Parkinson disease

: An abnormal condition of the nervous system caused by degeneration of an area of the brain called the basal ganglia, and by low production of the neurotransmitter dopamine. The first gene connected to Parkinson’s was recently identified, but it is probably caused by a combination of genes and other factors. The disease results in rigidity of the muscles, slow body movement and tremor. Most patients are over 50, but at least 10 percent are under 40. Treatment is by medication, such as levodopa (brand name: Larodopa) and carbidopa (brand name: Sinemet); a surgically implanted device that helps control the shaking has recently become available. In some cases, surgery on the globus pallidus or thalamus has proved helpful. A number of new and innovative therapies are currently under development. Also known as paralysis agitans and shaking palsy.

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a slowly progressive disorder affecting the basal ganglia, usually occurring in late life, with an average age of onset of 60 years; however, a young-onset form diagnosed at or before 40 years of age is distinguished. It is characterized clinically by masklike facies, resting tremor, slowing of voluntary movements, festinating gait, flexed posture, and muscle weakness, sometimes with excessive sweating and feelings of heat. Pathologically, there is degeneration of dopaminergic neurones of the pars compacta of the substantia nigra, resulting in dramatic decrease in the levels of dopamine in the substantia nigra and corpus striatum.