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Columbia University Press
Parkinson's disease
or Parkinsonism, degenerative brain disorder first described by the English surgeon James Parkinson in 1817. When there is no known cause, the disease usually appears after age 40 and is referred to as Parkinson's disease. Parkinsonism usually refers to similar symptoms resulting from head injury, encephalitis, syphilis, carbon monoxide poisoning, cerebral arteriosclerosis, or use of MPTP (a synthetic narcotic). The disorder is also termed paralysis agitans, or shaking palsy.

Parkinson's disease is a debilitating and progressive disorder in which the chemicals that facilitate electrical transmission between nerve cells are depleted. It was the first disease to be treated by drugs that replace deficient neurotransmitters. Symptoms usually begin in middle to later life with trembling of the lips and hands, loss of facial expression, and muscular rigidity. As it progresses it may bring on body tremors, particularly in muscles at rest. Movements become slow and difficult; walking degrades to a shuffle. After many years physical incapacity may occur. Dementia occurs in at least 50% of the patients; depression is also common.

When drugs such as levodopa (L-Dopa) are taken orally, many of the worst symptoms are lessened. New drugs such as pramipexole (Mirapex) and ropinirole (Requip) can delay the need for levodopa. Apomorphine (Apokyn) is used treat episodes of reduced mobility in patients with advanced Parkinson's that responds less effectively to levodopa. Future approaches to treatment include a focus on early detection and slowing progression of the disease. Encouraging results have been reported from surgical insertion of a pacemakerlike device deep in the brain to suppress uncontrolled movements, but surgical transplantation of fetal dopamine-producing cells failed to show significant benefits in a controlled study. Traditional surgery can alleviate some tremors, and physical therapy may help mobility.