Another "node your homework"....

History:

In 1817, James Parkinson, a British physician, wrote a monograph, “An Essay on the Shaking Palsy”. In it, he described a disease he termed “shaking palsy” (paralysis agitans). He noted “involuntary tremulous motion, with lessened muscular power, in parts not in action and even when supported; with a propensity to bend the trunk forwards, and to pass from a walking to a running pace: the senses and the intellect being uninjured.” This disease, now known as Parkinson’s disease, is the subject of this writeup.

Etiology:

Parkinson’s disease is a progressively degenerative neurological disease. Its symptoms result from the degenerative loss of dopamine-producing neurons in two nuclei within the brain; one within the globus pallidum, and the other within the thalamus.

There are several different etiologies for Parkinson’s disease, including medications such as neuroleptics, antiemetics and some antihypertensives, toxins such as carbon monoxide, cyanide, manganese, herbicides, carbon disulfide, methanol and lacquer thinner, and the recreational drug Ecstasy. Other etiologies include acute brain infarction, structural brain lesions, and brain trauma (a subset of parkinsonism, dementia pugilistica, is seen in boxers). Some of Parkinson’s more famous victims in recent history include Muhammad Ali, Michael J. Fox, and Janet Reno.

Epidemiology:

Parkinson’s disease occurs worldwide. It affects approximately one million people in the United States. 50,000 new cases are diagnosed each year. There is an upward trend, due to the aging of the population as well as increased sensitivity of detection. The typical age of onset is between 55 and 60 years. However, five percent of all cases occur in persons under the age of 40. The male to female ratio is three to two.

A history of anxiety or depression doubles the risk of developing Parkinson’s disease. It is unknown whether anxiety and depression are early nonmotor manifestations of the disease, whether they in themselves increase the risk, or whether they simply tend to occur together. On the other hand, caffeine and nicotine intake has been shown to decrease the risk of developing Parkinson’s disease. It has been hypothesized that this may be due to a physical or psychological intolerance to caffeine or nicotine among people with a propensity for developing Parkinson’s disease, or that caffeine may increase central dopaminergic tone.

There is some evidence indicating a possible hereditary factor. Parkinson’s disease can be traced through several large family groups in Italy and Iceland; however, the Department of Veterans’ Affairs Twin Study failed to show this link in disease that occurred at the typical age. There was a genetic factor in disease which occurred before age 40.

Symptoms:

Symptoms of Parkinson’s disease usually begin very gradually, and may initially be taken for normal changes of aging. The initial symptom is usually an unilateral hand tremor which is most pronounced at rest. It intensifies with movement of the unaffected hand; however, it decreases and may disappear with use of the affected hand. Its intensity fluctuates, and increases with stress. The patient may also have a tremor in the lower jaw, tongue, and legs. Handwriting changes, such as decreased size and legibility of writing, slowing of movements, difficulty rising from a sitting position, and gait changes such as shuffling or foot dragging also occur. These symptoms initially manifest asymmetrically, and progress to the opposite side within two to three years of their appearance. Reduced volume and clarity of speech, as well as an absence of facial expression, are also evident. Rigidity of the limbs affected by the tremor leads to the characteristic “cogwheeling” movements, and can be assessed by performing range-of-motion testing. An increased muscle tone and lack of relaxation will be noted. Postural instability is a late sign of Parkinson’s disease.

In addition to the motor symptoms discussed above, there is a wide range of nonmotor symptoms as well.

Cognitive decline manifests as visual disturbance, memory deficit, or frank dementia. Depression is almost universal among Parkinson’s patients. Sleep disturbances such as frequent nighttime waking, excessive daytime drowsiness, and “restless leg” syndrome are common. Additionally, REM sleep behavior disorder, a condition in which physical activity occurs during REM sleep, may cause injur to either the patient or their bed partner.

Constipation, urinary problems, orthostatic hypotension and disturbances of diaphoresis, as well as limb paresthesias, sexual dysfunction and an impaired sense of smell are associated symptoms as well. Late in the course of the disease, dysphagia and dyspnea occur.

Differential diagnosis:

There are several other disorders which can be confused with Parkinson’s disease:

  • Essential tremor is a tremor which is usually absent at rest. It worsens with voluntary movement, and is significantly stronger than the tremor of Parkinson’s disease. It usually involves the head, but not the legs. Facial expression and movements remain normal. Symptoms are symmetrical bilaterally. Rigidity, gait changes and postural instability do not occur. Essential tremor does not respond to levodopa.
  • Alzheimer’s disease may produce symptoms including gait changes, rigidity and slowed movements, but resting tremor will be absent.
  • Huntington’s chorea is a hereditary disorder characterized by dementia, rigidity, and slowed movements. The main differentiating symptom is chorea, as opposed to the tremor characteristic of Parkinson’s disease. Approximately one third of Huntington’s patients respond to levodopa.

Medical management:

The mainstay of current Parkinson’s disease management is medication therapy. The first medication used for the treatment of Parkinson’s disease beginning in 1884 was apomorphine. In 1969, with a greater understanding of the disease process, levodopa was introduced. Although good symptom control was achieved, levodopa had a host of severe side effects. Addition of carbidopa provided better symptom control with fewer side effects. In recent years, the addition of a catechol-O-transferase (COMT) inhibitor has allowed reduced dosages of levodopa/carbidopa to be used, providing greater dopaminergic effect as well as longer duration of effectiveness.

Dopamine agonists, which mimic the action of dopamine, have also been introduced, and may be used in early Parkinson’s disease as monotherapy or, later, in combination with levodopa/carbidopa. Amantadine, which has only a limited effect on the symptoms of Parkinson’s disease, has been used to reduce the choreic movements that can be a side effect of dopaminergic therapy. Anticholinergics are no longer used for most patients, since they have a worse side effect profile and no greater effect than levodopa or the dopamine agonists. Selegiline, released in the US in 1989, has caused some controversy because, although it has little effect on Parkinson’s disease symptoms, there are hints that it might slow the progression of the disease.

For more information, see Antiparkinson agents.

Surgical management:

Surgical treatment of Parkinson’s disease was first introduced in the 1950s, when thalamotomy was discovered to relieve tremor and rigidity, although it did not affect the slowed movements. Pallidotomy was found to improve tremor, rigidity and bradykinesia. In 1961, the introduction of levodopa greatly decreased the number of ablative procedures performed. Over time, it has become clear that long-term levodopa therapy becomes a balancing act between the symptoms of Parkinson’s disease and the side effects of the medication. For advanced Parkinson’s disease, surgery has once again become an option.

There are three sites within the brain that are targeted in the neurosurgical treatment of Parkinson’s disease: the globus pallidus interna, the subthalamic nucleus, and the ventralis intermedius nucleus of the thalamus. The current theory in surgical treatment is that the globus pallidus interna and the subthalamic nucleus are overactive. The two methods for decreasing this abnormal activity are ablation and deep brain stimulation.

Ablation is performed by introducing an electrode into the targeted area and heating it in order to produce a small necrotic area. This process is immediately effective, but irreversible. Deep brain stimulation involves the introduction of an implanted electrode into the target area. High-frequency stimulation of the area then temporarily creates the same effect as ablation, but is reversible. The electrode is controlled by a pulse generator implanted under the clavicle. The amplitude of the stimulation is adjustable, so it can be titrated to the response.

Generally, medication dosages can be reduced significantly after these procedures, but not eliminated.

Experimental treatments:

A newer, controversial treatment is stem cell transplantation. The approaches that have been attempted include adrenal medullary grafts, pig xenografts, and embryonic dopamine neuron transplants. None of these have had a success rate approaching the standard surgical treatments. Younger Parkinson’s disease patients had slight improvement in their motor scores, but there was a small but significant population that developed intractable dyskinesias. All of these methods remain at the experimental stage. There is also ongoing research into methods of stimulating the stem cells that are present in every adult’s brain to migrate to a damaged area, multiply and replace the damaged neurons.

Gene therapy is another experimental treatment aimed at stopping the loss of dopaminergic cells. This treatment would involve virally modifying the cells by replacing a defective gene or inserting a neuroprotective or neurorestorative protein.

Research:

A research model for Parkinson’s disease was discovered by accident in the 1980s when some people in California, while attempting to synthesize Demerol, accidentally synthesized MPTP. This compound induces Parkinson’s disease symptoms, and its discovery has allowed researchers to create animal models of Parkinson’s disease and advance their understanding of it.

Nonpharmacological treatment:

An important aspect of the treatment of Parkinson’s disease is the use of nonpharmacological treatments. These include physical therapy, nutritional support, and patient and caregiver education. Acupuncture may provide some temporary relief from rigidity.

Eating foods high in antioxidants, such as blueberries, strawberries, prunes, kale and spinach, and taking antioxidant vitamin supplements such as vitamin C, vitamin E, selenium, and carotenes, may prevent oxidative problems. Dietary carbohydrate and protein composition as well as timing and frequency of meals have an influence on the effectiveness of levodopa. Levodopa should be taken with a high-carbohydrate meal, and protein consumption should be delayed to maximize the medication’s effect.

There are also foods which are natural sources of levodopa, such as the fava bean. 100 g of fava bean pods contain 250 mg of levodopa, the equivalent of one standard dose.

Nursing care:

The nurse’s role in the treatment of Parkinson’s disease is mainly that of an educator. There are several areas in which Parkinson’s disease patients can be expected to have problems, either from the disease process itself, or from the medications used to control their symptoms:

  • Safety is an important issue for the patient with Parkinson’s disease. The motor difficulties accompanying the disease can set the patient up for falls, burns or other accidents. Falls are the sixth largest cause of death in the elderly population. Patients with Parkinson’s disease have a large number of additional risk factors, such as abnormal postural control mechanisms, orthostatic hypotension, cognitive decline, involuntary movements, and decreased range of motion. In addition, they have the risk factors associated with immobility, such as muscle weakness and decreased bone density. More than half of all Parkinson’s disease patients can be expected to have between one and five falls in a three-month period. The number of falls correlates with the duration of the disease and the severity of the symptoms. 80 percent of patients who experience episodes of freezing (inability to move one’s feet during ambulation) report falls. Walking difficulties, involuntary movements and postural problems are also closely linked to falling, as are postural hypotension, postural lean to one side, use of a cane or walker, requiring assistance with activities of daily living, having given up usual activities, and the daily use of alcohol. Living alone does not appear to increase the risk of falling, nor do use of stairs or type of residence. The peak time for falls appears to be two hours after medications and meals, possibly due to the increased activity at that time. Activities associated with falling are walking, turning, standing, and rising. Many patients may not be aware of the increased risk of falls. It is the nurse’s responsibility to educate patients and caregivers about the risk of falls, and to make them aware of situations when falls are more likely. Use of alcohol should be discouraged, since it raises the risk of falling. Padding knees and elbows may help to prevent injuries while maintaining mobility despite deteriorating motor function.

Burns are also a safety risk for the Parkinson’s disease patient. Carrying hot liquids may present a challenge, due to tremor, involuntary movements and weakness. The nurse should educate patient and caregiver about methods of preventing scald injuries.

  • Sexual dysfunction is also a problem in Parkinson’s disease, and may include impotence, decreased libido, and genital pain. The nurse should address this area since patients may hesitate to bring the topic up on their own.
  • Caregiver role strain is an area that needs to be addressed as well. The caregiver should have access to respite care and be told that it is all right to take a break and have some time for themselves. Counseling and community resource referrals should be initiated as needed.

Patients should be educated about their disease state and their treatments as well as all treatment options available. This should be done in several sessions to allow time for the patient to absorb the information. When the patient has the information available, they gain a sense of control, which is especially important in such a life-altering disease as Parkinson’s.