the disease remits for varying periods of time. However, symptoms usually recur, and the progression is often relentless.