Parkinson's Disease

Named for James Parkinson, the English doctor who wrote the first accurate description of the disease in 1817, Parkinson's disease (also known as shaking palsy) characteristically produces progressive muscle rigidity, akinesia, and involuntary tremor. Deterioration is a progressive process. Death may result from complications, such as aspiration pneumonia or some other infection.

Parkinson's disease, one of the most common crippling diseases in the United States, affects men more often than women. According to current statistics, it strikes 1 in every 100 people over age 60. Because of increased longevity, this amounts to roughly 60,000 new cases diagnosed annually in the United States alone. Secondary to the aging of the population, an increase in cases is predicted.

Causes

Although the cause of Parkinson's disease is unknown, study of the extra pyramidal brain nuclei (corpus striatum, globus pallidus, substantia nigra) has established that a dopamine deficiency prevents affected brain cells from performing their normal inhibitory function within the central nervous system.

CLINICAL TIP

More research on the pathogenesis of Parkinson's disease focuses on damage to the substantia nigra from oxidative stress. Oxidative stress is believed to cause alterations in brain iron content, impair mitochondrial function, alter antioxidant and protective systems, reduce glutathione, and damage lipids, proteins, and deoxyribonucleic acid.

Signs and symptoms

People with Parkinson's disease experience tremors (shakiness) as a result of the damage to their nerve cells. The tremor of Parkinson's disease gets worse when the person is at rest and better when the person moves. The tremor may affect one side of the body more than the other, and can affect the lower jaw, arms and legs. Handwriting may also look "shaky" and smaller than usual. Other symptoms of Parkinson's disease include nightmares, depression, excess saliva, difficulty turning over in bed and buttoning clothes or cutting food, and problems with walking.

Diagnosis

If you suspect you have early symptoms of Parkinson's disease, your doctor will take a complete medical history and perform a thorough physical exam. He or she will check for the physical signs Parkinson's, including tremor, rigid muscles, and slow movements. While there is no specific diagnostic test for Parkinson's disease, there are some tests your doctor may perform to rule out other diseases that can cause similar symptoms. These might include brain scans, blood tests, a lumbar puncture to check spinal fluid for signs of bacterial infections, and x-rays.

Treatment

Because there's no cure for Parkinson's disease, the primary aim of treatment is to relieve symptoms and keep the patient functional as long as possible. Treatment consists of drugs, physical therapy and, in severe disease states unresponsive to drugs, stereotactic neurosurgery.

Drug therapy

Drug therapy usually includes levodopa, a dopamine replacement that is most effective during early stages. It's given in increasing doses until symptoms are relieved or adverse effects appear. Because adverse effects can be serious, levodopa is frequently given in combination with carbidopa to halt peripheral dopamine synthesis.

When levodopa proves ineffective or too toxic, alternative drug therapy includes anticholinergics such as trihexyphenidyl; antihistamines such as diphenhydramine; and amantadine, an antiviral agent. Selegiline, an enzymeinhibiting agent, allows conservation of dopamine and enhances the therapeutic effect of levodopa.

CLINICAL TIP

Research on the oxidative stress theory has caused a controversy in drug therapy for Parkinson's disease. Whereas levodopa/ carbidopa has traditionally been a first­line drug in management, it has been associated with an acceleration of the disease process. Selegiline followed by levodopa/carbidopa may provide increased protection.

Stereotactic neurosurgery

When drug therapy fails, stereotactic neurosurgery may be an alternative. In this procedure, electrical coagulation, freezing, radioactivity, or ultrasound destroys the ventrolateral nucleus of the thalamus to prevent involuntary movement. This is most effective in young, otherwise healthy persons with unilateral tremor or muscle rigidity. Neurosurgery can only relieve symptoms.

Physical therapy

Individually planned physical therapy complements drug treatment and neurosurgery to maintain normal muscle tone and function. Appropriate physical therapy includes both active and passive range-of-motion exercises, routine daily activities, walking, and baths and massage to help relax muscles.

Prevention

Right now, researchers don't know how Parkinson's can be prevented, if at all.