An estimated one million people in the United States have Parkinson's disease. It's a motor system disorder that is both chronic and progressive — that is, it persists and gets worse over a long period of time. The disease is characterized by tremors, stiffness in the limbs, slowness of movement (bradykinesia) and impaired balance. Parkinson's is not contagious, nor is it usually inherited.
There are a number of disorders with similar symptoms called parkinsonism, including postencephalitic parkinsonism and arteriosclerotic parkinsonism. However, Parkinson's disease is by far the most common form of parkinsonism.
What are the symptoms of Parkinson's disease?
Who gets Parkinson's disease, and what causes it?
How is Parkinson's disease diagnosed?
What is the treatment for Parkinson's disease?
What are the Symptoms of Parkinson's Disease?
Parkinson's disease is characterized by four main symptoms.
- Rigidity — stiffness when the arm, leg or neck is moved back and forth. All muscles have an opposing muscle &mdash so for movement to take place, one muscle must contract while its opposing muscle relaxes. Rigidity occurs when the balance between muscles and opposing muscles is disturbed, leaving the patient feeling stiff or weak.
- Resting tremor — tremors, or shaking, that become more prominent when the patient is sitting quietly at rest. Typically, tremor begins in the hand, but sometimes the jaw or a foot is affected first. During the early stages of the disease, tremors affect only one side of the body in most patients — later, the tremor may become more generalized. Tremor is rarely the cause of disability — it improves during intentional movement and disappears during sleep.
- Bradykinesia — slowness in initiating movement. This symptom can come and go — one moment, the patient can move easily, and then suddenly needs help. Activities such as washing or dressing may take several hours. Bradykinesia can cause the faces of Parkinson's patients to become less animated, taking on a mask-like, non-expressive quality.
- Loss of postural reflexes — poor balance or a tendency to fall. This symptom causes patients to develop a forward or backward lean. When bumped or when starting to walk, patients have a tendency to step backwards before continuing forward. Postural instability can also cause patients to walk with a stooped posture.
Secondary Parkinson's symptoms that may occur include the following.
Some of these symptoms may be made worse or even caused by medication for Parkinson's. Late in the course of the disease, a few patients suffer from dementia.
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Who Develops Parkinson's disease, and What Causes It?
Parkinson's disease usually strikes in late middle age, affecting people over the age of 50. The average age of onset is 60 years — only five to 10 percent of people suffering from Parkinson's are under the age of 40. The disease affects men and women equally.
All forms of parkinsonism occur when certain nerve cells in an area of the brain called the substantia nigra die or stop working properly.
These nerve cells normally produce a chemical called dopamine which helps the substantia nigra communicate with another area of the brain, the corpus striatum. This communication is necessary for smooth, purposeful body movement — without enough dopamine, the nerve cells of the stratum fire out of control, resulting in the symptoms of parkinsonism. Studies have shown that Parkinson's disease patients can lose up to 80 percent of their dopamine-producing brain cells.
In most forms of parkinsonism, there is a known or suspected cause for the death of dopamine-producing cells in the substantia nigra — sometimes, another neurological condition is the cause. However, doctors don't know the cause of Parkinson's disease. Research in this area is ongoing.
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How is Parkinson's Disease Diagnosed?
There is no definitive diagnostic test for Parkinson's disease. Making an accurate diagnosis in the early stages of Parkinson's can be difficult, even for an experienced neurologist. Tremor is often the first symptom to appear — that's usually why the patient first sees a doctor.
However, tremor can have many causes, and people with Parkinson's almost always exhibit other classic symptoms also. For that reason, patients with tremors may be observed over a period of time. Parkinson's can be diagnosed when it's clear that tremors are consistently present and other symptoms appear. Other forms of parkinsonism have similar symptoms but require different treatment, so it's important to get a precise diagnosis as soon as possible.
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What is the Treatment for Parkinson's Disease?
Unfortunately, there is no cure for Parkinson's disease. Although Parkinson's disease is a progressive disorder, how fast it progresses varies widely in different patients. Many patients enjoy years of progressive living after developing the disease. In fact, drug therapy can provide dramatic relief from many of the symptoms.
Current drug therapy focuses mostly on dopamine replacement. The most powerful drug used to alleviate Parkinson's symptoms is called levadopa (or L-dopa). Nerve cells use levadopa to make dopamine, which can then be used by the brain. Bradykinesia and rigidity are the symptoms that respond best to levadopa treatment, while problems with tremors and balance may be only marginally reduced.
There are some side effects to levadopa treatment — the most common are nausea, vomiting, low blood pressure, involuntary movements and restlessness. Sometimes, depression can be caused or made worse by levadopa therapy. Doctors can usually alleviate some side effects through adjustments to the patient's dosage or by prescribing a drug called carbidopa to be taken along with levadopa. After two to five years of treatment with levadopa, the drug's effectiveness can begin to fluctuate for some patients. To help alleviate this, doctors may prescribe smaller doses of the drug to be taken at shorter intervals.
A variety of other drugs are used to treat Parkinson's disease symptoms and can be used alone or in combination. Often, doctors will try these in the early stages of the disease, before prescribing the more powerful levadopa. Because every patient is different, it sometimes takes time to determine which dosage of what drugs is most effective. As the disease progresses, doctors may need to make adjustments in the patient's medication.
Tremors can sometimes be relieved for several months through injections of a tiny amount of botulism toxin, which blocks spasms by slightly weakening the affected muscles.
There are some surgical techniques that can be used to help the symptoms of Parkinson's, especially severe tremor. For example, crypothalamotomy is the insertion of a supercooled metal tip into the brain to destroy the brain area that produces tremors. Other surgical techniques, including fetal brain tissue implantation, are still in the experimental stage.
It's especially important that Parkinson's patients maintain good general health and continue to exercise in order to avoid depression. Fatigue, anxiety and unhappiness can aggravate Parkinson's symptoms. Getting involved in support groups and physical and occupational therapy programs can be a great help in dealing with the disease.
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