Parkinson Disease
Parkinson Disease, disorder of the nervous system that affects muscle control. Marked by trembling of the arms and legs, muscular rigidity, and poor balance, Parkinson disease is slowly progressive, worsening over time. Eventually symptoms may cause problems with walking or talking and, in some people, difficulty thinking. Physicians do not know how to cure Parkinson disease, but drug therapy or surgery may alleviate some of the most troubling symptoms. The disease is named for British physician James Parkinson, who first described it in 1817. In a report describing six patients, Parkinson called the disorder paralysis agitans, Latin words that mean “shaking palsy.”
Parkinson disease develops as a part of the brain known as the substantia nigra degenerates. The substantia nigra is located in the midbrain, halfway between the cerebral cortex and the spinal cord. In healthy people, the substantia nigra contains certain nerve cells, called nigral cells, that produce the chemical dopamine. Dopamine travels along nerve cell pathways from the substantia nigra to another region of the brain, called the striatum. In the striatum, dopamine activates nerve cells that coordinate normal muscle activity. In people with Parkinson disease, nigral cells deteriorate and die at an accelerated rate, and the loss of these cells reduces the supply of dopamine to the striatum. Without adequate dopamine, nerve cells of the striatum activate improperly, impairing a person’s ability to control movement.
Parkinson disease most notably affects motor control (muscle activity). The disease progresses differently for each individual—symptoms develop swiftly in some people and slowly in others. Some Parkinson patients may develop problems that affect their intellect or ability to reason, or they may suffer from depression or anxiety.
Doctors look for the presence of four principal symptoms in patients they suspect may have Parkinson disease. Tremor (the involuntary shaking of limbs) is the major symptom for most people who have Parkinson disease, although at least a third of people diagnosed with the disease do not develop this symptom. Tremor typically begins in one hand but may eventually progress to the other hand, as well as to the arms, legs, and jaw.
There is no known cure for Parkinson disease—that is, no treatment that prevents the disease from progressing. But the symptoms of the disease can be controlled by various drugs such as Levodopa, and, in some cases, by surgery.
Parkinson disease develops as a part of the brain known as the substantia nigra degenerates. The substantia nigra is located in the midbrain, halfway between the cerebral cortex and the spinal cord. In healthy people, the substantia nigra contains certain nerve cells, called nigral cells, that produce the chemical dopamine. Dopamine travels along nerve cell pathways from the substantia nigra to another region of the brain, called the striatum. In the striatum, dopamine activates nerve cells that coordinate normal muscle activity. In people with Parkinson disease, nigral cells deteriorate and die at an accelerated rate, and the loss of these cells reduces the supply of dopamine to the striatum. Without adequate dopamine, nerve cells of the striatum activate improperly, impairing a person’s ability to control movement.
Parkinson disease most notably affects motor control (muscle activity). The disease progresses differently for each individual—symptoms develop swiftly in some people and slowly in others. Some Parkinson patients may develop problems that affect their intellect or ability to reason, or they may suffer from depression or anxiety.
Doctors look for the presence of four principal symptoms in patients they suspect may have Parkinson disease. Tremor (the involuntary shaking of limbs) is the major symptom for most people who have Parkinson disease, although at least a third of people diagnosed with the disease do not develop this symptom. Tremor typically begins in one hand but may eventually progress to the other hand, as well as to the arms, legs, and jaw.
There is no known cure for Parkinson disease—that is, no treatment that prevents the disease from progressing. But the symptoms of the disease can be controlled by various drugs such as Levodopa, and, in some cases, by surgery.
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