Parkinson's disease
Parkinson's disease: Excerpt from Handbook of Diseases
Parkinson’s disease (also known as shaking palsy and paralysis agitans) characteristically produces progressive muscle rigidity, akinesia, and involuntary tremor. Deterioration is a progressive process. Death may result from complications, such as aspiration pneumonia or another infection.
Parkinson’s disease, one of the most common crippling diseases in the United States, strikes 2 in every 1,000 people older than age 50. It also occurs in younger adults and, rarely, in children. It’s one of the most common neurologic disorders of the elderly population.
Causes
Although the cause of Parkinson’s disease is unknown, study of the extrapyramidal 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
The cardinal signs and symptoms of Parkinson’s disease are muscle rigidity, bradykinesia or akinesia, loss of position sense with postural instability, and an insidious tremor that begins in the fingers (unilateral pill-roll tremor), increases during stress or anxiety, and decreases with purposeful movement and sleep.
Muscle rigidity results in resistance to passive muscle stretching, which may be uniform (lead-pipe rigidity) or jerky (cogwheel rigidity). Akinesia causes the patient to walk with difficulty (gait lacks normal parallel motion and may be retropulsive or propulsive).
Parkinson’s disease also produces a high-pitched, monotone voice; drooling; a masklike facial expression; loss of posture control (the patient walks with body bent forward); and dysarthria, dysphagia, or both. Occasionally, akinesia may also cause oculogyric crises (eyes are fixed upward, with involuntary tonic movements) or blepharospasm (eyelids are completely closed).
Parkinson’s disease results in dementia in about 10% of those diagnosed. Theorists believe this may be due to the advanged age of some patients or a coexisting disorder such as arteriosclerosis that results in cognitive deficits.
Diagnosis
Generally, laboratory data are of little value in identifying Parkinson’s disease; diagnosis is based on the patient’s age and history and on the characteristic clinical picture. However, urinalysis may support the diagnosis by revealing decreased dopamine levels.
A conclusive diagnosis is possible only after ruling out other causes of tremor, involutional depression, cerebral arteriosclerosis and, in patients younger than age 30, intracranial tumors, Wilson’s disease, or phenothiazine or other drug toxicity.
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 those unresponsive to drugs, stereotactic neurosurgery.
Drug therapy
Drug therapy usually includes levodopa, a dopamine replacement that’s most effective during the early stages. It’s given in increasing doses until symptoms are relieved or the patient has an adverse reaction to it. Because adverse reactions can be serious, levodopa is commonly given 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 antivirals such as amantadine. Selegiline, an enzyme-inhibitor, helps conserve dopamine and enhances the therapeutic effect of levodopa.
Treatment may include dopamine agonists, such as bromocriptine and ropinirole, which act directly on dopamine receptors. Catechol-O-methyltransferase inhibitors, such as entacapone and tolcapone, are given with dopamine; this new class of drugs blocks an enzyme that breaks down peripheral levodopa.
UNDER STUDY: Research on the oxidative stress theory has caused a controversy in drug therapy for Parkinson’s disease. Although levodopa (with carbidopa) has traditionally been a first-line drug in management of the disease, the drug has also been associated with an acceleration of the disease process. Selegiline followed by levodopa (with carbidopa) may provide increased protection.
Stereotactic neurosurgery
When drug therapy fails, stereotactic neurosurgery may be an alternative. With this procedure, electrical coagulation, freezing, radioactivity, or ultrasound destroys the ventrolateral nucleus of the thalamus to prevent involuntary movement. It’s most effective in young, otherwise-healthy persons with unilateral tremor or muscle rigidity; however, neurosurgery can help by relieving symptoms.
Deep brain stimulation is another procedure that may be performed to relieve symptoms. This procedure involves implanting an electrode in the affected area of the brain. The electrode is powered by a battery pack similar to those used with cardiac pacemakers.
Physical therapy
Individually planned physical therapy complements drug treatment and neurosurgery to maintain normal muscle tone and function. Appropriate physical therapy includes active and passive range-of-motion exercises, routine daily activities, walking, and baths and massage to help relax muscles.
Special considerations
❑ Effectively caring for the patient with Parkinson’s disease requires careful monitoring of drug treatment, emphasis on teaching self-reliance, and generous psychological support.
❑ Monitor drug treatment so that the dosage can be adjusted to minimize adverse reactions, including dry mouth, nausea, insomnia, confusion, and hallucinations.
❑ If the patient has surgery, watch for signs of hemorrhage, infection, and increased intracranial pressure by frequently checking his level of consciousness and vital signs.
❑ Encourage independence. The patient with excessive tremor may achieve partial control of his body by sitting on a chair and using its arms to steady himself. Remember that fatigue may cause him to depend more on others.
❑ Scheduling meals around the time of maximum drug efficiency will help minimize complications and promote good nutrition.
❑ Help the patient overcome problems related to eating and elimination. For example, if he has difficulty eating, offer supplementary or small, frequent meals to increase caloric intake.
❑ Help establish a regular bowel routine by encouraging the patient to drink at least 2,000 ml of liquids daily and to eat high-bulk foods. He may need an elevated toilet seat to assist him from a standing to a sitting position.
❑ Give the patient and his family emotional support. Teach them about the disease, its progressive stages, and adverse drug effects.
❑ Show the family how to prevent pressure ulcers and contractures with proper positioning. Explain that the patient should avoid high-protein meals (this impairs the action of levodopa), and explain household safety measures to prevent accidents.
❑ Instruct the patient and his family on proper food consistency, correct positioning, and swallowing strategies to decrease dysphagia and avoid aspiration. Also, teach the family how to assess the patient for aspiration.
❑ Help the patient and his family express their feelings and frustrations about the progressively debilitating effects of the disease.
❑ Establish long- and short-term treatment goals, and be aware of the patient’s need for intellectual stimulation and diversion.
❑ To obtain more information, refer the patient and his family to the National Parkinson Foundation or the United Parkinson Foundation.
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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» Next page: Tremors (Signs & Symptoms: A 2-in-1 Reference for Nurses)
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